S2PP Spring 2002 Pinhole Print Swap was Re: [pinhole-discussion] New Year's 2002 Swap
Hi all, Thanks to Rosanne for her info about New Year 2002 swap Forum ! ... And now do not forget that there is a S2PP Spring 2002 Pinhole print swap which may interest you : Hi you, happy Pinholer from somewhere in the world ! Following the success of the previous pinhole printswaps organized between members of this list, we are preparing a new one for next spring ! Maybe you wish to participate in the next pinhole print swap ? If so, there's nothing easier ! For now, please, just make me know ! We have some time ahead but the sooner, the better, since if we are numerous, we shall have to share in different groups with a moderator for each group. Today, we have already 21 people registered At the present time, no guidelines have been fixed yet; this will be done together later when we have a clear view of how many we are... We just need to know who is interested... I suggest that we do not bother the whole discussion-list with our printswap stuff. Please e-mail me at the following e-mail address (different from my e-mail address for the list) jean.dau...@freesbee.fr and please use the precise following suggested subject line : Subject : S2PP (it makes me earn a lot of time when sorting my received e-mails !) Hoping you will register soon (pinhole printswaps are a great experience), Cheers from France Jean --- Jean Daubas, auteur-photographe 16 rue de Bourg-Sec25440 LIESLEFrance tél. 03 81 57 50 13 / 06 81 53 12 89 jean.dau...@freesbee.fr - Original Message - From: ethereal art ethereal...@mindspring.com To: pinhole-discussion@p at ??? Sent: Wednesday, November 14, 2001 11:03 AM Subject: [pinhole-discussion] New Year's 2002 Swap rob wrote: this one? http://www.rahji.com/noindex/pinholexmas.php3 btw, it's not a xmas swap.. i just didn't change the url since i didn't want people who got it early on to get confused.) If you want to find out more about this, go to the pinhole vision forum at http://www.???/forum/index.php and click on Christmas Card Swap which is now New Year's 2002 Swap. Rosanne ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
Re: [pinhole-discussion] zone plate question
- Original Message - From: Richard M. Koolish kool...@bbn.com I'm not sure I would describe the workings of a zone plate this way. It doesn't matter where in the zone plate (or pinhole) the light passes through. It doesn't bend at one place and not in another. The way you think about a zone plate or pinhole is that every clear point acts like a spherical wave is generated there. Then from any point in the image plane, you add up all the contributions to the intensity at that position from all the individual contributing points of the zone plate or pinhole. Some waves will be in phase and reinforce each other, and some waves will be out of phase and destructively interfere. In the simple case of a pinhole, you discover, that a point source of light in a subject does not generate a true point of light at the film or even a simple disk, as if a beam of light came through. Instead, you get the clasic diffraction pattern of a point, i.e. a central disk (the Airy disk) surrounded by diffraction rings. Note that every aperture produces diffraction. Even the most perfect lens can't focus a point source into an image point. Normally you don't see this because the diffraction pattern is so small. An f/10 lens produces an Airy disk of only .0134 mm for green light. On the other hand, if you place a very small pinhole, say 50 microns (.05 mm) 100 mm away from the film and shine a red laser pointer at it, you will get a diffraction disk of about 3 mm in diameter. The zone plate has a lot of chromatic aberration. That is, it can't focus different colors of light at the same place. That's what causes the characteristic glow around bright objects in a zone plate photograph. One color may get focussed sharply and the others will get spread out into disks of various sizes around the sharp point. I can't speak to the issue of how much this changes with the number of rings in the zone plate since I haven't done any research on this. It would be an interesting and fairly easy experiment to try. Dick Koolish (kool...@bbn.com) ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
Re: [pinhole-discussion] zone plate question
Kate, I don't think I mentioned distortion in my post. A faster ZP has more clear rings, but that causes no distortion, the ZP camera still is free of linear distortion (at least). The increased number of clear rings increase the ratio noise/signal, tho. Noise is the light that reaches the film without having suffered diffraction, therefore do not contribute to the sharpness of the image, this is the light mostly responsible for the characteristic glow of a ZP image. Signal is the light that grazes the edges of the rings, suffer diffraction and is focused on the film plane, this light is the one resposible for the sharpness of the image. Guillermo I'm not sure I would describe the workings of a zone plate this way. It doesn't matter where in the zone plate (or pinhole) the light passes through. It doesn't bend at one place and not in another. The way you think about a zone plate or pinhole is that every clear point acts like a spherical wave is generated there. Then from any point in the image plane, you add up all the contributions to the intensity at that position from all the individual contributing points of the zone plate or pinhole. Some waves will be in phase and reinforce each other, and some waves will be out of phase and destructively interfere. In the simple case of a pinhole, you discover, that a point source of light in a subject does not generate a true point of light at the film or even a simple disk, as if a beam of light came through. Instead, you get the clasic diffraction pattern of a point, i.e. a central disk (the Airy disk) surrounded by diffraction rings. Note that every aperture produces diffraction. Even the most perfect lens can't focus a point source into an image point. Normally you don't see this because the diffraction pattern is so small. An f/10 lens produces an Airy disk of only .0134 mm for green light. On the other hand, if you place a very small pinhole, say 50 microns (.05 mm) 100 mm away from the film and shine a red laser pointer at it, you will get a diffraction disk of about 3 mm in diameter. The zone plate has a lot of chromatic aberration. That is, it can't focus different colors of light at the same place. That's what causes the characteristic glow around bright objects in a zone plate photograph. One color may get focussed sharply and the others will get spread out into disks of various sizes around the sharp point. I can't speak to the issue of how much this changes with the number of rings in the zone plate since I haven't done any research on this. It would be an interesting and fairly easy experiment to try. Dick Koolish (kool...@bbn.com)
Re: [pinhole-discussion] Re: Attachments (was: new zero 4x5)
No problem, James. This happens every so often on the list and it's always a good occasion to remind everyone about not posting attachments. Cheers, Guy jamesromeo wrote: on 11/14/01 8:05 PM, Guy Glorieux at guy.glori...@sympatico.ca wrote: I sent the photo to show a print done with the new zero not my work. I did not know the thing on attachments the photo comes up with the note you do not have to call it up. I am sorry for this error. James Thanks James, Very nice picture, indeed. I'd like to see more, but just a quick reminder not to post attachments on the list. You're best seen if you use the upload gallery of the Pinhole Visions site. Check the Discussion area at http://www.???/discussion/ then click on the upload gallery and it will take you there! Best wishes for more pictures with the Zero 4x5 and your 6x12 rollfilm holder. ...-:)) Guy jamesromeo wrote: on 11/14/01 5:05 PM, jamesromeo at jamesro...@mac.com wrote: taken with the new 4x5 zero 25mm pinhole with horseman 6x12 roll film holderI got about 2 weeks ago only 10 dayes from order nice little camera James ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/ ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
Re: [pinhole-discussion] zone plate question
- Original Message - From: Kate Hudec hu...@rcn.com I was interested in Guillermo's recent post about the relationship between number of rings and zone plate image sharpness. I have a converted Lubitel with 75mm focal length. If I wanted a camera with MORE distortion (which I understand from Guillermo's post would also be a faster camera), would I need a camera with a longer or shorter focal length? Thanks in advance. Kate, I don't think I mentioned distortion in my post. A faster ZP has more clear rings, but that causes no distortion, the ZP camera still is free of linear distortion (at least). The increased number of clear rings increase the ratio noise/signal, tho. Noise is the light that reaches the film without having suffered diffraction, therefore do not contribute to the sharpness of the image, this is the light mostly responsible for the characteristic glow of a ZP image. Signal is the light that grazes the edges of the rings, suffer diffraction and is focused on the film plane, this light is the one resposible for the sharpness of the image. As far as getting distortion using longer or shorter focal length: Very wide angles of view are considered distorting because of the radically altered perspective compared to what we are used to see with our own eyes. If this is the kind of distortion you refer to, then, with a 6x6 film format Lubitel, you would need to have (IMO) the lens (pinhole or ZP) as least as close as 30mm from the film plane (closer would be better). I too have a modified Lubitel and I believe that even carving the front of the camera and recessing the lens, it'd be impossible to install the lens 30mm or less from the film plane w/o having vignetting caused by the viewing lens. If you want to sacrifice the composing help the viewing lens afford, then I think it may be doable but it'd easier if you get a cheaper 6x6 folder camera remove the bellows and modify it as pinhole/ZP. Something like this one I made: ftp://penate:athx2...@members.home.com/penate/cameras/12.jpg or this ftp://penate:athx2...@members.home.com/penate/cameras/6x6.jpg Hope it answers your questions. Guillermo
