[Cameramakers] (no subject)
I know this sounds dumb but what is a condenser lens exactly. I know several sources for a variety of different kind of lenses, maybe I could help. Gene Johnson [EMAIL PROTECTED] wrote: Hello! I have a printmaker 35mm enlarger. I'd like to upgrade it to cover 6x6 Holga negs. There is a kit from Beseler for $100-150 which includes 2 4" condenser lenses which go in the current head. I'd rather not spend this much. Anyone have a surplus source where I can buy condenser lenses? I could build the little tray to hold the lenses. Any other ideas in converting an enlarger like this to cover a larger format, Thanks Mac ___ ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] using CCD's for cameras
On Wed, 3 Jan 2001, ken watson wrote: The packages are hermetically sealed. It would be difficult removing the glass, the color filters will most likely change once exposed to humidity and other contaminants we are talking about 5 micron sq. photodiodes so dust may also be a problem. OK, but since these things are used in real devices the flare issue can probably be dealt with. How do the scanner manufacturers solve the flare problem that got us to this point? The obvious solution that comes to mind for me would be to minimize internal reflections in the camera housing. Even traditional film isn't flat black and causes some flare. Perhaps the digital sensor could be mounted at a slight angle so that surface reflections would be directed at a light absorbing surface? As long as you know that angle, and possible the transfer function of the optical path, you could probably correct the resulting image abberations programatically or even design the optics to compensate. This is a lot of spoofing to get the device to do what you may want. The problem centers around most flat bed scanners actually scan the underside lip first where they get the information for white balance AND light level before they read the glass. If the sensor encounters out of range I have no idea what they do. I think there are serveral issues here. First of all, people have already made cameras out of old scanners, so we know that it CAN be done. Secondly, this group has a fair number of tinkerers, engineers, and machinists so even hacking into the low level electronics, although perhaps difficult, can be part of the "fun". Finally, you have to consider that one may not need to go any lower level than this to simply get a scanner to do what you want. I do not know of any one that has engineering kits. A search on the web found a kit from TI http://www.ti.com/sc/docs/psheets/abstract/apps/socu005.htm. Not to mention that there is a pretty big market for computer imaging systems, not just digital cameras and scanners, that sells imaging solutions. For example: http://www.sbig.com/sbwhtmls/online.htm http://www.mars-cam.com/frame/boardccd/boardccd.html http://www.ti.com/sc/docs/msp/snapshot.htm The other issue is that the CCD itself can be damaged by only 5KV of static discharge. This is considered extremely low so any handling of the device or assembly is hazardous to its health. The electrostatic discharge issue is nothing particularly new. The chips in your PC can be damaged by 5 kV discharges. However, I agree that this is on the low end of the scale. If you get a noticeable static spark from your fingers it can easily have a potential of 100 kV or more. There are however ways to mitigate the problem. I think the key thing is that this is a pretty experimental crowd. I'd like to foster a sense of innovation here and see what people can come up with. - Wayde ([EMAIL PROTECTED]) ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] 4 condenser lenses for enlarger?
Here's a couple thoughts on the condenser lenses thing. First: condenser lenses take light that is scattered and moving in all directions and get it all moving in (more or less) the same direction. Thin increases the intensity of the light moving through the negative, shortens printing times and thus improves the efficiency of the enlarger. The downside of this is that any dust, lint or other no-see-ums on the negative will also print with greater clarity and sharpness as well. Condenser lenses also focus the infrared part of the spectrum unless used with a large sheet of heat adsorbing glass (an added expense). Condenser lens enlargers are sometimes so efficient they can sometimes burn a hole right through your negative or at least cause it to "pop" and render your image on the easel out-of-focus (the popping if of course more likely with medium format negatives for two reasons--thinner film base stocks and more distance between supporting edges of the carriers!). You can fix this by using a carrier with top and bottom glass plates to hold your negative flat--at the expense of introducing four more surfaces that you need to dust before printing. Second: a suggestion, don't use condensers at all!! If all you are doing is experimenting with medium format, replace the condensers with a couple of sheets of ground glass and print using diffused light. The dust problem goes away but you've got to keep you're negative exposure and development to a minimum because the light source isn't very efficient. But if you fall in love (with diffused light) you are in luck. You can probably find a new or used cold light head (fluorescent tube type) from Aristo to fit your enlarger or a color head (which uses diffused quartz halogen light and "mixing boxes" sized for the negative type) you are using for between $100 and $200. darkroommike - Original Message - From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Wednesday, January 03, 2001 11:44 PM Subject: Re: [Cameramakers] 4" condenser lenses for enlarger? In a message dated 1/3/01 8:44:31 PM Central Standard Time, [EMAIL PROTECTED] writes: I know this sounds dumb but what is a condenser lens exactly. I know several sources for a variety of different kind of lenses, maybe I could help. Gene Johnson [EMAIL PROTECTED] wrote: Hello! I have a printmaker 35mm enlarger. I'd like to upgrade it to cover 6x6 Holga negs. There is a kit from Beseler for $100-150 which includes 2 4" condenser lenses which go in the current head. I'd rather not spend this much. Anyone have a surplus source where I can buy condenser lenses? I could build the little tray to hold the lenses. Any other ideas in converting an enlarger like this to cover a larger format, Thanks Mac ___ A condenser lens is actually a pair of matched Convex lenses, (Convex/plano?) placed 'back to back' in such a way that the curved surfaces face each other in the middle, and the flats are on the outside. (The convex lenses are basiclly just magnifying lenses, but flat on one side) The idea behind the condenser lense is to allign the light rays into a more or less straight path. A four inch diameter condenser is just about the smallest one should try to use for 6x6. I know of no source of such lenses outside of the photography industry. One might try Edmund Scientific... They sell a lot of lenses. I have a set of condensers such as one would use for 6x6, but I'm keeping them, sorry! (I also have a set for 8x10, lets talk!) Someone sugested replacing the Printmaker, via eBay. I agree. This could well be the best way to go. Even if one could get the 6x6 setup working with the printmaker, you must realize that the extra weight of the bigger glass would tend to make it unstable, and top heavy. Find an old Bessler 23c II. VERY rugged, very stable, parts still available. Best of luck: [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] optical switchs.
On Thu, 4 Jan 2001, Michel Dusariez wrote: Thanks for all repys about optical switchs. Gene Johnson sent me some scanned schematics for some optically switched relays. I've made this scan available on the web at http://rmp.opusis.com/cameramakers/relays.jpg. - Wayde ([EMAIL PROTECTED]) ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Linear CCD's for cameras
I looked at a local spy shop a while ago. They have several "spy pinhole cameras" that produced unbelievably good pictures for their resolution. They work with a VCR so I suppose a USB frame grabber or something would work to capture pictures. The surprising thing was the sensitivity it had for low light levels. The one I was looking at was going for $75.00. It was a module needing an external power supply - another $12.00 or so for one of the transformer 6V jobs. I am thinking of using something like this as a previewer for a long pinhole camera in order to aim it. Larry -Original Message- From: Gregg Kemp [EMAIL PROTECTED] To: '[EMAIL PROTECTED]' [EMAIL PROTECTED] Date: Thursday, January 04, 2001 11:11 AM Subject: RE: [Cameramakers] Linear CCD's for cameras I modified a Barbie digital camera about a year and a half ago to use a pinhole. I was curious to see the effect of direct rays of light on the CCD. The biggest problem I had was in getting an image at all. The optimal pinhole size was too small to allow enough light through to ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] using CCD's for cameras
- Original Message - From: "Brian Reynolds" [EMAIL PROTECTED] Please unsubscribe me - thank you in advance. Do it yourself, follow the link at the bottom of this message. ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
