Re: [Cameramakers] Polaroid 545 or 545i
As was suggested in an earlier posting, there is no reason to use the Polaroid holder for normal film. There is a standard type of holder which you should be able to obtain in any shop knowing anything about large format photography. You should have several of these because each holds only two films until you can get back to a darkroom to remove the exposed film and replace it with unexposed film. I do not even know how you would prevent premature exposure with normal sheet film because the Polaroid holders I know have no dark slide; the latter is part of the film. They are often available used and can cost much less when used, but be careful to check for good condition (especially the light seals and traps.) You may want to consider 9x12 cm holders, which externally have the same dimensions as 4x5. Depending on traditions in your country, you may find one or the other more easily available, though in many places you can buy either one (though you may find a wider choice of emulsions in one or the other.) You can more or less mix them because they both fit the same camera; you just want to be composing according to the film you plan to insert at the time of exposure! Bob At 17:10 15.03.03 +0200, you wrote: I'm asking because I do not know witch one film holder to buy, but someone offer me a Polaroid one. I do not want to use instant film and I'm asking if I can use this Polaroid holder with a normal negative sheet film. I saw in the Kodak ReadyLoad WEB page that the Polaroid 545i can use the Kodak ReadyLoad sheet film but I readed bad reports about the Kodak system. Andy - Original Message - From: John Cremati [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, March 15, 2003 4:33 PM Subject: Re: [Cameramakers] Polaroid 545 or 545i Why would you? Polaroid film holders are used for Polaroid film..(you would wear it out prematurely using everything and anything.) Standard film holders are generally used for film or paper negatives.. - Original Message - From: Andrey Donchev [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, March 15, 2003 9:19 AM Subject: [Cameramakers] Polaroid 545 or 545i Hi, I'm new in large format photography and camera making. Actually now I'm starting to build my first 4x5 folding camera. My question is: Can I use a normal 4x5 sheet film with the Polaroid 545 or 545i film holders? Thank you in advance! Andrey Donchev ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers _ This message scanned for viruses by CoreComm ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Polaroid 545 or 545i
Fidelity or Lisco should be fine. If you can easily enough pay, you might look at ebay, though I don't follow this item and can offer no assurance you will find any of those film holders. My feeling is that with patience you have an excellent chance. There are also stores selling used items and some offer Internet listings. You might try Teamwork(www.teamworkphoto.com/) or Mr. Cad (www.mrcad.co.uk/ ), both in London. I have never dealt with either by mail and do not follow their Internet offerings except very infrequently so it is best for you to follow what they have for awhile, until what you want appears. I believe I have seen used film holders in the Teamwork store, not cheap but well below the price of new ones. I feel confident you can find other suppliers in other countries. Bob At 17:59 15.03.03 +0200, you wrote: I'm from Bulgaria, and the large format Photography is not quite popular here. I must purchase even the sheet film from Internet. So I'm just searching for the best (easiest to manage) decision. Something like Fidelity or Lisko film holders, Kodak ReadyLoad (bad), Fuji QuickLoad or ? Can you give me an advice what to choose! Andy - Original Message - From: Robert Mueller [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, March 15, 2003 4:29 PM Subject: Re: [Cameramakers] Polaroid 545 or 545i As was suggested in an earlier posting, there is no reason to use the Polaroid holder for normal film. There is a standard type of holder which you should be able to obtain in any shop knowing anything about large format photography. You should have several of these because each holds only two films until you can get back to a darkroom to remove the exposed film and replace it with unexposed film. I do not even know how you would prevent premature exposure with normal sheet film because the Polaroid holders I know have no dark slide; the latter is part of the film. They are often available used and can cost much less when used, but be careful to check for good condition (especially the light seals and traps.) You may want to consider 9x12 cm holders, which externally have the same dimensions as 4x5. Depending on traditions in your country, you may find one or the other more easily available, though in many places you can buy either one (though you may find a wider choice of emulsions in one or the other.) You can more or less mix them because they both fit the same camera; you just want to be composing according to the film you plan to insert at the time of exposure! Bob At 17:10 15.03.03 +0200, you wrote: I'm asking because I do not know witch one film holder to buy, but someone offer me a Polaroid one. I do not want to use instant film and I'm asking if I can use this Polaroid holder with a normal negative sheet film. I saw in the Kodak ReadyLoad WEB page that the Polaroid 545i can use the Kodak ReadyLoad sheet film but I readed bad reports about the Kodak system. Andy - Original Message - From: John Cremati [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, March 15, 2003 4:33 PM Subject: Re: [Cameramakers] Polaroid 545 or 545i Why would you? Polaroid film holders are used for Polaroid film..(you would wear it out prematurely using everything and anything.) Standard film holders are generally used for film or paper negatives.. - Original Message - From: Andrey Donchev [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, March 15, 2003 9:19 AM Subject: [Cameramakers] Polaroid 545 or 545i Hi, I'm new in large format photography and camera making. Actually now I'm starting to build my first 4x5 folding camera. My question is: Can I use a normal 4x5 sheet film with the Polaroid 545 or 545i film holders? Thank you in advance! Andrey Donchev ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers _ This message scanned for viruses by CoreComm ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Popular Mechanics Files
Unlike patents, copyrights have very long lifetimes, though I hope an expert will define the rules better. In the case of patents in the USA, I believe the life is 17 years plus the possibility of a renewal for the same length of time. I believe the duration is country-dependent. I don't know about Mr. Love, but when we publish we give up the copyright to the publisher. It is possible Mr. Love did the same, but who knows! Bob At 08:34 12.03.03 -0500, you wrote: Sorry that the plan is so useless also was not aware that 60 years was not enough time and knowing that Mr. Love was deceased thought all was in order. In keeping with this warning of impending trouble the file is no longer available. Sorry if any of those 60 or so who downloaded it are going to be sued by Mr. Soloff or Mr. Hearst. Regrets, Jim - Original Message - From: Marv Soloff [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Wednesday, March 12, 2003 6:22 AM Subject: [Cameramakers] Popular Mechanics Files Not to rain on anyone's parade, but it is my understanding that the material posted on Cameramaker - the E. M. Love article from Popular Mechanics magazine for October 1942, is copyright by Hearst Publications - which still owns and operates Popular Mechanics magazine. If I am correct, Jim Ketcheson who posted the article is in violation of that copyright and so is anyone who downloads it. (As an aside, the article is interesting but archaic - there are better view camera construction articles and copyright free to boot) Regards, Marv ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] 4 x 5 View Camera
To all: Perhaps my email program is more generous than what you have, but for every message which arrives from this group I have quite a lot of data. I reproduce a sample below. You will notice that I have the email address of the person submitting the message, in this case that of Jim himself, as he made us this very nice offer. In fact, I suspect, each participant in this group has the same data but that somehow the program you are using is setup to not display much of the information. However, the beauty of having all of it is that I can send a message directly to Jim rather than over the group. Only Jim need read it (by now each of you has about 10 requests for the pdf file.) Another advantage, Jim must only hit the reply button on his screen and he can get back to you, perhaps with the pdf file as an attachment. I suggest that we can avoid a public display of communications between two persons in this way and use the group postings simply as a way of publishing generally interesting information. Incidentally, I was pleased to see offers for posting the pdf where all can download it. I have longed for such a site attached to this group but having a place for an occasional item is already a valuable help. This is a case where the message was probably basically aimed at a single person but where is DOES have content of general interest. (I was thinking of the need for a place to post something this morning and lacking a server myself, I might be asking about borrowing such capability in the future.) Sincerely yours, Bob # Jim's original message follows, as I see it on my screen. His address appears on the second line. # Date: Mon, 10 Mar 2003 19:19:20 -0500 From: Jim [EMAIL PROTECTED] (Jim's email address) Subject: [Cameramakers] 4 x 5 View Camera Sender: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Errors-to: [EMAIL PROTECTED] Reply-to: [EMAIL PROTECTED] Message-id: [EMAIL PROTECTED] MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Mailer: Microsoft Outlook Express 6.00.2800.1106 Content-type: text/plain; charset=Windows-1252 Content-transfer-encoding: 7BIT X-Priority: 3 X-MSMail-priority: Normal Precedence: bulk X-BeenThere: [EMAIL PROTECTED] X-Mailman-Version: 2.0.1 List-Post: mailto:[EMAIL PROTECTED] List-Subscribe: http://rmp.opusis.com/mailman/listinfo/cameramakers, mailto:[EMAIL PROTECTED] List-Unsubscribe: http://rmp.opusis.com/mailman/listinfo/cameramakers, mailto:[EMAIL PROTECTED] List-Archive: http://rmp.opusis.com/pipermail/cameramakers/ List-Help: mailto:[EMAIL PROTECTED] List-Id: E-mail discussion about homemade cameras cameramakers.rmp.opusis.com Status: I have a PDF file covering the making of a 4 x 5 view camera from Popular Mechanics Magazine for October 1942. The file is 1,049 Kb in size. If anyone wishes this file please let me know. Jim Ketcheson Belleville, Canada ## At 10:02 11.03.03 -0500, you wrote: To Jonathan King - unable to send as you did not provide your email address. Jim - Original Message - From: Jonathan King To: [EMAIL PROTECTED] Sent: Tuesday, March 11, 2003 6:40 AM Subject: Re: [Cameramakers] 4 x 5 View Camera On Mon, 10 Mar 2003 19:19:20 -0500, Jim wrote: I have a PDF file covering the making of a 4 x 5 view camera from Popular Mechanics Magazine for October 1942. The file is 1,049 Kb in size. If anyone wishes this file please let me know. Please add me to the list too. Thanks, Jon King ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Packard shutter with synch
I would just illuminate a piece of paper with the flash and then look through the shutter at that paper while the flash (shutter) is fired. You should see the full opening for a fleeting instant. Bob At 23:12 19.02.03 -0500, you wrote: I tested my Packard shutter with the 2 wires by attaching them to an Argus flash unit with a flashbulb, and then to a small electronic flash unit, and it fires both of them. How can I tell if the synchronization is good? I'm building a camera with the Packard and will provide for attaching flash if the shutter actually is in synch. Marty Magid ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] re: aerial cameras
I have seen photos of reels for long lengths of film in which it was wound onto a sort of drum, except the drum was just a series of thick wires arranged parallel to the axle and forming an open cylinder. The film was just wound onto this as a helix (like the thread of a screw). You will have to support these wires so they do not relieve the tension on earlier turns as later ones are put on. You can just put this in a tank, or more likely, in a tray. I have seen an occasional 35 mm camera taking long rolls yet not hopelessly big, like one probably intended for ID photos. Sadly, that source dried up, but maybe you can find something similar. Bob Joe Herdler wrote: Hi all I appreciate all of the ideals about aerial photography. I was in a real hurry when I posted my question about aerial photography in model aircraft. I am presently building a full scale Sopwith Pup, from copies of the original drawings. (I have about 200 hours in this so far, and another 150 to 200 to go, not including prepping an engine, which someone else will do.) I want to experiment with the RC set up, then transfer to the 'Pup. I ultimately want to start an aerial imaging business...even if the business doesn't fly, (pardon the pun), I am nosey, and want to be able to make excellent images from the air. I have found a strange 16 mm camera on e-bay that will do single frame shots on bulk film...I bought it and am waiting on it to arrive, and I am sure that like everything that I have bought on e-bay that is listed in near mint condition, I will have to spend a lot more money on it to just to get it into working condition. Ultimately, I would like to find either a commercial aerial camera that can be fixed in the fuselage of my plane (35 mm), or find someone who can build one. I don't have the machining skills necessary to do that myself. Another question if I may...does any one on the list have any knowledge of processing bulk film I can't see myself trying to wind 100 feet of film on a tank reel. Thank You for entertaining my questions!!! Joe - Original Message - From: Robert Monaghan [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Sunday, February 09, 2003 3:21 PM Subject: [Cameramakers] re: aerial cameras Actually, I'd suggest you reconsider and look in the latest issue of NUTS and VOLTS magazine, also past issues of QST magazine (the ham radio magazine) which deal with model airplane mounted chip color video cameras and small 450mhz and 1.2 gigahertz tv transmitters. Chip camera with 75 milliwatt TV transmitter weigh a few ounces. With good lighting in daytime, you get some impressive photos of the neighborhood ;-) ;-) see also balloon borne TV http://www.qsl.net/w5sjz/balloonpj.htm - they have a really impressive set of photos of a balloon at 90,000+ feet, you can see clouds waaay below, with the black curved edge of atmosphere out to the sides, very impressive. They also caught the weather balloon when it exploded, like glass since it was so frozen at high altitude, dropping setup to parachute to earth (GPS signal for quick recovery). Our campus radio club is setting up an amateur television station next weekend (receiver), and I hope to get student club $$ this month for a transmitter (60 mile range). One exploit planned is a tethered balloon on campus with a rotating mirror at 45 degrees to image the campus ;-) an alternative, if you have to use film, is a relatively light 35mm point and shoot with electronic switch trigger and motorized drive; you can use a remote control or setup a timer (555 chip from radio shack) to pulse it and take a photo every ten seconds or so. See kite photography and similar links at http://medfmt.8k.com/mf/links.html for tips, mf/aerial.html Hope this helps bobm * Robert Monaghan POB752182 So. Methodist Univ., Dallas Tx 75275 * * Third Party 35mm Lenses: http://medfmt.8k.com/third/index.html * * Medium Format Cameras: http://medfmt.8k.com/mf/index.html * ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] 16mm still camera
Thanks for the correction. It has been a long time since I saw one and I just mixed up the names of the makers. Sorry. If my memory is correct on one other point, I believe the Kiev 16 is very similar to the Minolta 16, enough so that I could put a Kiev cassette into a Minolta with a slight modification. Bob At 00:31 05.02.03 +0300, you wrote: Robert Mueller wrote: ... There were various cameras taking short lengths of 16 mm film, from Minolta, but I believe also Pentax and Lomo. Not LOMO but Kiev. Kiev 30 or Kiev-Vega models might be what you had in mind. Those came from Arsenal factory in Kiev -- not any more. LOMO factory is mostly known abroad for the LOMO-Compact Minox clone associated with the lomography. It takes 35mm film (135). Regards Mikhail ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] 16mm still camera
I expect you will have trouble if you want a camera taking a full roll of 16 mm film. It will probably be pretty big=heavy. However, if you can carry one and find one with single frame capability, you can very many photos on a single flight. (Not every movie camera offers single frame ability.) There were various cameras taking short lengths of 16 mm film, from Minolta, but I believe also Pentax and Lomo. The Minolta models I know lack interchangeable lenses but I think there is a Pentax offering this feature. I suspect the LOMO is still available as a new camera (might be old stock; I have not seen one for sale for some time.) The Minolta 16 and Lomo are fairly compact and light. You can pick them up for relatively little money on ebay BUTTT, be sure you get a few cassettes with it! That is probably easier with the Lomo. I have tried obtaining cassettes for the Minolta and they are rather rare, though there was a company selling them, loaded, at something like $25 each, with good films in the load. You might want to look at 35 mm cameras if you do not need too many photos on a flight. Some compact ones are not hopelessly bigger than the 16 mm models. You would have to find something with auto film advance. Interchangeable lenses are probably out but zoom is possible if you are willing to risk a more expensive type. Being plastic they are usually not too heavy. You might also think about an inexpensive digital model. For about $100 you can get 1.3 Mpixel, no power wasted on winding, and with a big memory card you can store a few hundred shots. These have autoexposure which you might not find in an older 16 mm camera. 16 mm was already a semi-professional size long ago. A semi-professional camera will probably be large and heavy and expensive. The photos will be excellent if you can carry the thing and don't mind risking it. Back when 16 mm was still a common amateur size autoexposure was likely to be a little rare. Of course, you don't need it on days with stable lighting. bob At 22:34 02.02.03 -0600, you wrote: Hi This is my first post to this list. I am very interested in either building or buying a camera that will use bulk 16 mm movie film for aerial photography in RC planes. No SLR or any thing fancy, just a basic camera with changeable lenses, set to infinite focus. Any ideals or info would be greatly appreciated. Thank you in advance. Joe [EMAIL PROTECTED]
Re: [Cameramakers] Light source for enlarging onto platinum-paladium and Kodak Azo papers
There is a second reason for wanting a shutter, namely, certain (many) kinds of discharge lamps greatly dislike being turned on and off very often. The lifetime can be drastically shortened. Needing a ballast and a lot of UV strongly suggest these are discharge lamps. It is worth checking the manufacturer's specs on this detail. Because the bulbs are fairly expensive this factor may influence your choice of lamp type, or at least your mode of operation (perhaps you will turn it on for the planned working period and depend solely on a shutter for control.) Bob PS Don't forget the power requirements if this is for home use. You can rarely take 10 kW out of the basement socket (that is enough power for a sauna and more than enough for the kitchen oven). In an industrial environment this will be less of a problem. At 16:37 01.02.03 -0800, you wrote: Thanks John, I appreciate all of the information on the El Nikor transmission capabilities. I will look forward to the layout of the bulbs in your lampsource. I have located a source on the east coast that makes lamps for UV curing and they have the capability to target a given UV range. They indicate a wattage output of 300 per inch of arc length. So a couple of 6 inch lamps should kick the output to something on the order of 3600 watts. They indicate that they will sell these in less then ten lots and they appear to be on the order of a hundred and change for each lamp. I have also located a ballast source that produces a variable ballast that achieves it's variance through varying the frequency of the voltage. The problem is that they indicate 450 watts as the upper limits of their ballast. I may need to go with a conventional ballast(s) as that problem is still not resolved. I am presently using a Saunders 4550 XLG as the enlarger for my 4X5 negatives and that has a 250 watt lamp. So I would think that the wattage that I am looking at should work for Azo at least. I do have an older Omega D2 that I will probably work with initially on this project. The problem that still exists so far as I am looking at it is that these lamps need a stabilization period to achieve consistant light output after strike. So it would seem that a shutter of some type may need to be incorporated in the light path. I think that possibly replacing the pneumatic actuator on a Packard shutter with an electrical solonoid would work for the shutter. The problem is that an potential vibration of the solonoid strike would need to be dampened. If you come up with other considerations that I am not addressing, please communicate those to me. Again, I will appreciate your light source configuration and reflector arrangement if one exists. Thanks again for your input. Regards, Donald Miller John Cremati [EMAIL PROTECTED] wrote: Donald, Here are some of the treads on the discussion of UV transmission thru El- Nikor glass from the Alternative Photo list.. I hope this will help... Please keep me informed of your progress as I am extremely interested. I kind of dropped the ball after getting this information and have still not hooked up my enlarger.. I will measure the spacing on the pulsed xenon bulbs.. I believe there were four in parrell close to a ground glass for diffusing and then there were two longer more powerful tubes .. crossing behind the 4 that were perpendicular forming a checker pattern. ... I do not think that these bulbs were on for any length of time as they were intended to expose ortho film which I believe has a ASA rating of about 5 or so and at 10,500 watts , that would not take long.. . I think the infrared will be a problem on long exposures... I was considering rigging some sort of Air conditioning system for the film chamber as I do not know if the fan will be enough... The enlarger will handle up to 11x14 negatives and has a 30x40 vacuumed frame for the enlargements .. .It is 10 feet tall and weighs 3000 pounds..(.This is probably the main reason that I have not hooked it up yet..) John Cremati .. Scientific graphics supply catalog that all Nikon El Nikor Enlarging Lenses were made of a special optical glass to allow passing of UV waves between 350 and 450 nm.. I have also read of Sun enlargers utilizing sunlight as the light source thru a lens to enlarge during the turn of the century in the book Keepers of Light ... Bit lefthanded! If you compare BK7 and UBK7 at 350nm, the difference ... Here's some interesting information I picked up from a Nikon Catalog about their enlarging lenses: EL-Nikkor enlarging lenses are corrected for chromatic aberration beyond the visible spectrum into near ultraviolet wavelengths -- wavelengths to which photographic papers are particularly sensitive. Through the use of special optical glass and matching optical coatings, EL-Nikkor lenses are designed for ultraviolet transmission in the 350 to
Re: [Cameramakers] Light source for enlarging onto platinum-paladium and Kodak Azo papers
Certainly if the material has appreciable sensitivity in the visible range the user would be advised to put as much light as possible in this range, where the optics are properly corrected. Bob At 01:04 02.02.03 +, you wrote: Aren't there other issues concerning the image quality that haven't been addressed? I can think of: (1) The enlarging lens must not only have the ability to transmit the UV radiations which are to expose the paper, it must have the ability to form a high quality, well-focused image in the wavelength range which is relevant. (2) If the photosensitive paper has any appreciable sensitivity to wavelengths outside the UV range, for example to wavelengths in the visible range, then the enlarging lens must bring these other wavelengths to the same focus as the UV or else they must be excluded from the illumination. RKS _ Help STOP SPAM with the new MSN 8 and get 2 months FREE* http://join.msn.com/?page=features/junkmail ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] bullet photog, mega-lens
I would much appreciate information on how I can contact this fellow regarding a lens making problem. May I have an email address, telephone number, or even his postal address? He might be just the person to amke up something for us! THANKS in advance. My email address for the information is [EMAIL PROTECTED] Bob Never give up is my second topic - I contacted a second buyer of one of those monochromatic 40 pound lenses - and he has lens software and can grind lenses up to 12 diameter. All I was armed with were ideas. He's had his apart already - it has 4 cemented pairs that are air-spaced. We're scheming about some sort of change. He claims it has no internal reflection, but I suspect one needs to look under the right conditions and not just eye-ball for reflections...no Bokeh? Murray Murray ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Light source for enlarging onto platinum-paladium and Kodak Azo papers
It depends how far into the UV you go. Many glasses transmit a fair amount of near UV. Which wavelength is needed for this process? Bob At 07:15 01.02.03 -0800, you wrote: If I remember right, UV doesn't like to pass through GLASS. Gene - Original Message - From: DONALD MILLER To: [EMAIL PROTECTED] Sent: Saturday, February 01, 2003 6:39 AM Subject: [Cameramakers] Light source for enlarging onto platinum-paladium and Kodak Azo papers I am working on development of a light source to allow enlarging of images onto pt-pd and Azo papers. These papers need a light source in the upper UV band (350-475 nm). The other consideration are that these emulsions are markedly slower then conventional enlarging papers. I have two immediate concerns those being: 1.UV is largely invisible and this presents the problem of focusing the image on the easel. I could incorporate a conventional focusing light. If I do so will I experience focus shift when I switch to the UV lighting? Furthermore, will UV reflect in the same manner as visible light? I ask this because the light source will be diffusion to eliminate the cost of building condensors or buying a condensor enlarger since I already have three diffusion enlargers. 2. Will UV transmit through a conventional multicoated enlarger lens? I have an el-nikor 150 as my primary lens. I also have an older Schneider companon 135 mm which I think is uncoated. My Rodenstock medium format lenses are all coated. Any information or insight that you may provide will be greatly appreciated.
Re: [Cameramakers] Light source for enlarging onto platinum-paladium and Kodak Azo papers
Further comment, following my previous one! The below listed wavelengths do pass through many glasses. Focusing will be somewhat of a problem, though you might be able to something similar to what is do for IR photography; find the right shift of focus, do it in the visible and then make the shift before exposing. There is another way. You can find fluorescent screens emitting in the visible when bombarded in the UV. Such materials are actually rather common. Many kinds of paper do it because they are deliberately dyed to cause them to do so. It gives the paper a whiter appearance. Better might be some materials which are overbright because they are printed or painted with DAY-GLO colors. (However you spell that!) You would want to suppress the normal part of the light you are viewing so you can see the consequences of the UV light. This could be done with a filter, probably in the light source or between the lens and the paper. Bob At 06:39 01.02.03 -0800, you wrote: I am working on development of a light source to allow enlarging of images onto pt-pd and Azo papers. These papers need a light source in the upper UV band (350-475 nm). The other consideration are that these emulsions are markedly slower then conventional enlarging papers. I have two immediate concerns those being: 1.UV is largely invisible and this presents the problem of focusing the image on the easel. I could incorporate a conventional focusing light. If I do so will I experience focus shift when I switch to the UV lighting? Furthermore, will UV reflect in the same manner as visible light? I ask this because the light source will be diffusion to eliminate the cost of building condensors or buying a condensor enlarger since I already have three diffusion enlargers. 2. Will UV transmit through a conventional multicoated enlarger lens? I have an el-nikor 150 as my primary lens. I also have an older Schneider companon 135 mm which I think is uncoated. My Rodenstock medium format lenses are all coated. Any information or insight that you may provide will be greatly appreciated. ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Speaking of fluorescent cold light heads , help with luminance question also
You need conversion factors from watts to lumens. Those depend on human eyes which have a great variation of sensitivity with wavelength if you measure incident light in watts. You can find plots or tables of this, but at the most sensitive wavelength it is somewhat above 600 lumens per watt (one reason some of those yellow colored street light achieve such intense illumination for so little electrical power input.) There are a few photodiodes made with built in filters to render a sensitivity versus wavelength resembling that of the eye. (The glass on the ones I have is greenish in tint.) There also is a Wratten gelatin filter (I believe #106, but check a data book) which converts normal diode sensitivities in the same way as that glass. It is probably cheaper to buy a diode already equipped with a filter! I don't have the data at hand, but I can imagine such a diode having specs given in microampere per lumen. I doubt diodes give a single value of mV per microwatt. Current into a short circuit will be linear with incident power (or lumens), but not voltage. The latter normally has a log variation of voltage with power and with a non-trivial temperature dependence. Bob At 20:52 17.01.03 -0500, you wrote: Getting uniform lighting over a large area with a homebrew fluorescent source may take some effort...I have an idea to follow some day. I am working on my homebrew spotmeter idea. Silicon photodiodes have typical sensitivity rating in mV per uW/cm^2. I see that as meaning voltage as a function of optical power density. The number of dimensional units involving illumination and luminance and all the physical variations and unit systems are confusing. I've charted luminances vs. EV numbers, shutter speeds and apertures. Now I need to relate luminance and the above-described photodiode sensitivity. I have the sensor area for a couple different size sensors if that is needed. I'm having a hard time figuring out the dimensional analysis (what physical parameters are missing or needed). Any help appreciated. Murray --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.391 / Virus Database: 222 - Release Date: 9/19/02 ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Helical Focus Mount
This is possibly a help but I admit problems! I just returned from London and Jessops Classic was offering old (low grade) 35 mm lenses for one pound each. Your cost would be almost all postage. Some member of this group might buy a bunch and ship them to anyone needing one. ( I didn't buy many because of overweight baggage problems.) Of course, the mounts would be most useful for smaller lenses. Sometimes you can pick up a cheap lens at a flea market. Bob At 17:47 14.01.03 -0500, you wrote: Hi Folks, Does anyone know a source of cheap helical focus mounts? Can I make one out of PVC pipe fittings or something similar? Thanks, Dai. - Daisuke Nakabayashi [EMAIL PROTECTED] http://www.justdai.com - ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] opaque projectors or enlargers
Why don't you look at an over-the-shoulder (Overhead) projector. Then make photocopies as transparencies. The image will be much brighter. Opaque projectors are extremely wasteful of light and the overhead kind are far better. Today photocopies are fairly cheap, even in color. Meanwhile, I expect overhead projectors to become cheap because speakers are turning to PowerPoint and beamers. I can imagine many overhead projectors on tomorrow's scrap heaps. I recently took apart an opaque projector but it could only handle 4x5 (It was already a pretty big thing and I could not imagine anybody paying the shipping, let alone enough for the item to justify my effort in arranging packing and transportation. I got tired of storing it, yet the optics were good, once taken out of that big housing. I dread to imagine an 8x10.) And the image was visible, but weak, although the lamp ate over 500 watts. Bob At 10:33 01.01.03 -0500, you wrote: Sir; I am interested in knowing more about buying a used opaque projector. I am a School Art teacher and artist, I wish to buy an inexpensive projector that will accept a 8x10 image and project it on a wall to the size of 5' x 6'. without much distortion. Would Government Surplus be good? What do you have for sale? Please advise. I live in the south Fla area. thanks Joe
Re: [Cameramakers] Spotmeter
You are right; a home-made meter could be as good, and with little extra effort, better than a commercial model. It would not even be too hard if you do not insist on too many bells and whistles. I finally bought a commercial one and modified it to live without mercury batteries and to overcome some troubles with loss of sensitivity (wrong readings!) over the years so I gave up on actually making a meter but I see nothing difficult if you know a little optics and electronics. The problem mentioned below, freezing the reading is also not serious. There are commercial digital voltmeters which have a freeze button, but if you start at the IC level, there are IC DVM chips which include the freeze function (look at the old Intersil stuff or the newer but similar parts from MAXIM). My own plans included Display in the viewfinder, best done with small LED readouts but LCD has some valuable advantages (and backlighted LCD s do it all) (incidentally, you must keep light for / from the display out of the photodiode.) Freeze of reading Diode, not photoresistor sensor, for great linearity Good input amplifier for excellent sensitivity meaning taking pictures in terrible light. Today amplifiers measuring to a couple pA are easy to find, also in low power versions, and getting well below 1 pA is not hard if you know what you are doing (leakage currents are deadly!) Make the amplifier have a log output of the input current. Not only is this convenient for the photographer, it makes obtaining wide dynamic range almost a snap. You do have to include some temperature compensation for the logging transistor(s) but that is adequately described in the appropriate books. Simple optics in the measuring path to avoid unnecessary reflections, and carefully designed baffles for the same reason. I have read this is where some commercial meters loose out to other models. Do any image inversion in only the viewing path. Probably easiest with a penta prism combined with the beamsplitting mirror to form an erect image (but maybe large format folks are happier if the image is inverted!) An old penta prism from a dead camera would be fine, though maybe larger=heavier than ideal. You could consider including the bells and whistles like a microcomputer chip to give a diaphragm setting to match your shutter speed, and all the similar features which eliminate most work. Today this is relatively easy at rather low power consumption (low power means slow speed to some extent, but how much computing speed is needed to calculate a shutter speed/diaphragm pair.) Some modern microcomputer chips are quite cheap and easy to program if you have the correct software. Probably lithium battery, though any kind will suffice if you regulate voltage. I considered trying to guess which types will be available for the remaining duration of my life (somewhat less than another generation) and designing around that. And I wanted a type which is unlikely to leak and then probably in a leaktight housing in the sense that if there were ever a leak it would be unable to reach the optics and electronics. Sensitivity goal; photos by moonlight (perhaps to quarter moon or better) Anyway, all this looked fairly easy in the sense that risk of failure was low and very little development would be required beyond spending enough time to engineer a comfortable housing and a good method of being sure the circle in my viewfinder was very similar to the circle sensed by the diode (That looked the hardest!) Bob At 07:25 20.12.02 -0800, you wrote: It would be very hard to make a homebrewed spot meter as nice as a Pentax, for example, but homebrewed meters in general can be VERY accurate. I made a small series of meters made from cheap handheld digital V-O-M meters which used a photoresistor . I had a chart to convert ohms to shutterspeeds at a couple different apertures and filmspeeds. Kind of clunky, but very accurate, and extremely sensitive. I thought about trying to make a spotmeter but never did. I was stuck on a way to freeze the display so that when I took my eye from the peeper, the display would still show what I was looking at. I now have a nice analog Pentax Spotmeter so I can fiddle with other things. Gene - Original Message - From: John Yeo [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, December 20, 2002 6:56 AM Subject: Re: [Cameramakers] Spotmeter Or, better yet, why not modify a pair of binoculars. Have one side function as a finder and the other as the meter. That way, you wouldn't have to worry about metering through a one way mirror that may affect the reading by polarizing the light. You could put a plane of glass at the location of a virtual image inside the binocular lens assembly (if there is one) with a circle on it to show the area being metered. This is also where you would want to put the display that gives the meter reading. Of course the
Re: [Cameramakers] bellows liner sheen
I am not sure this is possible but you can coat the stuff with thin layer of silicone of the sort used for sealing bathtubs, aquariums and... You can thin it with a considerable amount of mineral spirits (it takes a lot if you want to brush the result). Add enough carbon black (I had success with about 10 % printers ink) to make thin layers quite dense. This will fill the pores and also increase the resistance to some kinds of damage (and could be used to bond the fabric to the next layer). If you now uniformly press this mess onto a suitable sheet of polyethylene or other non-stick material which has the surface appearance you desire, you will copy the surface in the silicone! The real problem is finding a non-stick layer of something having the correct surface. Much polyethylene is too shiny and the end result would be worse than you now have! Still, if you can locate the correct stuff, I am quite sure the process will work. There is a second point of view; I cannot think of any reason to worry about the shiny appearance! Yes, it reflects in a specular way, but if the source makes a broad beam, the specular reflection of that beam will be no less well spread out. The main source of light is what bounces back from the film or film holder. Certainly the film scatters light well and probably the black film holder is not too bad either. It can easily be that a flat black surface reflects considerably more total light than your shiny one. It is hard to produce truly dead black. Light traps offer the best hope and flocking is one way to reach this goal. I have seen a bellows with partially flocked inner surface. If you are good, maybe you can flöocking to adhere to the silicone (but hurry, before a skin develops!) Bob At 08:39 26.11.02 -0500, you wrote: Hi, I am in the process of building a 24x24 camera bellows and I found this wonderful material called Emphatex. . It is a 2 ply coated breathable nylon material used to make sports gear..It is extremely thin , light and subtle and is almost 100 percent light tight by itself, however it does pass a very little light.. ... With two layers I am sure it will be completely opaque.. The question or concern I have is that the material has a slight or dull sheen to it and I was wondering how critical do you think it is to have a liner in the bellows that is dead flat black? If it is critical does anyone have any suggestions to dull the sheen.. Also is there any recommendations for liners that are dead flat black.. Thanks, John Cremati
[Cameramakers] Protection of a camera against leather corrosion
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[Cameramakers] Protection of a Camera against Leather Corrosion
Sorry; I think I just sent an empty posting! Frequently when repairing medium format and 35 mm cameras one must lift the leather to get at screws. Typically there is corrosion under the leather and I assume it is either chemicals in an animal skin or chemicals used to process the skin to leather which cause the corrosion. The question, is there anything to do to prevent such corrosion in the future? The obvious possibilities are treatments of the leather (maybe to neutralize acids, such as tannic acid or others (chromic acid?)) or an impermeable barrier which blocks the troublemakers from reaching the metal. Of course, the leather must not be harmed in either the short term or the long term. Can one wash out whatever the source of trouble might be and then soften and protect the leather with some kind of oil which does not prevent adequate gluing to the camera? Bob ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Oil \ lubricant
Dear Peter, When I last checked the USPS prices they were a bit over $18.00 for the first pound on a package with air even a little cheaper than surface. The small packet rate is lower and for a bit of oil maybe first class is the best choice. Actually, you probably have little motivation to go for the parcel post rate because you probably can get by without insurance. Thus you can keep the shipping below the pain threshold! At least if you do not loose control (for example, if they routinely used insured methods and you don't ask, well, its $18.00+) There is a rate calculator for USPS on the Internet. I have printed data, and they don't always agree, and what happens at the post office is again different, but you do get some orientation! Bob At 01:50 10.10.02 +0100, you wrote: On Wed, 09 Oct 2002 13:32:37 +0200, you wrote: I discovered you wouild be buying in the USA; I suggest that you try a local source. There are two good reasons, or more! 1) You avoid the USPS (United States Postal Service)/Consignia (Former Royal Mail) customs scandal. Besides the postage for overseas shipment you can easily be hit with an additional (semi-secret) charge of about 20 Euro for clearing the package through customs. This comes into play for goods value exceeding about 45 Euro (and the value can be assessed as the sum of goods plus postage, as is the case here, in Germany. I don't know about the UK way of calculating.) Consignia then gets the package to you using local (to you) contractors who are sometimes terrible, though in the UK they may handle the delivery themselves. In fact, the arrangement seems to cover much of the continent with Consignia as the prime contractor with whom the USPS deals. In addition, USPS is slow for air mail (often, though not always) and too slow to believe for surface mail (2 months is not uncommon and less than a month is rare.) And they do not give you bargain rates for the poor service! 2) Payment is easier inside the UK (for you!) Two companies I know are Shesto and Walsh. Walsh was in London (near Farringdon Station, the old clockmaking district on Clerkenwell) but at least part of their operations have been moved. I believe both companies have WWW sites. You might also look for Cousins. Bob Hi Bob, My understanding is that you only pay duty on items costing more than £19.00. I've bought things from the US under this amount without problems in the past. The oil I've just ordered only comes to a few US dollars. Airmail postage can't be too much as the say they charge only what it costs them. The company takes online orders with a Credit Card. Peter Peter Jones wrote: On Wed, 09 Oct 2002 03:59:22 +0100, you wrote: Hi. I have a Canon AE1 which has developed the famous Canon Squeak associated with the mirror return. I have the information to fix the problem, but was wondering if any one can suggest a source for the very light oil required ? I should add that I live in London in the UK. Thanks, Peter -- -- To answer my own question - I just found this site which seems to have just the thing: http://shorinternational.com/WatchOilGrease.htm Peter Jones[EMAIL PROTECTED] London NW6 ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers -- -- Peter Jones[EMAIL PROTECTED] London NW6 ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers -- -- Peter Jones[EMAIL PROTECTED] London NW6 ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Oil \ lubricant
Dear Peter, You may not detect it but I am an American who has been in Europe for a couple decades now. I have little respect for the USPS. There was a time when it was a proud and effective organisation as seen by the user; today it is an imitation of a private company which combines the worst features of a government organisation and a commercial operation. I sometimes say that if we offered it to a third world country the insult would be so l large diplomatic relations would be broken off. I am sad to say I am not all that impressed by the British Post office these days, though I have heard it looks very good when serving inside the UK. From outside it I am afraid it does not look so hot. I once spent some time in Japan and thought highly of their post office and Germany's is normally good, but what is interesting is service between these two countries. They may be far apart but mail travels in about four days from where it is deposited to the door of the receiver. When I have mailed a post card from London to friends back here, 10 days later after I arrived home the post card was still not here. This has improved in recent years but is no model, especially when you consider it takes only 10 hours to drive, including the ferry crossing. This over 10 day trip was called Air Mail! Last year I spent a fair amount of time trying to learn why it took two months for the BPO to return a letter to my bank which had mover across the street. The address was no longer valid so it was sent back, but very slowly. Each phone call to Royal Mail customer service brought a promise of a response after the reason was checked, and each response was none at all. On the next call I learned the file was just closed again and the promise scrapped. The German post office is more efficient but it cheats! The EU has hit them over the head for refusing to eliminate a subsidy of package post by excessive prices on letter post. Finally enough threats did stop the cheating but only because there is an activist in Brussels. Good luck with your order. (One thing I do from time to time is buy insurance. It gives a handle on tracking a package. There is now a service allowing you to trace the travels of your package for a small fee. The trouble is that I think these are only available for the high priced class of postage and I doubt whether it is worth the bother or cost for a bottle of oil. Also, I can not remember ever loosing a package. It just takes forever from time to time and damage is too frequent for my taste, but most things do arrive.) Bob At 20:33 10.10.02 +0100, you wrote: On Thu, 10 Oct 2002 11:54:39 +0200, you wrote: Dear Peter, When I last checked the USPS prices they were a bit over $18.00 for the first pound on a package with air even a little cheaper than surface. The small packet rate is lower and for a bit of oil maybe first class is the best choice. Actually, you probably have little motivation to go for the parcel post rate because you probably can get by without insurance. Thus you can keep the shipping below the pain threshold! At least if you do not loose control (for example, if they routinely used insured methods and you don't ask, well, its $18.00+) There is a rate calculator for USPS on the Internet. I have printed data, and they don't always agree, and what happens at the post office is again different, but you do get some orientation! Bob Hi Bob, USPS pricing structure does seem rather odd. I tend to find myself having to explain to some Americans which service to ask for or use. It makes the UK postal system look a model of common sense - surprising really. Peter At 01:50 10.10.02 +0100, you wrote: On Wed, 09 Oct 2002 13:32:37 +0200, you wrote: I discovered you wouild be buying in the USA; I suggest that you try a local source. There are two good reasons, or more! 1) You avoid the USPS (United States Postal Service)/Consignia (Former Royal Mail) customs scandal. Besides the postage for overseas shipment you can easily be hit with an additional (semi-secret) charge of about 20 Euro for clearing the package through customs. This comes into play for goods value exceeding about 45 Euro (and the value can be assessed as the sum of goods plus postage, as is the case here, in Germany. I don't know about the UK way of calculating.) Consignia then gets the package to you using local (to you) contractors who are sometimes terrible, though in the UK they may handle the delivery themselves. In fact, the arrangement seems to cover much of the continent with Consignia as the prime contractor with whom the USPS deals. In addition, USPS is slow for air mail (often, though not always) and too slow to believe for surface mail (2 months is not uncommon and less than a month is rare.) And they do not give you bargain rates for the poor service! 2) Payment is easier
Re: [Cameramakers] Oil \ lubricant
It would be tempting to use just any light oil to treat the AE-1 squeak but normal mineral oils have a troublesome property; they wander, crawling over the surface. This takes the oil away from where you want it and deposits it somewhere you definitely don't want it. Clock and watch oils often contain either animal oils selected for stability against oxidation or synthetic oils, and possibly a mixture.These are better in the above critical properties. Can anybody tell me more about getting rid of the squeak in the AE-1; as soon as I fix my tungsten cable problem I might have to deal with my own squeak? Bob ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Oil \ lubricant
Thanks!! Bob To cure Canon A-series squeal, remove front apron (4 screws), remove top left lens mount screw insert oiler --- deposit one drop of oil where the flywheel contacts the nylon gears. Paraphrased. Better if you can locate Joe's book and take a look at the pictures. Very easy, but incredibly easy to totally screw up the camera if done wrong. Regards, Marv ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Thin Al for dark slides (or whatever you want to do with it!)
While I was in our shop today I recalled the thread on dark slides and began to wonder whether a source of metric material could help anybody. I can probably get this and I am willing to do so if the person desiring it is willing to pay the price of the material and shipping and has the patience to wait for me and the post office! I believe I can get 0.5 mm, 1.0 mm and maybe even 1.5 mm. I cannot ship you a whole sheet intact but I could shear it to a single size plus the left-over odds and ends. To suggest a possibility, I could cut to a little over what you need for your favorite format with a small allowance for finishing the edges. The above thicknesses are rather too thin for the huge format film holders which have been getting much attention lately! The 0.5 and 1.0 mm bracket 1/32 inch (0.02 and 0.04 inch compared to about 0.03125). I do not know the exact postage and would have to look it up after knowing what size you want because weight does go into the amount. However, you should not expect to get by for less than 30 Euro and probably it will be somewhat more. Also, if you are in the USA, you might be able to do better getting material shipped from Canada where such sizes are likely to be common and the postage might be less. Conversely, if all else fails and only one or two persons wants this stuff badly enough, I will try to help. I think the alloy we use mostly is 3% Mg. The material comes protected on one side by a plastic film. It is not polished but more-or-less semi-gloss. Again, I have never bought any so I do not know the price of the raw material either. This alloy can be anodized. The sheets are probably 1 meter x 2 meters, enough for several dark slides. You can estimate shipping weight from the thickness and area 100 cm x 200 cm x 0.1 cm = 2000 cubic cm and at 2.7 grams / ccm, about 5.4 kg. That probably costs something around 35 to 44 Euro (the latter covers up to 12 kilograms) for postage but you might be able to get two sheets shipped at the same price, most interesting if a friend wants some, too. I do not expect to be overwhelmed by requests and I surely hope it doesn't happen, but if somehow I have stuck an unwanted resonance I will have to limit this to the first couple persons who need it. Sorry! Bob ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Ilex Process Paragon
From the photos I cannot judge but the electrical thing on the back of the lenboard is probably a shutter operated by a rotary solenoid, most likely made by LEDEX. Instead of a linear motion the shaft turns with application of an adequate voltage. It might operate something else than a shutter but you should be able to tell that by manually inducing the rotation. I will avoid letting my imagination run wild regarding what it might be when it is NOT a shutter! Bob At 20:23 27.09.02 -0400, you wrote: http://www.uptowngallery.org/ilex1.jpg http://www.uptowngallery.org/ilex2.jpg If anyone can identify what the mechanism did, it would be appreciated. Thanks Murray ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Stepping motors / was making a panoramic camera
Please look at the old floppy drives. The motors are typically almost cubes 40 to 50 mm on a side. (There are exceptions of various kinds so try again if the first one you look at is not suitable.) I have a few nice steppers which are flat disks less than 20 mm thick, if my memory is failing me, but maybe 60 or a bit more in diameter. However, these have lots of steps (400 to 500) and need only two phases to drive them. (I would offer you one except the postage is terrible from here!) Unfortunately, many 500 step motors are 5 phase models; good stuff but not convenient for this application. The steppers in 3.5 inch floppies are tiny but I would not bet on their ability to drive what you have in mind at the speed you want so I would avoid them unless you are quite adventurous! How fast does one of these cameras complete a sweep? Besides steppers, normal motors run at pretty constant speed if the load stays constant. You must just keep the voltage constant. There are some tiny motors with gears in dead CD drives. The voltages are low so battery power is little problem. Bob At 22:49 26.09.02 +0200, you wrote: Thanks Bob and Huw . Well I know a little about electronics, they were part of my studies but it's a bit far away now :o) I got a few step motors but from old printers they are really huge ones and from the scanner that broke up it's a 7.5 degrees I can gear it with all the pulley and belt I collected from various things but well in fact I've got to test different solutions because I do not want a 20 pounds camera (without the battery ) ! :o) ( Well after that I'll have to do a led enlarger for panoramic shots !! ;o) ) Cedric On Wed, 25 Sep 2002 22:51:47 +0100, Huw Finney wrote: Hi, Stepper motors can be geared and it works very well, take a look inside a printer (to be found in your local skip (dumpster)) there is usualy a couple of big steppers and some gears and a very useful toothed belt. There are plenty of stepper driver chips out there. If you get stuck on the electronics I can sketch something for you. Huw (of LED enlarger fame) ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers -- Cedric Malitte, [EMAIL PROTECTED] on 26/09/2002 ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Making a Panoramic Camera
If you drive stepping motors with a pair of 90 degrees out of phase sine waves (sine plus cosine) you will often find the motion to be much smoother (I assume you would have 2 phase motors). I suggest selecting motors with finer steps, 200 per revolution or more. I have seen 400 to 500 step, two phase motors in applications like plotters but you will need some luck or patience to find these; however, 200 ought to be good enough. Bob At 11:57 24.09.02 +0200, you wrote: David, I want to make a round shot camera on 120 films. I got a 28mm lens 42mm mount that should be ok to start with. I already know how to make the film slide synchronised but I'm still stuck on the choice of the motor. ( yes I want to use a motor ! ) First I wanted to use a step motor + gears but I'm afraid about the lines it could make on the film. The second choice is a geared DC motor but how will I have an accurate positioning ? I thought about coupling a 360° pot or using a perforated disk with sensors kinda like in a mouse. I'll drive the motor with a microprocessor, PIC or basic stamp. I prefer the step motor because it's easier for me to drive it. For now I'm just at the draft drawing point, trying to put all my ideas on paper but I hope I'll soon have a prototype. I already made a few draws. The first ones where what I wanted to have but now I'm drawing something that looks like what I want but easier to build with the tools I have and the materials I can afford. I try to make it compact, easy to build, easy to use and not very expensive. That a tricky exercise ! I'll also try to include the possibility to switch from 28 mm to 50 mm if I have time to look for a solution of easy switching gears. Regards, Cedric. On Mon, 23 Sep 2002 19:39:21 -0700 (PDT), david hajjab wrote: Cedric, What type of panoramic camera do you want to make? David __ Do you Yahoo!? New DSL Internet Access from SBC Yahoo! http://sbc.yahoo.com ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers -- Cedric Malitte, [EMAIL PROTECTED] on 24/09/2002 ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] fluorescent lamps for b/w LF cold head enlarger
I am not sure I understand the need for a full spectrum source for black and white though I agree one must consider the spectrum with more care for color work. If you are not using multi-contrast paper I would think a bluer lamp would look good and a lot of inexpensive fluorescent lamps ought to fill the bill. For multi-contrast papers you must be sure the required spectral components are there but my intuition suggests just a couple (or maybe a few!) selected lines would be sufficient) (A few might come into play if the emulsions have more than two components to gain wide contrast range.) More than likely is it that a couple well positioned lines could increase the available contrast range by avoiding overlap of the spectral responses of the low-contrast and the high contrast components. You would have to judge this by looking at the lamp data and the emulsion data. Any fluorescent lamp for which I have seen data tends to have some sharp line structure superimposed on a continuum. The phosphors are blended to yield the required spectrum for the application, almost always to give the eye the correct impression (Some blends seem to be aimed at machines which have special requirements and there are green lamps for copy machines, to give a single example.) The narrow lines come from the mercury discharge which excited the phosphors and some of this light leaks out with the extent of the leakage depending greatly on the lamp type. The total amount of light left in these lines is sometimes a lot and sometimes rather small (you should notice the width of spectral features and compare area under the curve in determining importance of the leakage.) Try to obtain the catalog from Osram for a nice set of graphs of the spectra. Some of you might also want to look at the POWER STAR HQI. This gives a pretty smooth spectrum from a concentrated source (possibly suitable for a condenser enlarger, although the source could be too big in the higher power types) There is a major problem; you cannot turn these lamps on and off very easily. When hot they start with great difficulty and the lifetime drops dramatically with short cycles. A shutter would be required. Conversely, maybe they are satisfactory for color work at high powers. The lamps can deliver massive powers (maybe 3500 watts input) with efficiency better than a hot filament lamp so the same input power is delivering more light. Bob At 01:01 20.09.02 -0400, you wrote: Hello: I am curious if anyone has ever used 'tri-phosphor' lamps for enlarging. I'm interested in an 8x10 enlarger for b/w only, on a budget. I started looking into low pressure pulsed xenon - lotta heat, and nearly obsolete, $100 for 750W lamp, $3000 for new commercial ballast/power supply, and it's not a friendly prospect - 52 V at about 18 amps plus 1 volt spike to ionize gas...so, I think I'll look into other approaches. Ansel Adams used massive array of logo-less incandescent lamps - heat again. I'm pondering either full spectrum fluorescent (linear tubes only as far as I know), or tri-phosphor complact fluorescent (3 spectral peaks spread out over visible spectrum depending on color temperature, 2700K, 3500 K, 4100K and 6500K available (CRI 82, but that may not be relevant to film). I got spectral plot of the 6500K one today because I was unfamiliar with that one, and the spikey spectrum of the tri-phoshor type does make me nervous...hence my request for others' fluorescent experience. What I'm considering is using seveal GE Biax (folded tube) 18 or 27W lamps for an 8 x 10 or 11x 14 head, each driven with a high frequency electronic ballast. Driving the lamps above 15kHz eliminates the 120 Hz (100 for 50 Hz countries) flicker and produces about 15% more lumens than line frequency. I have access to a manufacturer of small electronic ballasts (I used to work there). I am considering running them from a DC supply with individual regulators so the light output could be adjusted for each lamp. My main worry is the strong spectral peaks in this type of lamp. The intent of this lamp design is that the brain is supposed to 'fill in the spectral gap', and THINK they are full spectrum lamps. Thanks in advance for responses. Murray ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Re: Resolution of Metrogon
Thanks for the advice on the center filter for the Metrogon. I actually had a different problem in mind. As I understand it a piece of flat glass adds spherical aberration. Someone in this group reported that the Metrogon was calculated with this in mind by including compensating aberration of the opposite sign so optimum resolution would be reached when one of the center filters was in place. (These things are pretty thick.) Conversely, I have a publication (in fact, two of them) giving data for the glasses, radii and spacings of the Metrogon and neither mentions any filter. Then again, just because the published designs do not include a center filter does not mean BL did not tweak the design for the military optics. Thus, I simply have no idea how much difference the filter makes and, sadly, I have never seen a clear center filter for these lenses. What you report on the importance of uniform exposure is very revealing and makes clear why looking only at resolution data is a mistake and the whole situation must be considered in the context of making real photos. Thanks again! Bob At 17:42 01.09.02 -0500, you wrote: resolution could actually be higher with the center filter, since excess exposure (1 stop) can cost you 20% or more of resolution potential, per example tests cited at http://medfmt.8k.com/mf/lenstest.html by Roger Hicks in Jan 2002 Shutterbug in testing wide angle 21mm on Pan F film. If the center filter enabled uniform exposure without a center highlight, you would avoid these losses (and more likely 2 or more stops overexposed without the filter, so even more of a resolution hit?). The losses from a decent flat filter to MTF is on the order of 2% or so for a good filter, and for a cheapy no-name not so flat filter, maybe 10% at high end, per Erwin Puts estimate (he is a noted Leica lens testing guru etc. However, this assumes that any focus shifting effects of the filter are compensated in setup. I find this a bit disconcerting (and not often discussed, hence notable), as it means relatively minor exposure errors or differences between systems (and by implications, developing differences between runs) can have as much of an impact on lens test results as the differences between mfgers (e.g. Leitz R vs Nikon etc. ) ;-) But my bet would be that the impact and benefit from avoiding over/under exposure would outweigh the minor losses from the filter itself... * Robert Monaghan POB752182 So. Methodist Univ., Dallas Tx 75275 * * Third Party 35mm Lenses: http://medfmt.8k.com/third/index.html * * Medium Format Cameras: http://medfmt.8k.com/mf/index.html * ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Resolution of Metrogon, with and without filter
Does anybody have an idea about how much the price is for using a Metrogon in one configuration versus the other, i.e., with or without the proper center filter? I do not refer to loss of uniformity but degradation of the resolution or MTF values. Bob ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] ? regarding apertures -- schematic..
Dear Joel, I did once find such a diaphragm and you will never guess what it was doing. It was an aperture for a fan. Please do not ask why it was done this way. I doubt that it is a full 2 feet in diameter, but more than 1 foot is possible. In any case, on such a large scale I agree making it is less frightening. I would not like filing all those little slots, but some big ones sounds far easier. I might be able to photograph a diaphragm when you do not turn up a model, but there must be drawings in books (Focal Encyclopedia?). Bob At 10:58 28.08.02 -0400, you wrote: Bob, I would scavenge for a large iris aperture as you suggested, however, i am scaling everything up (very large, about a 2 foot opening.. it's a long story ; ), so it should be easier at a larger scale. I don't know of any application that someone might have needed a monster diaphram for (except maybe military), and it is necessary that it be hand-built. thanks! joel ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Film Holders: What and where can we post?
The dimensions of the film holders are valuable information to anyone making his own camera and it would be nice if the group had them available to all. They are published (up to 8x19, at least) as ASA data sheets but these are not all that easy to get. Is there any chance to post them for all? Which really boils down to two different questions 1) Are the data sheets from the ASA copyright protected are is it forbidden to publish a direct copy? 2) Where would they be posted? (Most useful is the drawing which explains the definitions in the table of dimensions for the various formats, but where can such a table be posted?) I cannot do it because I have no server in operation. Bob ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Film Holders: What and where can we post?
I will try to scan what I have, unless somebody else has a better source with somewhat better reproductions. What I have has been reduced in size and might not survive enlarging and scanning so well, but I will try unless somebody gets there first with better material. Bob At 08:58 22.08.02 -0600, you wrote: On Thu, 22 Aug 2002, Robert Mueller wrote: to all. They are published (up to 8x19, at least) as ASA data sheets but these are not all that easy to get. Is there any chance to post them for all? Most definitely yes! Which really boils down to two different questions 1) Are the data sheets from the ASA copyright protected are is it forbidden to publish a direct copy? Figuring this out is probably the biggest hurdle we'd face. 2) Where would they be posted? (Most useful is the drawing which explains the definitions in the table of dimensions for the various formats, but where can such a table be posted?) There is a web page setup in parallel with this mailing list located at http://rmp.opusis.com/cameramakers/cameramakers.html It needs some work, but this is an available location that would make some sense. - Wayde ([EMAIL PROTECTED]) ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Re: Film holder/gr glass measurements
Thanks --Michael [EMAIL PROTECTED] for the up-to-date data. My source is ancient and lacks tolerances (I think!) However, I question one detail below: The ANSI standard for the depth of a standard 4 x 5 inch film holder is 0.197 plus minus 0.007. Most film has a base of 0.007 . When film is loaded in the film holder, the depth is 0.190. This is the measurement used by Sinar cameras. Wisner cameras use a compromise of 0.192 to allow for wear on the wood and because Tech Pan film, used by some photographers to achieve ultra-sharp images, has a base of 0.004. ### I infer from this that you must add a correction depending on the thickness of the film base but I believe this is wrong, at least for the film holders I know. The location of the film plane is set by a narrow ridge around the edge of the film. The film is pressed forward against this fixed ridge by a movable pressure plate until it contacts the fixed rige. It is the emulsion which is then at the location of the ridge surface and the location will be independent of the base thickness. You might consider a correction for emulsion thickness but that will be far below the tolerance band except for some unusual film, and even with such a film I might select forming a sharp image at the surface, where diffusion in the emulsion has not yet taken its toll. The only time one should even begin considering the base thickness is with a film lacking an anti-halation backing or tinted base, both of which surpress reflections from the back of the film. Or, one other special case, the vacuum back. Here it depends on how the film is located. If the film still presses against that ridge and the vacuum back floats to conform to the ridge location, nothing will be changed. In the big repro cameras I have seen in use, the back is fixed and arbitrary size film is sucked against the plate. The location of the back does not change to accomodate the film thickness and here a correction will be needed. As for the tolerance band, I would try to stay closer to the 0.190; if my back-of-the-envelope calculation (based on simple geometrical considerations) an error of 0.007 inch will degrade the resolution considerably at F4, and if you are lucky enough to have an F2.8 lens for 4x5 (Aero Ektar or Schneider Xenon, at 2.8) and wish to photograph at full aperture, you will be reaching much less than the capabilities of the lens (50 lp/mm or better, and with the Aero Ektar, I believe well over 100 lp/mm, so the film is limiting if you focus well, which you can hardly do with sloppy 0.00 inch errors!) Bob Bob ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] ground glass spacing relative to film plane
The desired location for the ground glass is easy to state. The rough side should face the lens (normally, anyway), and lie at the same place as the emulsion of the film during the exposure, while composing and focusing. For normal film holders you must then measure (or look up somewhere) the distance of the film emulsion from the surface of the camera against which the front of the film holder is pressed (i.e., measure on a film holder. I wish I could add a sketch here!!) When there is no film in the holder, the pressure plate will be at the same location as the emulsion when the film is later inserted. If you have some odd film holder for which this is not true, just waste one sheet film as a test and study object. One case would be somebody using a vacuum holder; depending on the design, the vacuum plate itself could be somewhat removed from the ultimate emulsion plane. Bob At 18:07 16.08.02 -0400, you wrote: Hello: This has probably been asked, discussed, etc. many times before, and maybe I've already asked. I haven't built a camera yet...still collecting parts and so on. If someone can please refer me to a website that discusses the requirements for spacing ground glass relative to the film holder focal plane, I will have a 'permanent' answer. Of course, replies to the list are appreciated...I think they get lost in my archives, and eventually when I start thinking about how to do something, I end up asking again. Since my wife I own a gallery frame shop, I have access to finished mouldings that would, in my opinion, make suitable standards for a view camera, and that's the direction I want to pursue. I usually see requests for sources of camera hardware, presumably 'proper hardware'...I am curious what people have adapted from others arenas to accomplish rise and tilt shift. Cosmetics are NOT especially important to me...I get satisfaction out of getting good results from ugliness. Thanks Murray Thanks Murray ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Re: Printing on non-silver emulsions of low sensitivity
Does it really make any difference whether the plate is made of glass or, say, Mylar? The substrate can almost surely tolerate higher temperatures than the emulsion. Mylar holds up even at 200 degrees C. I would make no bets on gelatin at this temperature. Can't you use a variety of films for reversal processing? I thought it works with Tri-X and maybe also Plus-X and I suspect with many others. (Perhaps the problem here is that I know of Tri-X used this way in movie film sizes and maybe the larger format emulsions share only the name but not the characteristics!) These may not yield quite the high resolution of the films intended for the job, but how much resolution does a large format negative need for projection printing on fabric? You are correct that ALL light will end up as heat, somewhere. Conversely, there is a lot of power per unit area in the useless (for this task) parts of the spectrum of the sun. Not only is the infra-red without benefit, probably anything longer than the green wavelengths contribute little to the exposure. However, it is probably easiest to find or make an anti-IR filter. (A lightly colored solution of copper sulfate between a pair of good quality glass plates will remove a lot of IR while letting, through most of the useful light. A lot of bother but a valuable method when large sheets of heat-absorbing glass are hard to obtain or pay for.) With filtration the heat load on the film will drop dramatically. Bob At 14:26 09.08.02 +0800, you wrote: At 2002/8/9 12:44:00, you wrote: I will do some tests this coming week. Would be interesting to find out the ratio it will take an enlarged neg to expose the paper as opposed to contact. I guess one could calulate it, but I will just do some real world tests. This suggestion probably comes too late or has some elements of impracticality, but you might relieve some of your problems if you would work from an enlarged negative; 8 x 10 would be desirable, but even 5 x 7 or 4 x 5 would be a big help. How you you make such a negative? I haven't checked Eastman's current product list, but they used to make a direct-duplicating film in a wide range of sizes. If they don't, you could use Commercial Ortho or an equivalent emulsion and process it by reversal. It is not usually mentioned, but it is possible to use carbon printing techniques to make a transparency. (I have used carbro to make a color transparency _on glass._) I don't say that this is easy, but by an admittedly tedious process, you could end up with a negative on, for example, 1/4-inch plate glass, perhaps even Pyrex. _That_ ought to take the heat. Such an enlarged negative would of course reduce the required exposure, but just as importantly it would reduce the radiant energy (which eventually translates as heat) per unit area. No matter what filtration you use or the amount of cooling air applied to the negative, any light, visible or in the ultraviolet region, eventually ends up as heat. I once wrote someone in this group a description of an enlarger that was used to make offset printing plates (about 20 in. x 24 in.) from negatives about 7 in. x 15 in. The light source was a carbon arc concentrated by a set of condensor lenses; the negative was able to withstand this punishment because it was a glass plate. (I never did receive an acknowledgment of my message, so I don't know whether it was of any help.) Mac George Arndt ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] High Resolution film (Black and White)
http://www.gigabitfilm.de/download/datasheet_small_format.pdf http://www.gigabitfilm.de/html/english/technical_information/descriptions.htm Some of you enjoy pushing the art of photography as far as possible and the above pages might provide help if you desire maximum sharpness for your photos or for testing lenses. (Many test results are limited not by the lens but by the film; here is a way to largely eliminate this limit.) Bob ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Surplus Military lenses??
Look at Surplus Shed for military lenses. I would look for something with larger aperture (not a Metrogon) and normal viewing angle. You might also look for projection lenses of the kind used for opaque projectors (I doubt anyone makes these anymore and probably few persons still use them, so you might be able to buy a projector or lens cheaply.) These had reasonably long focal lengths, were corrected for less than infinity object distance and had fair aperture (maybe F4 or so). You might look at Fresnel lenses as condensers. Bob At 20:24 08.08.02 -0700, you wrote: Greetings! I have a project and would appreciate some suggestions. I need to build a SOLAR ENLARGER. Basically a Daylab type enlarger, that can project a 120 negative (in a glass holder) onto a surface as wide as 48. The light source will be the sun. the reason, i need to expose a cyanotype print. I would like to find a surplus lens, maybe a military arial type lens? Any advice or where to look? What about focusing? I was also thinking that I could use mirrors to focus more light into the enlarger. Any ideas? i can't contact print the cyanotype with an enlarged neg because the surface is not flat. Thanks Mac ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Surplus Military lenses??
? A proper lens takes the light coming from the object (the film in this case) and projects it in a way such that all light coming from a single point, whatever its direction of travel, will end up at a single point on the image (the fabric). Assumed is that the system is correctly focused. Wandering of the sun does not change this; a single point on the source will be projected to a single point in the image throughout the wandering of the sun. However, there is a different trouble; rather quickly the sunlight through a given point will not hit the lens so that point in the image will go dark. The nicest solution is what I believe is called a heliostat. This has a mirror which tracks the sun's motion in a way so the light is cast in the direction of the lens a the sun wanders through the sky. You could do it by hand until you determine whether making a real tracking machine is worth the bother. Please note, the sunlight comes from a constant direction when this device is in use, no matter where the sun actually is (if not below the horizon or behind a cloud!) There is a different problem as well. You more or less need a condenser unless the lens is bigger than the film. Sunlight travels as a nearly parallel bundle of rays. Only light passing through a circle the size of the lens but lying in the plane of the negative actually passes through the lens. You can move this circle over the film but only this much negative is being exposed at any time. Without a condenser you will have to scan the film by passing the light from various directions through the lens so the whole film is roughly equally sampled. I suggest adding apiece of heat absorbing glass if you can find one in the right size; for a 2x2 negative it should be relatively easy. Bigger will be harder and more expensive. Bob At 08:49 09.08.02 -0700, you wrote: Another thought... If you are exposing for a long period of time the position of the sun may play a huge factor on your enlargement with out a condenser. Take a flash light and move it 25 degrees across film and see what it does to the final image on the wall... A guess would be that the image will move right along with the light thus ruining your print... John I thought about that, but there would be a piece of diffused glass between the sun and neg. ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Surplus Military lenses??
Diffusion glass will do the job as well but with the cost of considerable light loss, which might be important when exposures are getting to look like hours. Bob At 08:49 09.08.02 -0700, you wrote: Another thought... If you are exposing for a long period of time the position of the sun may play a huge factor on your enlargement with out a condenser. Take a flash light and move it 25 degrees across film and see what it does to the final image on the wall... A guess would be that the image will move right along with the light thus ruining your print... John I thought about that, but there would be a piece of diffused glass between the sun and neg. ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] film holder dimentions
Dear Pierre, Where are you? I assume either France of Canada, but maybe it is somewhere else. Anyway, I have an ancient book giving these dimensions with a drawing. If you are in Europe I will mail you a copy of the appropriate pages. If you are in North America I am sure somebody there has the same book and will gladly do the same (won't you?!) Please give a mailing address where the copies should be sent and I will try to have them out in a couple days. (You can email me directly and save posting the message to everybody when it is really only for my attention.) Bob [EMAIL PROTECTED] At 02:04 03.08.02 -0700, you wrote: I recently started to build a 4x5 field camera from scratch. Since I don't have any film holder at the moment, I would need the exact dimentions of an elite fidelity film holder (outside dimention, film window,etc...) to desing the back of my camera. If anyone from cameramaker could sen me these information (metric please) If would be of a great help. = Pierre Bize __ Do You Yahoo!? Yahoo! Health - Feel better, live better http://health.yahoo.com ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Price of 8x10 film
Just a question based on the statement below about litho film. Litho film lacks tonal range when it is processed in litho developers. How does the range look when processing is in more conventional (lower contrast) developers? It may still be poor if I am right that part of the secret of litho emulsions is more uniform size of the silver salt crystals, which in other films is made more variable to gain tonal range. Conversely, maybe the very fine grain of the litho emulsions is worth some loss of tonal range and maybe there is artistic potential in the unusual exposure versus density curves. Does anybody have the experience to clarify all this? Bob At 22:42 04.06.02 -0700, you wrote: Just thought I would let y'all know about a film I came across. Photo Warehouse of Oxnard CA (1-800-922-5484) carries what they call a fine grain positive film in 8x10 for about $10 for 25 sheets. To quote: Fine Grain Positive Film. Use like enlarging paper. Will yield a black and white transparency from a negative. Use standard paper developer and safelight. There are two thicknesses. The thicker is 12.95/25 sheets for .007 poly base. I have not used this film in a camera - it is obviously not panchromatic and would probably be ISO 6 or so, but it has a full tonal range unlike litho film. I have used the film to make transparencies for an art class. They also carry ISO 125 8x10 for about $37 for 25 sheets and they carry Cirkut camera film in two sizes for a lot of money. They also have a dbl wt fiberbase varigrade warm tone 8x10 paper for $8 for 25 sheets (made in England). I am not affiliated with them but thought some of the project people here would like to know about the resource. __ Do You Yahoo!? Yahoo! - Official partner of 2002 FIFA World Cup http://fifaworldcup.yahoo.com ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Flat Bed Camera Design in EIM, NOW!
Yesterday my newest issue of Engineering in Miniature arrived and it contains an article of probable interest to some readers of this group. It is the first installment of The Korekta 5x4 Flat Bed Camera. Because this magazine is not much oriented toward cameras as construction projects, but rather concerns itself with a wide range of model making and home machining, I suspect few users of this group subscribe so here I will tip you off! The author is Richard Church and the camera is made from wood, Al alloy and some plastic ( Nylon Rack and pinion, at least.) I would describe the design as utilitarian rather than elegant in final appearance (Good plywood is a wonderful material, often lacking in the beauty of fine hardwoods but blessed with stability, sturdiness and availability.), though hardwoods are employed where they bring benefits. Bellowsmaking is not involved; the author suggests buying and you all know where there are articles in the Internet for DIY bellows. The camera includes a good range of movements (In front, swings and tilts plus horizontal and vertical sliding motions; in the rear, only the rise and fall are absent.) I will leave it to others with experience to evaluate in more detail, but to me the camera looks like a relatively easy one to make yet offering enough flexibility to satisfy most demands. It looks as if the design enables good performance without too much time spent on non-utilitarian aspects. It's for making pictures rather than for looking at the camera itself! EIM is a British magazine distributed in the USA to subscribers and maybe you can turn up an issue at specialist magazine stores, but I suggest writing to the UK publisher if you are in an area lacking a source (there is an address given in the magazine for the American distributor, but no phone number, and no suggestion the company handles orders for anything.) The UK email address is [EMAIL PROTECTED] . There is also a site http://www.fotec.co.uk/mehs/tee which I will be checking out after finishing this! I recommend that the first person who determines how to obtain the desired issues (there is at least one more installment a month in the future, but the first already contains a good fraction of the details and drawings, However, the back is not yet described.) Perhaps this magazine is a good outlet for those who have made cameras and who wish to share their designs with the rest of the world. The readers are often first-rate craftsmen and some will be building just to have an ideal camera for photographing their wonderfully detailed locomotives, etc.. Your designs might infect them with a new activity, serious photography. Bob ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Contact cement on bellows
I just saw the very nice site on the construction of an 8x10 camera and had a suggestion. In the text it is mentioned contact cement was not successful as an adhesive. I am not too surprised because this stuff is horrible to apply as a thin and uniform coat using a brush or other obvious method. However, spraying seems to work, using the cement offered in spray cans. It is more expensive than the normal kind, but the extra cost is worth it, I think. Contact cement is robust and flexible, making a quite strong bond. As far as I have seen, it stays functional for a long time (I would not be happy to have my bellows fall apart because the wrong cement dried up after just a year or two.) It also has the virtue of drying before the bond is closed, a potential problem with solvent evaporation cements used with non-porous bellows coverings. One problem which must be solved is the keeping the spray from blowing away the little reinforcement/stiffener strips which some of you will be using. I hold them down with fine monofilament fishing line or sewing thread. There are surely other ways but this one is easy enough. I have also been tempted to try silicone as a glue. It has one nasty feature; it forms a film very quickly and I worry about whether the joint will be good if such a film develops. Conversely, this is a material which ages very gracefully and it is very flexible. It can be thinned (naphtha or white spirit) but it tends to be viscous unless very heavily thinned. (I believe the solution is thixotropic.) (If I spelled that wrong, please forgive me and let us know what is correct; my spelling checker doesn't know the word and neither does my Spelling Ace!) It should be ok if you can close the joint quickly after application of the silicone. Bob ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Ilex 10 lens elements
I am not sure I understand the comment Betcha they weren't polished to as good a figure If they were not well figured, how did they reach diffraction-limited performance (as has been reported in previous postings in this series)? Conversely, who needs the better figure if diffraction-limited performance is achieved with less?!!! Bob At 22:01 21.03.02 -0500, you wrote: The elements have a 76cm diameter, We are talking about some serious glass here!!! ;) bye, sid. Yes, I have sat at barroom tables of a lesser diameter! RKS Betcha they wern't polished to as good a figure (although I have seen a few that would make a good blank for a mirror) bye, sid. ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] AutoCAD shutter file?
In my computer! But I can send you the file. Please understand; it is ONLY a drawing of the blades for use in etching to cut out the thin pieces without damage likely to come from mechanical cutting methods. I do have the mechanical driver but that was done without AutoCad (I did not even have a PC then.) I can make you a sketch in AutoCad; it is a pretty simple thing but seems to work well (I used to test it by running it on a function generator to make it rapidly open and close the shutter. For the small blades needed for a Metrogon I could reach good speeds, maybe 1/100, though that was a long time ago and my memory might be wrong.) Let me know whether you need the additional sketch and feel free to remind me about the blades (I am under stress and probably will forget! In two days all will be more relaxed and then I can do it! Bob At 20:08 20.03.02 -0800, you wrote: Where might I find the AutoCAD file you mention of a shutter?? TIA Will ---William Nettles [EMAIL PROTECTED] Nettles Photo / Imaging Site http://www.wgn.net/~nettles Find out what's happening in Echo Park: [EMAIL PROTECTED] From: [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] Date: Tue, 12 Mar 2002 12:07:06 -0700 To: [EMAIL PROTECTED] Subject: Cameramakers digest, Vol 1 #361 - 1 msg ell, yes, almost! I have done many of the steps in making a shutter to be controlled electronically. Indeed, there is an AutoCad file of the blade shape and I also had the electromechanical parts up and running on the blades of an old Ansco lens. This was a two blade type but they are not all that bad and in smaller sizes can do faster than 1/100 sec, a ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Ilex 10 lens elements
You do mean 76 mm diameter, I believe. That is already pretty big but sounds about right for F4.5 in 10 focal length. Bob At 21:38 20.03.02 -0800, you wrote: Hi there, ho there! I've just picked up a set of Ilex Paragon Anastigmat 4.5/10 (254mm) elements without a barrel or a shutter... So I have a couple of questions: Could I make a barrel attach the whole thing on a board with a Packard shutter? If this sounds workable- then, what should I use to make the barrel how do I figure the distance from the front to rear elements? If this gets to be too complicated/expensive I would probably want to pick up a shutter... anyone know which shutter would fit for these elements? The elements have a 76cm diameter, not sure of the thread. Thanks! John Moore Ramona, CA __ Do You Yahoo!? Yahoo! Movies - coverage of the 74th Academy Awards® http://movies.yahoo.com/ ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Homebrew shutters
Well, yes, almost! I have done many of the steps in making a shutter to be controlled electronically. Indeed, there is an AutoCad file of the blade shape and I also had the electromechanical parts up and running on the blades of an old Ansco lens. This was a two blade type but they are not all that bad and in smaller sizes can do faster than 1/100 sec, and I wasn't really trying. The electronic controller is no problem and one has great flexibility in the design, but I have never actually built it, though there are schematics in the drawer. That is an old story and I might consider doing it with a microprocessor if I were designing it today. They cost so little and can give great flexibility and precision without much effort (a little programming and a little less solder.) (If you coupled in the diaphragm opening you could correct the fast speeds to yield constant effective exposure with opening, for example. Of course, you would need a way for the processor to know the opening, but that just adds to your fun in making the thing. The easiest way to get a decent shape for the blades is plagiarism! Just enlarge the blades of a good example. These shutters are especially easy to drive. (The three and more blade types usually run from a rotating ring and the total effort is substantial.) I would make the blades from shim stock, blackened, and shaped by photoetching. Cutting thin stock without rolling up the edges is not so easy, though you can master it. With photoetching it does not happen. Bob At 10:30 11.03.02 -0500, you wrote: Hello: Has anyone here ever accomplished or considered a homebrew shutter? I'm thinking linear or rotary focal plane or 'venetian blind' louver kind of thing. Electric/electronic is fine with me...I've got a pretty good understanding now of how the electric shutters work (except for deciding how to interpreting/averaging the opening and closing time relative to the effective exposure time). Someone's loaning me a 'Speedcomputer' shutter controller to 'study'. I have one of those Aero-Ektar 309 mm f/2.5 giant lenses and because of it's 'speed' it'll need a relatively fast shutter unless I just want to do nighttime work! Thanks - Murray ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Cheapo Helicoid' focuser
Thanks; it always looked so formidable that I was frightened off. If it is hardly worse than a single start thread, it is well worth considering. I appreciate the encouragement, and still worry, but less! Bob At 21:03 24.02.02 -0500, you wrote: Re;Barry Young [EMAIL PROTECTED] The second time you do a multistart thread it is cake. You, Sir, also speak from knowledge. bye, sid. ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Cheapo Helicoid' focuser
Dear Barry, Perhaps you have some advice on getting the depth correct. The obvious solution is wires, for the outside thread (except for those who are lucky enough to have a thread micrometer.) How is the mating inside thread monitored for depth? This is the operation which was my worry when expressing concern. With a single start thread you can advance in small steps, using the outside thread as a gauge. With four starts that is a little trickier; you have to cut all four, test, and if more metal must be removed, repeat. Conversely, if one can measure, there is no big problem in advancing the tool the right amount. Unfortunately, I have never even seen a micrometer for inner threads! You advice will be welcomed by all who might have to face this problem. Bob At 15:22 24.02.02 -0800, you wrote: Hi Robert: Most multi start threads used in photographic equipment use three or four starts. All I have made as replacements have been 4 starts. This is easily indexed using a machined block under each of the jaws on the four jaw chuck. You can do it, only the first one is difficult. The second time you do a multistart thread it is cake. All the focusing helicals I have seen have 60 degree included angle thread flanks. Barry Young ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Re:Helicoid focus
It has been a long time since I lived in the USA and so I do not know all the possibilities to fulfill this suggestion, but here I see very cheap lenses for 35 mm cameras now and then. The condition may be bad, but if you want the mount and the glass is bad, who cares!!! There is a problem; these mounts may be rather long and may be badly suited to an extreme wide angle lens. You may even not be able to judge the true diameter of the hole you will have left after the glass is gone. Still, you do get the nice thread and maybe a lot more. With some imagination adapted to what you pick up you might be able to rescue enough of the real thing to solve your problem very efficiently. My guess is that an ancient WA has small diameter elements unless it was made for a pretty large format. If you find nothing at garage sales or flea markets, try begging! You local photo shop might offer you some junk too bad to sell and not worth fixing because it would never bring the cost of improvement. Get several, take them apart and select the one best suited for this problem and save the rest for other glass. Bob At 20:16 21.02.02 -0500, you wrote: Is there a hardware store item that I can use to focus my 100-year old extreme wide angle lens which I plan to use as a 5 X 7 point-n-shoot? Marty Hi to All: This is not really a hardware store item and is relatively more expensive but not prohibitively so The Pentax 6X7 helicoid extension tube which can be had for $100 + or - . Just make a lensboard to attach to the front of it ect. ect.-- scribe a focusing scale on it- ect. I have not done it, but think it very feasible! Regards, LARRY (nieland) ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Test of Aero Ektar 178 mm
There is somebody offering an Aero Ektar at ebay http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItemitem=1334394605 I believe anybody who can read the German text might enjoy the information. Indeed, you can probably guess enough to make sense out of the numerical values even without reading German. I was amazed how good this lens is and the report might encourage some of you to grab the first one offered to you. After remounting in a shutter (or with a Packard), this lens ought to satisfy the needs of almost all doing 4x5 (9cmx12cm) on a shoestring. And how many of us can even find alternatives offering F2.5 for 4x5 format? What I also hope is that some reader of this group might have a source of the entire report from Hubble. The test results in all their detail would be nice to have and according to the ebay seller, the Hubble report compared various aerial lenses. You would be doing all of us a service if you could supply a copy of the report to anyone wanting it. I, for one would gladly pay a bit for a photocopy, postage and other costs of the person who can get hands on this document and distribute it. The sad news is that Surplus Shed does not currently have any to sell to you, but they will no doubt again appear. I am thankful to have mine, already, but now I am driven to remount it! Bob ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re:Proposal for headers [Cameramakers] Re: Cameramakers digest, Vol 1 #346 - 3 msgs
To any and all, I favor using the original header for these messages, provided it describes the main content. But does Cameramakers Digest . really give any clue ? Bob At 21:22 20.02.02 -0800, you wrote: Very interesting. Could you send me an image of the lights adapted as an enlarger light source. From: [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] Date: Wed, 20 Feb 2002 12:07:09 -0700 To: [EMAIL PROTECTED] Subject: Cameramakers digest, Vol 1 #346 - 3 msgs To: [EMAIL PROTECTED] Subject: [Cameramakers] Copier/Enlarger lenses Reply-To: [EMAIL PROTECTED] Are all the copier lenses plastic? I'm sure they are worth a couple of bucks, but they can't be very sharp. At some point what reason is there for shooting 8x10? Also on the enlarger lamp subject. I've been building snoots and reflectors for my Lowell Lights. I recently need to have two lights on the floor pointing at the ceiling for bounce light. Instead of the using the Lowell DPs which spill light all over the place for $10 each I bought 3200 k blbs for my Home Depot work-lights and quickly cobbled together a couple of sheet metal snoots. Worked fine. I now plan to make a 250/500 watt enlarger head out of the smaller Home Depot lights and sheet metal. By making a diffusion source almost all of the heat is kept off the neg stage. (the two wattages would be from using two lights. They would be hooked up to different timers. I have some negs from China that are really dense and print with 150 watts at 3 minutes. I may be 'welding with light' but careful design and distance should allow light without too much heat.) What do you mean by diffusion source? I found that using .032 aluminium sheets instead of the thin .010 rolls of roof flashing I can make much more durable housings. Also because I have a 135mm lens for my 4x5 negs I plan to get a thinker sheet of translucent plex and sand down the edges to counter light fall off caused by the slieght wide angle of the lens. Will ---William Nettles ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Helical focusing
If you do not mind having the lens rotate (annoying but not unbearable) you can try some plumbing components and especially drain components. They have a fine thread on thin walled tubes of brass (maybe chromed for Beauty (if you like that sort of appearance on you photo stuff!). Bob PS Here we get electrical conduit with a similar thread. This is steel At 01:07 21.02.02 -0500, you wrote: Is there a hardware store item that I can use to focus my 100-year old extreme wide angle lens which I plan to use as a 5 X 7 point-n-shoot? Marty ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Enlarger lights, focusing motors, books etc...
In short, the small, inexpensive, gear-reduced, reversible, 3-wire capacitor run motor is by far the simplest way to go. Have fun, bye, sid. Perhaps, but almost as easy is a DC motor with a gearbox. The beauty of it is the ease of reversal (reverse polarity of power) and the ease of speed control, so the last bit of adjustment can be done at a small speed (maybe with a potentiometer to vary the speed.) Bob ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: 12 Metrogon, was Re: [Cameramakers] Metrogon Astrocamera
If I were doing this I would not use a Metrogon! I like the Metrogon and own three 6 inch ones, but I doubt that it is the best lens for the job I understand you want to do. Let me try to explain. Wide-field aerial lenses are designed to achieve various properties over a wide angle of view, often 100 degrees or more, and your Metrogon probably covers something like a 24 inch diameter circle with a fairly good image. The properties wanted in such a lens are (to name a few) 1) sufficient speed to expose with shutter times appropriate for a camera in a moving aircraft (with some cameras including some motion compensation to maintain sharp images while flying) 2) Relatively low distortion (often, but not always!) because the films are evaluated for the location of the the objects appearing on them. (There is at least one aerial lens which deliberately produced a distorted image as the price for a more uniform lighting of the film, with the print being made in a way which corrected the distortions.) 3)decent sharpness over the whole film. The trouble is that decent sharpness over the large angle is paid for by giving up the best possible sharpness at the center. The center is likely to be no more important than the object at the edges, so the designer compromises. Now consider a telescope. You might be planning eyepieces as large as 2 inches diameter (and I think it is possible to buy bigger), but they would see only a tiny part of that 24 inch circle. Conversely, even a narrow view lens designed to maintain great sharpness on, let us say, a 2 inch circle, could offer you more resolution and speed at the same time. Lens design simply gets harder and requires more compromise and cleverness when one attempts to include rays at considerable angles to the optical axis of the lens. In fact, I think normal telescope lenses have a chance of covering the hypothetical 2 inch circle with nearly diffraction limited resolution, but they are likely to be about F15, far slower tan your Metrogon. However, something like a Tessar probably delivers nearly diffraction limited images at the center and at maybe close to F4.5, or at least when stopped down a bit. Now put into the argument that you will be using low power eyepieces to maintain the wide-field property; with a low-power eyepiece you will not easily detect defects in resolution such that the objective is somewhat worse than diffraction-limited. This would no longer be true if you go to short focal length eyepieces, but then you have given up wide-fields and we are discussing a different problem (and one for which the Metrogon is even less well suited!) In short, you can do it, but by giving up the Metrogon you can easily do it better. On the other hand, some authors report that the Metrogon is good for make photos covering a large portion of the sky. I think folks looking for meteors might be tempted by them (though if I were doing that today I would probably use 35 mm lenses, a CCD camera and computer data processing). Well, I have written a book. Others may offer contrary points of view, but I hope you grasp my grounds for doubt. Bob PS If you can get your hands on a good optical program you can get fair ideas about the resolution of many common lenses. I am using an old version of ZEMAX; the Metrogon is not included as a sample but the data are available so you can enter it. In this way you can compute the quality of the images before investing in a particular type of lens. This is not 100% certain; different makers may tweak the compromises in their products differently and to do a really good comparison you would need real data for the make of lens you are considering, and you will rarely get that. It would be far wiser to just test an example! Also, testing avoids deviations from ideal caused by manufacturing tolerances. None-the-less, the computed results will give you a good idea whether a particular lens class has even a chance to meet your desires! If the ideal lens is inferior to another type, you probably should switch! The programs are expensive but some are offered as Demo versions which are limited but still pretty powerful. One serious limitation is that they only work with the lens designs offered as examples. If it does not come with a Metrogon you are out of luck, unless you are lucky to discover some way to get around the limits. At 21:50 17.01.02 -0500, you wrote: Another Metrogon question. I own a 12 f/6.3 Metrogon and have a similar interest, i.e. using the lens to build a wide field telescope. Would also appreciate any advice others might have on this project. Thanks. Sandy King Hello Everyone- I'd like to try my hand at building a camera for meteor photography. I have a surplus 6 inch Metrogon lens mounted in the original 6 inch diameter diaphragm/shutter assembly; my lens came with the original yellow filter. I plan to build the camera from
Re: [Cameramakers] Use of pocket Lasers with rangefinder cameras
Why must the viewfinder optics for the eye be shared with the laser? Just put the laser below or above, though as near as possible. Of course. magnification can be included. With separation you have no danger to the eye except maybe if you measure the distance to a mirror! Bob At 20:09 17.12.01 -0500, you wrote: Robert Stoddard wrote: Marv, As I recall the Focuspot, the light source sat on the top end of the vertically mounted RF and shone its light through a little transparent port directly along the axis of the RF. Because of the beam-splitter mirror, half of the light emerged from the top window of the RF, half through the bottom window. When the camera was focused, the two beams converged on the subject. If you are putting your laser light source in the same location, then how is there any danger of light coming out the eyepiece? RKS From: Marv Soloff [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: [EMAIL PROTECTED] [EMAIL PROTECTED] Subject: [Cameramakers] Use of pocket Lasers with rangefinder cameras Date: Mon, 17 Dec 2001 18:01:51 -0500 Had an opportunity to buy a handfull of pocket lasers the other day. These are marketed as a laser keychain and measure 2-1/2 long by 1/2 in diameter. I had remembered that Kalart made an accessory for the Kalart rangefinder equipped Graflex press cameras that used a battery and focused lamp to project a pair of light beams for focussing in low level light conditions. When Kalart manufactured its own press camera, the Kalart 3 x 4, this device was an integral part of the camera. So, the question arose - can a small laser be used thru the rangefinder port to provide low light level focus? Well, I tried it and it works. The only problem is to fabricate a fail safe blocking plate that prevents looking thru the rangefinder when the laser is in operation. Perhaps a slide switch arrangement? The cost of the keychain lasers - at the Englishtown (NJ) flea market $2.00 each including 3 LR44 batteries. Regards, Marv ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers _ MSN Photos is the easiest way to share and print your photos: http://photos.msn.com/support/worldwide.aspx ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers Just tried it on the 23 Crown Graphic - there is too much backscatter thru the viewing lens of the rangefinder for comfort. I, for one, approach lasers with great caution. The adapter will have a shutter for the viewing window coupled to the laser power switch. Regards, Marv ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Leather source?
It was asked where one can buy thin leather for bellows; I must admit it has been a few years since I bought there, but Tandy shops did have it. These seem to be moderately common; however, maybe they have all disappeared since I was there. It is likely to be a little thicker but I have bought old clothing and stripped the leather out of it. It takes patience but you can get real bargains in some high quality material. Likely items are long coats and skirts; a jacket can also yield large enough pieces but it is less likely. Conversely, good fabric is liable to last longer and be more resistant to rot, as well as being thinner, but I agree, leather does offer something special, and how many of us will outlast it? Bob ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Add Focus Ability to your Pencam
A few weeks ago I broke down and bought a pencam as a quick and dirty way to record things for the Internet and simply whenever I was underway (I used to consider a camera working on film for the job but the instant readout appeals to me.) Well; I was lucky; the images were not so good and the problem seemed like poor focus, but it looked as if a bit of a rotation of the lens mount would fix the problem, so I grabbed a pair of sturdy tweezers and gave the mount a twist (it has a pair of tiny holes probably intended for exactly this job, but at the factory) As expected, the focus was quickly corrected; so why not add an adjustment so I could focus anytime I wanted!? It worked and it's not exactly camera making but modifying is close enough. The end result focuses to about 10 cm with a full turn of the lens, allowing pretty satisfactory close-ups while the work involved is small. For those who might be tempted; 1) find or make a disk to become the handle and on which the calibration will be marked. My own was a gear from who knows what, with fine teeth. Material: cream-colored plastic. Metal would work as well, and a plain disk would be fine except the fine teeth are a nice substitute for knurling. The grip is good. I considered a washer but the only ones I had with a small hole and a suitable diameter were plated steel and I did not want the rust, but you may be luckier in locating a better one. 2) Put in a central hole of a selected size and two small holes for mounting the disk to the lens mount. On my camera the holes on the mount are 8 mm apart and have 1.2 mm diam. A different model might use other values. (I have an Aiptek Presscam.) My screws are m1.4 so the holes in the disk are 1.5 diam. 3) Deepen the holes in the lens mount. I removed the lens entirely and prayed I could guess a safe depth. I was lucky and struck no glass (I was a little afraid to remove the optics from the mount; that would be trading one kind of safety for another.) You may want to go to some UNC size if only those taps and screws are easily available. There is enough metal for holes about 3 mm or so deep, but that is a guess! Please do not just go to that depth and dash off an angry message if you bore a lens. (The back elements on my lens are much larger than the hole in the front so there is some danger.) 4) Fasten your disk to the lens. Mark the distances for best focus. I do not have a reference line; I just use the edge of the viewfinder. You can add an official reference line according to taste. The easiest method to find the sharpest focus is to run the camera as a webcam, with the highest resolution, which will probably give rather slow response on account of the readout time over the USB port. You should keep the camera quite steady to get decent images because determining sharpest focus is not all that easy. My target was an Air Force 1951 chart but there are plenty of alternatives, some of which are likely to be better. The Siemens chart could be better; bring the sharp image as near the center as possible. The lens is fixed with a spot of glue to prevent wandering out of focus in the hands of the buyer. It takes some torque to remove the lens. Don't slip! You will mark up the lens mount, a not too professional style of working (I should admit, I have those marks, though they are hidden under my disk.) Clean off the glue before installing the lens. A full revolution covers from infinity to about 10 cm on my camera, making macro work possible. You do need to correct the parallax when observing through the viewfinder. (Reminds me of the good old days, when I still had a Leica IIIF. You can get good results without an SLR or other ground glass focusing.) I was again lucky; my gear had a raised ring on one side and when this faces the camera it serves as a stop preventing me from turning much past infinity. You might want to make something similar but better is to leave a little bump on your disk and arrange a stop on the camera body so the rotation stops at infinity and is confined to a little less than 360 degrees. The final result is a considerable increase in flexibility for not much work. I looked at the resolution on the Air Force chart and it was better than 400 lines (200 line pairs), so the optics on these cameras are not bad. (It is not trivial to measure resolution beyond a certain point and I doubt that the Air Force chart is the right tool. You can reach some quite different conclusions depending on just how the chart lines are aligned with the sensors pixels. (With a steady support I and patience, I can believe you could align the pixels with lines on some chart and see 640 lines=320 line pairs in the final image, but is it worth the effort?) It is not a 5 megapixel camera but I am pleased by the photos but for about $50 I will not be too devastated if it falls into a pond or something similar. And
Re: [Cameramakers] 120 Takeup winders wanted
Several is a different story! Why not make one. A simple design I have seen depends on some bearing balls which run on little ramps. There is a drum and a disk inside it. The ramps are cut into the edge of the disk. For one direction of turning the balls roll up the ramps until they jam against the inside of the drum which is then turned. For rotation in the other direction the balls run down the ramp and bump a steep slope (vertical wall!) and so no climbing or jamming occurs. These would be quite easy to make in the quantity you want. A ratchet would be a good alternative and I believe you can buy the wheels if you do not want to bother cutting them. Bob At 21:11 30.10.01 -0800, you wrote: Well, I'm looking at doing several, so I might need a consistent setup. I want to make my own rollfilm backs. If I can't find another way, I might take you up on it. Dwight - Original Message - From: Gene Johnson [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Tuesday, October 30, 2001 9:02 PM Subject: Re: [Cameramakers] 120 Takeup winders wanted Dwight, Most of the old folders have them. If you're interested I have an old one around here somewhere that would probably do the trick. Gene ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] 120 Takeup winders wanted
Try http://www.horology.com/hoc-susu.html for some sources of parts. I saw both LaRose and Selva there. And others I suspect both have Internet sites, but I have not checked that. Bob At 08:20 31.10.01 -0800, you wrote: ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Rack and pinion template system
of steel would get us jig that could last a lifetime. Also, as I said earlier, the more of us that get one will drive the cost down as well. Also, the CNC machine will do a great job of cutting the shape of the teeth to the correct dimensions so we won't have to get too detailed about that side of the construction although I can say that the gear teeth will be typical involute gears that can be used in rack and pinions. Obviously, you won't be cutting helical or worm gears with this. So far it looks like the list is myself and Phil McCourt. I'll keep the list informed of the plans and as I get them into Power Point I'll post it on my website so you all can see what I'm doing. Dan Rhoades www.rhoadescameras.bizland.com - Original Message - From: Robert Mueller [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, October 25, 2001 2:14 AM Subject: Re: [Cameramakers] Rack and pinion template system Would it not be easier to mill the teeth (router) with a shaped cutter and just some device to advance the cutter by one tooth spacing after each row of cuts. Making cutters should be quite easy. The rack can have straight sided teeth and it is not hard to make an involute cutter for the gear. Metal workers have all the details worked out. Bob At 21:47 24.10.01 -0600, you wrote: I was wondering in anyone would be interested in a template/jig to be able to shape and cut a rack and pinion out of wood. I'm working with a engineer with a good CNC metal shop to build a jig system for cutting the pinion and rack by hand using files and chisels. I think African Blackwood, Cocobolo, Hard Maple or other hard stable woods would be great for gearing since there isn't a lot of pressure on the gear teeth. The design we are working is based on hardened steel runners in which you would place the piece of wood in between two jigs, clamp the wood tight, drill the center hole using a predrilled hole in the steel that would guide the bit straight, and then cut and file each tooth. The rack will be a similar design but won't need the center hole. Now, I'm going to build one for myself since I like having rack and pinion focusing on my cameras and a wood system is so much cooler than adding metal to the system. My friend (Kirk Kovel of Kovel Precision Machine in Colorado Springs) can build the system cheaper in production than one at a time so if others want this type of system we can all benefit from a cheaper price. He is also great since he knows that this is just a hobby and none of us are out to make money doing this so he charges a reasonable price. I have no idea at this time what the cost per unit would be since more units will bring down the price, but the price would be at cost. My current camera is using a 16 tooth system and is quite stable with no stress on the gear teeth. I think a 32 or even a 64 tooth system would be quite reasonable and workable but I want to see what any other interested parties would like. The other size requirements we need to work out amongst ourselves is the size of the pinion and the length of the rack. My current system has the pinion at a 2 diameter and the rack at 16 long and that seems to work well. Alright, let's see if anyone is interested and we'll work out the details and see if anyone has good ideas to make this system work. Dan Rhoades http://www.rhoadescameras.bizland.comwww.rhoadescameras.bizland.com ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Rack and pinion template system
One other thought; I do not do any high class woodwork but my father did. I can imagine using the cutters I just described to make teeth by hand in the good, old fashioned way I saw as my father made moldings. Bob ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Rack and pinion template system
You are right, and not quite so right! The trouble is that the correct rack for a lantern pinion is a cycloid but an involute rack has straight-sided teeth, and there are a lot to cut. Conversely, A lantern pinion might just be the way to get the strength in the pinion teeth. Bob At 15:53 25.10.01 -0400, you wrote: I have made clocks and wonder why the pinion gear when a lantern gear is so much easier to make. Jim Ketcheson Matt Mengel wrote: Hey all, I am a machinist, and I agree that a cutter for a router would be the easiest way to cut the teeth for the rack. ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Thin glass for a within-camera platen - thanks for help
How about just having a glass about a centimeter is front of the film. Then pressurize only the chamber between film and glass. The bellows is free of pressure and the volume is far smaller, yet dust on the glass will be far less obvious and the glass will not be touched so there will be no tendency to develop scratches. A spot will have to be pretty bad to show on the film unless you are working at rather small diaphragm openings. Continuous pumping is better than minimally practical and is used in some good commercial cameras (I suspect most working on precision projects in the larger formats.) It is awkward for normal photography, even in a studio, but I doubt if it is more than a minor problem if well thought out. Bob At 05:27 23.10.01 +, you wrote: I assume you do realize that pressure or vacuum alone isn't what is going to flatten the film. It is the pressure differential between the opposite sides of the film that will hold it in place. In other words, you will need to ensure that there is less pressure behind the film than in front of it. If you make things air tight and simply pressurize the chamber you would presumably have the same pressure behind the film as in front of it. That doesn't gain you anything. After all, if you do nothing the chamber is pressurized according to your local barometric pressure. I'm guessing you'd always want to have an air leak behind the film if you want to pressurize the film chamber. Yes, I understand all this and that's the reason why I'm using the rubber strips to seal just the area around the film opening in the the front (lens side) of the back instead of the entire back. While some degree of air will always leak out of the pressurized bellows, the amount that leaks out right now is larger than I'd like since it requires pumping air into the bellows continously in order to make my setup work. While this is minimally practical in a studio environment, it's totally impractical in the field. I know the bellows will need to be relieved of some pressure between shots in order to allow for focusing and movements but having to pump it up each time from empty is more work than I'm willing to undertake, especially with the small rubber bulb I'm hoping to use. Jeff Goggin Scottsdale, AZ ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Thin glass for a within-camera platen - thanks for help
At 05:27 23.10.01 +, you wrote: Why not just put a glass about a centimeter in front of the film. Dust on this glass will make a very diffuse shadow except possibly at very small diaphragm openings, so you are unlikely to notice it. Conversely, the volume to be pumped is smaller than when you pump the bellows and the notmal swings and tilts have no influence on the pressure, or vice versa. You also eliminate scratching of the glass with this scheme. Continuous pumping is fully practical in a stationary setting and is probably standard for the larger formats for repro work and various precision operations like photoetching, where exact flatness is needed and the film is rather large to support only at the edges, anyway. In the usual studio being connected to a pump could be awkward, but if the back design is good I suspect the extra trouble will be hardly disturbing. Bob Yes, I understand all this and that's the reason why I'm using the rubber strips to seal just the area around the film opening in the the front (lens side) of the back instead of the entire back. While some degree of air will always leak out of the pressurized bellows, the amount that leaks out right now is larger than I'd like since it requires pumping air into the bellows continously in order to make my setup work. While this is minimally practical in a studio environment, it's totally impractical in the field. I know the bellows will need to be relieved of some pressure between shots in order to allow for focusing and movements but having to pump it up each time from empty is more work than I'm willing to undertake, especially with the small rubber bulb I'm hoping to use. Jeff Goggin Scottsdale, AZ ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] ROTATING CAMERA PROJECT IDEAS
I insert some comments below; Bob At 10:07 22.10.01 -0400, you wrote: OK. Here it is. Is this what you are interested in? http://www.rit.edu/~andpph/text-conical-strip.html Sam Hello! I could use some input. I have an idea for a rotating 4x5 slit camera. The plan is to have the camera rotate 360 degrees, while exposing through a lens and slit a rotating 360 degree image around the center of a 4x5 sheet film. I can do the woodworking out of 1/4 oak. I did the calculations and will use a 40mm lens (from a 35mm camera). So here is where i can use some help: 1) Camera Rotation: I see that a steping motor with some type of controller (a bit expensive) A DC motor with a voltage controller (less Expensive) A spring motor like in some rotating cameras, but I have no idea how to get that to work # You can drive a stepping motor with a 2 - phase oscillator. If you can do the electronics, so much the better, but otherwise somebody might help you. There are designs in data books from semiconductor manufacturers, National Semiconductor, for example. You also will probably need a small power amplifier (stereo for the two channels.) Running the motor on a pair of sine waves 90 degrees out of phase should give rather smoother motion than running with the usual sharp pulses. If you can build it will be quite cheap. (I think you could do it for $10 or less with all new parts but not counting a PCB if decide to use one. It is not needed!!) And my favorite since it would be cheapest, a motorless camera ala the 35mm Lookaround camera. This is a hand holdable wooden 35mm camera with wings that are spun around and at some point the shutter/film transport is triggered??? 2) slit shutter: Since the image will be exposed around a circle (imagine a record player) I need to be able to open the slit shutter and close it at exactly 359 degrees, so I don't over expose. Alsi it would not be good to close the shutter before completing the rotation. ### Does it really do damage to have a little overlap? If you scan 380 degrees nobody will care! The shutter can close anywhere in the, say, 20 degrees overlap. The simplest idea I have, is a thin metal shutter, with a light spring. Some type of small electro magnet can be triggered to open, and than at a set point in the rotation released, closing the shutter by the spring. You can probably arrange some sort of cam to open the shutter when the camera rotates to touch the cam and then close the shutter when the camera reaches a similar mechanical device, like another cam. (It would work with a shutter having a Time setting with minimal trouble.) No electromagnets, nothing! If you like the electromagnetic shutter, there are some around. Some of the newer oscilloscope cameras had them but you must find the correct models. I could offer you such a thing but the one I have is a little big (it worked with a typical oscilloscope lens, which is usually about 75 mm focal length.) You can have it at my typical cost plus the postage but I think you can do as well at ebay because the post from here is not all that cheap. Still, if you want it, I am sure I can come up with one (with lens, if you want. 75 mm might be better on 8x10, or 4x10! Any ideas where I can scavenge such a magnet? i like to steal parts from disposable cameras, broken cameras, VCRs etc. ###You could rotate the shutter out of the way with a motor out of a dead camera or a CD player (or CD ROM) The motors in CDROM drives are quite small (the one for the drawer of the head motion. The motor for the CD rotation is unlikely to be useful.) I'll try and put up some drawings incase I havent explained the project clearly. Any advice would be appreciated. This is a real experimental camera. I think the effect ls like applying the Polar Coordinants filter in Photoshop. Thanks! Mac ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] re: crackpot medievalists or creative endeavors?
Yes! Absolutely correct. However, for a hemisphere you get 90 degrees coverage at the corners. It is already a bit of a wide angle; if I remember correctly, one usually defines a normal lens as one with focal length equal to the length of the diagonal. Here we have the focal length at 1/2 of the diagonal. Incidentally, I am not sure what focusing means with respect to a pinhole. Bob At 21:31 03.10.01 +, you wrote: If you were to use a wide-angle (i.e., short focus) lens, wouldn't you have to use much less than 1/2 a sphere in order to have the lens close enough to the film to focus? RKS From: [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: [EMAIL PROTECTED], [EMAIL PROTECTED] Subject: Re: [Cameramakers] re: crackpot medievalists or creative endeavors? Date: Wed, 3 Oct 2001 07:48:43 EDT In a message dated 10/3/01 6:07:34 AM, [EMAIL PROTECTED] writes: You might also consider a hemisphere; Bob -- This intrigues me. How would you do it? I am thinking of 8 X 10 with a wide angle lens. Marty ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers _ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Re: pinhole camera
Thank you, Barry. This is what I suspected (feared?) In fact, it is possible to buy metal foils in narrow widths and about =.0001 inch thick, but they will be rather expensive and I doubt if they will be appearing in hobby shops. However, if somebody really has a source of inexpensive material covering the range from 0.0001 to 0.0005, it would be wonderful. Unfortunately, except for 0.0005 (which I can get here, as a rough metric approximation), the only sources I know are specialists for scientific raw materials and the prices might be a turn-off. To be a little more concrete, I have a catalog in front of me, and there I find various metals (brass, stainless steel and many others) at about $75 to $100 for a piece 25 mm x 25mm (1 inch x 1 inch). This is for material 5 microns (0.0002 inch thick). At 12.5 microns thick the price drops by 30% or so. In selected, pure metals less than 0.0001 inch is possible; tantalum is offered at 1.5 microns and $150 for 25 mm x 25 mm. (Tantalum is a wonderful metal to work.) This thickness is just a few wavelengths of light (roughly 3 wavelengths for light in the middle of the visible spectrum) However, take Barry's advice, you hardly need such thin material for a pinhole. Furthermore, if you make the hole and then rub the finished product on a fine sharpening stone (India), and press correctly (try a finger over the hole) you can thin the foil locally, with the fastest thinning at the edge of the hole. You then have support by stronger, outer material and a thinner pinhole. Observe frequently with a microscope to know when you about to go too far! Incidentally, if you do go for the thinnest foils, you can make a lot of pinholes for your money so it may not be a bad investment. Just glue a 5 mm x 5 mm piece with the hole over a thicker foil with a larger (2 mm ?) hole. You would be getting 25 such holes for your $100.00 and nobody says you can't make still smaller chunks from your thin foil, getting the cost under $1.00 per hole. (I leave it to you to decide what to do with 100 pinholes in very thin foil.) Bob At 15:52 20.09.01 -0700, you wrote: I am a machinist. We use shim stock all day long. The thinnest shim we have been able to find is .0005 which is half a thousandth or five ten thousandths. We (Boeing) have not been able to find shim in .0001. But then, it woulkd be so weak it would tear when you drilled it. .001 works teriffic. I have used up to .002 with success. It is best if you drill a smaller hole with a needle then knock the burr off the other side with sandpaper, drill larger, deburr and go to final size. The thinned the shim material is at the edge of the hole the less diffraction problems you will have. Barry --- Robert Stoddard [EMAIL PROTECTED] wrote: Do you guys really mean one ten-thousandth of an inch shim stock? Can you possibly mean one thousandth of an inch (i.e., 0.001)? RKS From: Guillermo [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: [Cameramakers] Re: pinhole camera Date: Thu, 20 Sep 2001 16:18:49 -0400 RE: [Cameramakers] Re: pinhole camera - Original Message - From: J. Poutasse To: '[EMAIL PROTECTED]' Is it really possible to buy shim stock 0.0001 to 0.0005 at hobby shops in the USA? I've bought it in little packages with sheets of varying thicknesses at an auto parts store. It wasn't very expensive as I recall. One package will make lots of cameras. Jackie Jackie, I doubt you got any 0.0001 to 0.0005 in the package you bought. I believe that the thinnest one available is 0.0005. Bob, I will check if my supplier here in Canada has or is able to order 0.0005, if so and you are interested in that thickness, I wouldn't mind buying it and sending it to you. I will contact you off list. Guillermo ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers _ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers __ Terrorist Attacks on U.S. - How can you help? Donate cash, emergency relief information http://dailynews.yahoo.com/fc/US/Emergency_Information/ ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Re: pinhole camera
Is it really possible to buy shim stock 0.0001 to 0.0005 at hobby shops in the USA? Is there somebody who would please send me information on prices and maybe even offer to mail me some if I send the cost of postage and the goods. I see no reason why more is needed than putting it into an envelope between two sturdy pieces of cardboard. (I can't help wondering whether there might be one Zero too many!) Bob Mueller [EMAIL PROTECTED] ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] 14X17 film holder
If nobody else comes forward, I have a bunch of data, but they would best be faxed. If no better source appears, please let me know. Bob At 09:38 03.09.01 -0700, you wrote: Let's expand this just a tad. I'd like to put a table of standard film holder dimensions (4x5, 5x7, 8x10, etc.) on the cameramakers web page. Anyone have these handy? Any other tables of dimensions that we should have a common reference point for? - Wayde Take a look at; http://home.online.no/~gjon/lffaq.htm Ted _ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Pinhole Measurement
How about measuring the light transmission of the pinhole with a light meter? Shine a strong lamp on the pinhole at a known distance between the lamp and pinhole and pinhole and a screen. Measure the spot on the screen with a normal lightmeter of adequate sensitivity.Then calibrate by using a pinhole of a calibrated size, say 1 mm. I believe a machinists #60 drill makes a hole quite near 1 mm. Of course, the distances are kept the same in both measurements. Don't forget the light intensity goes as diameter squared, as does the aperture scale of the light meter. Instead of a screen, you could just put the lightmeter behind the pinhole (maybe with or maybe without an incident light option). This would offer more sensitivity but you must be a little careful to correctly hit the sensor and you should keep in mind that if the sensor is a photoresistor it may give quite different readings if the same amount of light falls as a concentrated spot on the sensor as compared to falling fairly well uniformly over the sensor. The incident light option gets around this and a photo diode based meter is unlikely to exhibit the problem. A suitable source can reduce this problem greatly. Bob PS How about avoiding the whole issue by making the hole the correct size by construction. If you push a tapered needle into whatever is receiving the hole and you know the needle diameter at the largest diameter of the needle which entered the hole, don't you more or less know the pinhole diameter. You can measure a needle with a workshop micrometer. You could also puch the needle into an existing hole until it stops and measure in the same way. I once made a gauge for small holes working this way, following a design known for decades if not centuries! Dr. Robert Mueller Institut für Festkörperforschung, FZ-Juelich D-52425 Juelich, Germany phone: + 49 2461 61 4550 FAX: + 49 2461 61 2610 email: [EMAIL PROTECTED] ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] aerial camera shutter assy..
To anyone interested: if you have several of these I would love to buy one from you (just the shutter) and will gladly post for all whatever I can determine about using one. I feel quite sure they are not too difficult to apply, though getting the most from one may require you to build some electronics. My own motivation is a lens (or two) needing a fair-sized shutter. I have smaller ones from oscilloscope cameras (electronically driven) which work but are not sufficient for the lens(es). Bob At 20:40 29.07.01 +, you wrote: Has anyone figured out how to make these shutters work (besides the original manuf. and customer)? RKS From: Gene Johnson [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: [Cameramakers] aerial camera shutter assy.. Date: Sun, 29 Jul 2001 09:48:42 -0700 I have one of these, I have not been able to figure it out either. It came out of a KS-87b lens I bought. Really neat piece of machinery though. Very strong springs, electric motor, solenoids, and two sets of scissors like shutter blades. Gene Johnson erie patsellis wrote: ran across this while browsing today- http://www.surplusshed.com/list.cfm?Category=Miscellaneous third or fourth item down, Ill be ordering one to play with, will make a good winter project and for $25, what the hell erie ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers _ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers Dr. Robert Mueller Institut für Festkörperforschung, FZ-Juelich D-52425 Juelich, Germany phone: + 49 2461 61 4550 FAX: + 49 2461 61 2610 email: [EMAIL PROTECTED] ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Condensers for enlargers available.
To all enlarger builders: I just saw 6 inch diameter, 10 inch focal length condensers offered at Surplus Shed. This diameter might be a bit small for absolutely full coverage of 4x5 negatives but it comes close to doing the job (I don't have the actual image size of a 4x5 at hand so I cannot verify. Sorry!). Bob Dr. Robert Mueller Institut für Festkörperforschung, FZ-Juelich D-52425 Juelich, Germany phone: + 49 2461 61 4550 FAX: + 49 2461 61 2610 email: [EMAIL PROTECTED] ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Replacement Foam
I am sorry to be coming back to this so late but I just returned from a trip abroad and only found the postings on this topic yesterday. Fist of all, I will let out some venom for the makers of cameras who put this polyurethane foam in their products. This stuff is predestined to turn to paste, damaging the camera in the process. Considering the price of a quality camera and the fact that a good camera SHOULD last for many decades, the manufacturers ought to be forced to repair the damage without cost to the owner of the camera. This foam is like a time bomb in the machine. It makes no difference what I think, a lot of you have cameras with this paste in them and need a fix. As has been suggested, felt is something to think about, but there are a couple other materials offering a lot of hope. One is soft leather, like chamois. Generally this will be a little thin if used as a single layer and multiple layers will not be as soft as PU foam; however, consider forming a tube with the seam of the tube glued down, away from the side getting slapped by whatever is falling on the tube. You might even put a bit of something in the tube (see below!). Unfortunately leather also does not offer an infinite lifetime and in time it will get brittle and fail, but the mess will be easier to cleam up than what you have when the PU foam reaches the end of its life. There is a better longterm outlook for silicone foam (Sounds somewhat like silly cone, and not to be confused with silicon, which many persons do, because silicon is a hard element which is brittle and quite useless for this task.) Look for this foam at your DIY shop. I have bought it as a seal for doors and windows. The most convenient form is a long strip about 50 mm wide to be used at the bottom of the door. This is 2 to 3 mm thick and is fastened to the door to keep air from leaking under the door. Its flexibility lets it follow the variation of the floor as the door moves over the floor. There are other shapes offered. Some seal the door around the edge when it is closed. Others are intended for sealing windows. In fact, in a few cases, these other shapes may be better than the flat strip. My experience is that samples of this foam are in perfect condition after 20 years. The foam has a smooth outer surface with pores inside. This can be useful in applications in which something slides over the foam. The foam would last longer when the pores are not exposed. You can shave the smooth surface away in cases where it does more harm than good. The real problem might be in finding this material. I suggest anyone who locates a source should tell us the brand and source of supply. (I bought mine decades ago and treat it like a treasure. Furthermore, I buy in a market to which most of you have little access, and I have little access to yours so I do not know what you can buy. Sorry!) Another problem is that I have only brown and white. Black would be nice if it can be found. Silicone will absorb some solutions and might let in dye, but will such treatment shorten the life? I have no idea, but brown is probably not all that bad for absorbing light, and better a tight brown seal than a leaky black one or one with a short future. Good luck. Dr. Robert Mueller Institut für Festkörperforschung, FZ-Juelich D-52425 Juelich, Germany phone: + 49 2461 61 4550 FAX: + 49 2461 61 2610 email: [EMAIL PROTECTED] ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Re: Bellows making (Urethane!)
I do not know whether I have access to anything similar to the "PL" Roof and Flashing Sealant but I doubt if I would use it even if I could buy it unless I received a pretty secure guarantee of a long lifetime. Urethane foam is one of the worst materials which have ever been introduced into cameras. This is the stuff which changes into mud after cameras exceed a certain age. Removing and replacing this junk is a terrible task and I am sure many otherwise fine cameras have landed in the scrap heap on account of the costs it causes to have a repairman spend much time cleaning up the camera before replacing the foam. A fantastic initial bond followed by self destruction after a decade or so is no solution in a case where only a moderate strength bond is needed, though for at least my remaining life on earth (estimated at 20 to 30 years!) Perhaps the problem has been solved in modern urethane, but I have never heard anybody admit there has ever been a problem so I don't expect any assurance it will never happen again. Until you have that assurance, consider the sinking feeling when you find your work reduced to a paste impregnated bag by decay of the cement. Bob Dr. Robert Mueller Institut fr Festkrperforschung, FZ-Juelich D-52425 Juelich, Germany phone: + 49 2461 61 4550 FAX: + 49 2461 61 2610 email: [EMAIL PROTECTED] ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Re: Ground Glass
One possible cause of uneven etching might be insufficient cleaning. Grime on the glass surface can cause parts of the glass to begin etching only later because the etching compound had to work through local regions of "grease-like" "resist"! Persons making high quality optics give a lot of attention to cleaning. Try scrubbing well and maybe even give the glass a soak in a moderate strength lye solution (which in itself can attack glass, but which also destroys grease.) The other proposal to take seriously is Sandy King's idea that the etching mixture was not well mixed. When cleaning, after the last rinse notice whether the water wets the glass with a nice uniform and thin layer. It not, clean some more! It is probably best to begin etching after shaking off as much rinse water as possible but before the glass dries, especially if distilled water is not being used. Bob Dr. Robert Mueller Institut fr Festkrperforschung, FZ-Juelich D-52425 Juelich, Germany phone: + 49 2461 61 4550 FAX: + 49 2461 61 2610 email: [EMAIL PROTECTED] ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Re: bellows
I am no expert at this but have tried a couple experiments which were not too bad. Things with which you might want to experiment: 1) IBM punch cards are a nice material for stiffers, if you can find a source. There are similar materials around if all the local supplies of punch cards have dried up. 2) I made one bellows with magnetic cards as stiffeners. These are coated with a magnetic material which is optically dense and the base material is rugged Mylar(TM). These will be harder to find than punch cards but were used in the late 1969s for storing data on small computers. The size is similar to that of a punch card. 3) Contact cement is an appealing glue but I consider handling it horrible if a large area thin coat is wanted. Most methods will produce lots of "strings". You can thin the cement to reduce this problem but there are spray can versions of this adhesive. Much of the trouble never occurs. However, consider well how you will align any layers of material put together with this stuff; any mistake could mean a great loss of quality or a total loss of the bellows. Once the two layers are in contact it is very difficult to separate them without destroying something. 4) Silicone as used to seal leaks in your bathroom and elsewhere in the house is an interesting and versatile adhesive. It does not stick as strongly as many other adhesives, but a bellows should not be a highly loaded item. I have made fabric light-tight with it by using black silicone as supplied, or what I like better because I have more control, you can add lampblack to it. Try your local print shop for a sample of black printers ink. This is lampblack in an oil base. The oil should harden in air, eventually!A few percent of this in the silicone renders it pretty opaque already in fairly thin layers. However, silicone is really far too viscous as supplied. You can thin it with suitable solvents. I use something similar to mineral spirits or white spirit or "spezial Benzin", as it is known here. Try what you have on a sample before undertaking the real job. Quite a lot of the solvent is needed. I have never had the nerve to attempt spraying but do clean a spray gun immediately after use if you try it. Once cured about the only way to remove the stuff is mechanically. Brushing or rolling this into the stretched fabric will make it opaque yet the end product is quite flexible. The best fabric will be one which is already as optically dense as possible (see all those other contributions!) Work in a well ventilated area; all that solvent must evaporate. It is well to mention why the bother makes any sense. Silicone is pretty stable against deterioration; much better than normal rubber. Time might show a bellows produced with this has a very long lifetime (I admit I am guessing!) I have fabric for dark room shades but I expect it to become brittle with time and have seem items which suffered exactly that fate. These were shades which you could rip up as if they were made of tissue paper and a bellows which was in terrible condition. Auto tires do not have infinite lifetime also when the car is not driven (sunlight makes the situation worse for tires but is less of a threat for a bellows!); the rubber becomes hard and porous. Silicone is likely to resist these processes. Furthermore, the silicone itself is almost the bellows material, with the fabric serving as reinforcement and stiffener. It also defines the thickness. Silicone cures somewhat slowly, though it quickly builds a skin on the surface. The slow cure gives more working time than would contact cement. Oh, yes. Please do not make up a siliconized cloth and then use it long afterwards to make a bellows. Not much securely sticks to this stuff after it is well-cured. Try to laminate the bellows soon after coating the cloth, or better, impregnate the cloth after the bellows layers are bonded. More than a day long wait is asking for trouble. Bob Dr. Robert Mueller Institut fr Festkrperforschung, FZ-Juelich D-52425 Juelich, Germany phone: + 49 2461 61 4550 FAX: + 49 2461 61 2610 email: [EMAIL PROTECTED] ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Re: Blackening Brass Rails
Perhaps some of you might be interested in experimenting with "misuse" of some commonly available "finishes". It is hard to get two component paints or anything approaching other commercial paints in terms of durability. However, it is not too hard to use epoxy intended for gluing or casting to provide a quite tough and adherent finish. One which works may not be available to you under the same name but it is called "UHU Plus" here. Today it is no longer so marked but older packages were identified as being the same as Araldite. I assume it still is like Araldite and it looks the same, but a change in composition is possible. You almost surely can buy products using the same composition. I believe these can be thinned by using mineral spirits or "white spirit". Do the thinning after mixing or else be careful about the ratio of thinner to epoxy components so when you blend them the desired ratio of catalyst to resin is maintained. This will make a clear finish which you can apply on top of chemically blacked brass to preserve it (or on bright brass!) An epoxy which you will not so easily buy is 2850FT from Emerson Cuming (I am sorry if I failed to get the spelling exactly correct.), but this costs us about $25.00 per kilogram and works as a fair, black paint. Here you really should be careful with mixing and I strongly recommend thinning only after mixing of the two components (and stir the resin before adding catalyst.) This can certainly be thinned with acetone and I believe I also had success with mineral spirits as well because I painted a large object on which I would have been afraid to use acetone (acetone is pretty effective at destoyong many paints and a part of what I was coating was already painted.). The final mixture is not easy to apply but you can get a dilution adequate to give decent results. I have never tried spraying though it would be interesting, BUT USE A SPRAY BOOTH AND/OR OTHER LUNG PROTECTION IF YOU TRY IT.) After the solvent has evaporated you can bake either of these epoxies which increases the bond strength to the brass or whatever, and helps the products to flow, giving a smoother result. Thr finishes will normally be glossy so they may not be ideal inside a camera but they should be excellent outside, for parts where the glossy, black look is desired. Both epoxies are tough, but the black 2850 FT contains fairly hard particles which ought to increase resistance to abrasion compared to most unfilled finishes. Please experiment to find the best solvent (others will almost certainly also work) and amount of thinning. Good luck! Bob Dr. Robert Mueller Institut fr Festkrperforschung, FZ-Juelich D-52425 Juelich, Germany phone: + 49 2461 61 4550 FAX: + 49 2461 61 2610 email: [EMAIL PROTECTED] ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
[Cameramakers] Scanners as digital film backs
I just saw some of the messages about attempts to use a scanner to convert images at the back of a camera or the output of an enlarger into digital form. This should work and I consider doing it as well, but there are problems which some messages hint at. The source of the problem is that a page scanner is much like a tiny camera in which only one line of the image is actually processed at a time (then this line is moved over the paper to be digitized.) Try to imagine the following (or do it!). Stand in front of a slide projector set up to show a 4 foot wide image on a screen. Look into the lens. All you see is a small circle of light of great intensity (perhaps 2 inches in diameter). You do not see much resembling the image being projected even when your head is about where the screen is. As one person commented, a piece of ground glass would solve this, either at the place of the screen in my "model", or on top of the flat bed of the scanner if you placed it at the back of a large format camera. If you put in the ground glass you will be able to get some kind of an image but you can expect a "hot spot" at the center and massive light losses everywhere else. Not a great solution. The problem is simple; the light needed to produce parts of the image 2 feet to your left or right is not headed toward your eye: There is nothing reaching the eye to produce any effect. You can use the light much more efficiently in this configuration (with the scanner at the back of a 4x5 inch camera, for example) if you insert a so-called "field lens". This would serve to bend the light rays which are headed in the wrong direction back into the tiny scanner camera. There is only one problem; such a field lens would have to be highly corrected and would be both unwieldly and expensive.(Imagine the price of a lens with the quality of a camera lens but with a diameter equal to that of the diagonal of a 4x5 film. You could get the diameter down SOME by scanning the field lens, too.) In fact, this is the wrong way to do it. I suggest giving up on large format as such and use smaller optics of high quality to throw the image directly onto the CCD ( which probably still should scan to get the "other dimension"). Probably either medium format or 35 mm optics projecting the image directly onto a CCD would give good service. This "mini-LF" camera could have all the swings and tilts you wanted, though operating it would not be trivial at first because it would be so small. However, with a well-thought out constuction this thing could probably compete well with a decent LF camera in performance and spare optics would be far cheaper. Using a 1200 dpi scanner as a basis, there would be nearly 10,000 pixels (1200 dpi x 8 inches paper width) across an image. Compare this to a 4 inch wide image at 50 line pairs per millimeter (100 mm x 100 lines=10,000 points per line where 50 line pairs is crudely equal to 100 lines and 100 mm is just 4 inches in SI units) You find everything is just about right for saying the two are similar capability, assuming the large format lens is up to 50 line pairs per mm; resolution that good is called "excellent" over the tiny frame of a 35 mm photo and Schneider quotes the MTF for its lenses at 20 cycles per mm. The CCD s typically have about the correct dimension for such a construction. What I have not yet determined is how to know what the size of the CCD in a given model of scanner is without opening the scanner, so I can buy the correct scanner at the start. In truth, the sizes do not vary all that much! Dr. Robert Mueller Institut fr Festkrperforschung, FZ-Juelich D-52425 Juelich, Germany phone: + 49 2461 61 4550 FAX: + 49 2461 61 2610 email: [EMAIL PROTECTED] ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
