Re: [pinhole-discussion] couple of pictures
- Original Message - From: "G.Penate" To: Sent: Wednesday, February 28, 2001 6:55 PM > > Paper or film won't bend around a tight sphere, only a cylinder. Some months ago, I tried to build a small spherical film plane camera around a tennis -ball basis. I had cut a tennis ball in 2 halves, took one of these and built a "pinhole lensboard" which I adapted on the half ball. I did many tries to fix adequately photo paper (single weight) and film in this spherical back but I never succeeded to get a regular surface : it is too difficult to bend equally such a surface in all directions : I got scratches, wrinkles, tears, everything except a plain surface, and though my patience goes far (as most pinholers), I finally gave the ball tennis to ... my grey parrot to play with. Jean Jean Daubas, auteur-photographe Rue de Bourg-Sec25440 LIESLEFrance tél. 03 81 57 50 13 / 06 81 53 12 89 jean.dau...@freesbee.fr
Re: [pinhole-discussion] couple of pictures
- Original Message - From: "Richard M. Koolish" > A spherical film plane would eliminate one of the cosine squared factors in > illumination, but leave the other one. That's right, it eliminates the one COS^2 factor to account for "inverse square law", also eliminates the one COSINE factor to account for the pinhole covering more area due to the light falling obliquely. The fall-off is then reduced to just one COSINE factor, the one that accounts for the aparent smaller pinhole area as we move off axis. > I think that in a cylindrical camera like an oatmeal box, the illumination > is even more uniform because the edges of the negative get closer to the > pinhole, at least in one dimension. Good observation. For the original poster of the question that type of camera is not an answer, tho, as he is more concern with "sharpness" rather than fall-off. > Paper or film won't bend around a tight sphere, only a cylinder. One > photographic telescope design that astronomers use is called a Schmidt > camera, ...stuff deleted I like to know this type of details! Thx for the info and link. Guillermo
Re: [pinhole-discussion] couple of pictures
> A spherical shaped film plane would be ideal to maximize the edge > "sharpness", I guess I should say: to minimize edge softness (instead), as > well as minimizing the fall-off. Practically, though, cylindrical is the > shape most suitable to accomodate either film or paper. I believe that in > one of the 2 editions of Renner Pinholo Photography books there is a picture > of a guy that made a spherical film plate dug in the ground and B&W paper > placed to conform the shape of the hole. > > Guillermo A spherical film plane would eliminate one of the cosine squared factors in illumination, but leave the other one. The pinhole still has a smaller effective area as you move off axis. Even so, this produces more even illumination than a flat camera, at the expense of introducing distortion. I think that in a cylindrical camera like an oatmeal box, the illumination is even more uniform because the edges of the negative get closer to the pinhole, at least in one dimension. Paper or film won't bend around a tight sphere, only a cylinder. One photographic telescope design that astronomers use is called a Schmidt camera, and it has a curved focal plane. In order to get sharp star images from edge to edge, the film or glass plate is bent in a shallow convex sphere and held by clamps. The 48" diameter camera at Mt. Palomar uses 14" square plates 1mm thick. I'm told that plates are tested first before being put in the telescope as some of them break when bent. To see a picture of this telescope with famous astronomer Edwin Hubble, see: http://opostaff.stsci.edu/~levay/presres/ehubble/jpeg/10_12-17.jpg
Re: [pinhole-discussion] couple of pictures
I think I've seen this, but can't remember where. Pam "G.Penate" wrote: > ... there is a picture > of a guy that made a spherical film plate dug in the ground and B&W paper > placed to conform the shape of the hole. > > Guillermo > > ___ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??? > unsubscribe or change your account at > http://www.p at ???/discussion/ -- Pamela G. Niedermayer Pinehill Softworks Inc. 600 W. 28th St., Suite 103 Austin, TX 78705 512-236-1677 http://www.pinehill.com
Re: [pinhole-discussion] couple of pictures
Think of cutting out a format sized segment from a sphere, just have to place supports so the film/paper is forced to lay on the sphere's inside. However, the wheel of cheese approach is good, too, as is a horizontal cylinder. Pam William Erickson wrote: > > I've daydreamed a lot about shpeircal film planes but I haven't figured out > how to do it. You can do one curved in one dimension, though. The radius of > the curve is the 'focal length" of the aperture. It makes the camera look > like half a wheel of cheese. In the ones I've made like this there is > minimal distortion at the edges and its equally sharp all the way around. > - Original Message - > From: Pam Niedermayer > To: > Sent: Tuesday, February 27, 2001 2:51 PM > Subject: Re: [pinhole-discussion] couple of pictures > > > How spherical would the film plane have to be to get to sharp edges? > > Let's say I'm building an 8x10 pinhole camera (which I am), and wanted > > to build a special curved film holder. Should the spere be around the > > distance from pinhole to film center, the pinhole being the center of > > the sphere? > > > > Pam > > > > William Erickson wrote: > > > > > > I'd guess that edge softness is a product of the fact that the plane of > > > optimal sharpness is a hemisphere centered aroiund the hole, and the > film > > > plane is flat, transecting the optimal image best at the center, or if > > > rounded, not rounded at the same radius. > > > - Original Message - > > > From: Simon Cygielski > > > To: > > > Sent: Tuesday, February 27, 2001 3:56 AM > > > Subject: [pinhole-discussion] couple of pictures > > > > > > > Hi all, > > > > I've uploaded a couple of my first efforts with my 6x17 cm panoramic > > > > pinhole camera. They're up at > > > > > > > > http://www.p at ???/discussion/upload/images/path1.jpg and > > > > http://www.p at ???/discussion/upload/images/phones2.jpg > > > > > > > > I built the camera out of a Holga using bookboard to expand it to its > > > > present size. "Focal" length is 7.5 cm. Any comments would be > > > > appreciated. > > > > I also have a question: is the loss of sharpness on the far edges > > > > inevitable, or can it be corrected somehow? perhaps thinner stock? > This > > > > hole was made (fairly carefully) out of a Coke can and sized according > > > > to some pinhole formula (though I forget which one), so it should be > > > > somewhere in the ballpark size-wise. > > > > Thanks, > > > > Simon > > > > > > > > > > > > ___ > > > > Pinhole-Discussion mailing list > > > > Pinhole-Discussion@p at ??? > > > > unsubscribe or change your account at > > > > http://www.p at ???/discussion/ > > > > > > > > > > ___ > > > Pinhole-Discussion mailing list > > > Pinhole-Discussion@p at ??? > > > unsubscribe or change your account at > > > http://www.p at ???/discussion/ > > > > -- > > Pamela G. Niedermayer > > Pinehill Softworks Inc. > > 600 W. 28th St., Suite 103 > > Austin, TX 78705 > > 512-236-1677 > > http://www.pinehill.com > > > > ___ > > Pinhole-Discussion mailing list > > Pinhole-Discussion@p at ??? > > unsubscribe or change your account at > > http://www.p at ???/discussion/ > > > > ___ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??? > unsubscribe or change your account at > http://www.p at ???/discussion/ -- Pamela G. Niedermayer Pinehill Softworks Inc. 600 W. 28th St., Suite 103 Austin, TX 78705 512-236-1677 http://www.pinehill.com
Re: [pinhole-discussion] couple of pictures
I've daydreamed a lot about shpeircal film planes but I haven't figured out how to do it. You can do one curved in one dimension, though. The radius of the curve is the 'focal length" of the aperture. It makes the camera look like half a wheel of cheese. In the ones I've made like this there is minimal distortion at the edges and its equally sharp all the way around. - Original Message - From: Pam Niedermayer To: Sent: Tuesday, February 27, 2001 2:51 PM Subject: Re: [pinhole-discussion] couple of pictures > How spherical would the film plane have to be to get to sharp edges? > Let's say I'm building an 8x10 pinhole camera (which I am), and wanted > to build a special curved film holder. Should the spere be around the > distance from pinhole to film center, the pinhole being the center of > the sphere? > > Pam > > William Erickson wrote: > > > > I'd guess that edge softness is a product of the fact that the plane of > > optimal sharpness is a hemisphere centered aroiund the hole, and the film > > plane is flat, transecting the optimal image best at the center, or if > > rounded, not rounded at the same radius. > > - Original Message - > > From: Simon Cygielski > > To: > > Sent: Tuesday, February 27, 2001 3:56 AM > > Subject: [pinhole-discussion] couple of pictures > > > > > Hi all, > > > I've uploaded a couple of my first efforts with my 6x17 cm panoramic > > > pinhole camera. They're up at > > > > > > http://www.p at ???/discussion/upload/images/path1.jpg and > > > http://www.p at ???/discussion/upload/images/phones2.jpg > > > > > > I built the camera out of a Holga using bookboard to expand it to its > > > present size. "Focal" length is 7.5 cm. Any comments would be > > > appreciated. > > > I also have a question: is the loss of sharpness on the far edges > > > inevitable, or can it be corrected somehow? perhaps thinner stock? This > > > hole was made (fairly carefully) out of a Coke can and sized according > > > to some pinhole formula (though I forget which one), so it should be > > > somewhere in the ballpark size-wise. > > > Thanks, > > > Simon > > > > > > > > > ___ > > > Pinhole-Discussion mailing list > > > Pinhole-Discussion@p at ??? > > > unsubscribe or change your account at > > > http://www.p at ???/discussion/ > > > > > > > ___ > > Pinhole-Discussion mailing list > > Pinhole-Discussion@p at ??? > > unsubscribe or change your account at > > http://www.p at ???/discussion/ > > -- > Pamela G. Niedermayer > Pinehill Softworks Inc. > 600 W. 28th St., Suite 103 > Austin, TX 78705 > 512-236-1677 > http://www.pinehill.com > > ___ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??? > unsubscribe or change your account at > http://www.p at ???/discussion/ >
Re: [pinhole-discussion] couple of pictures
- Original Message - From: "Pam Niedermayer" > This means the spherically shaped film > holder would have to be different for each focal length. Ouch. :) A spherical shaped film plane would be ideal to maximize the edge "sharpness", I guess I should say: to minimize edge softness (instead), as well as minimizing the fall-off. Practically, though, cylindrical is the shape most suitable to accomodate either film or paper. I believe that in one of the 2 editions of Renner Pinholo Photography books there is a picture of a guy that made a spherical film plate dug in the ground and B&W paper placed to conform the shape of the hole. Guillermo
Re: [pinhole-discussion] couple of pictures
Thanks, George, that's what I was trying to confirm. I should have said something more like the distance from pinhole to film plane would be the radius of the sphere. This means the spherically shaped film holder would have to be different for each focal length. Ouch. :) Pam George L Smyth wrote: > > --- Pam Niedermayer wrote: > > How spherical would the film plane have to be to get to sharp edges? > > Let's say I'm building an 8x10 pinhole camera (which I am), and wanted > > to build a special curved film holder. Should the spere be around the > > distance from pinhole to film center, the pinhole being the center of > > the sphere? > > Imagine tying a string on the pinhole, then swiping it along the film plane. > That is the curvature you want to use if you want to distort the film plane so > that there is a constant "focal length." > > Cheers - > > george -- Pamela G. Niedermayer Pinehill Softworks Inc. 600 W. 28th St., Suite 103 Austin, TX 78705 512-236-1677 http://www.pinehill.com
Re: [pinhole-discussion] couple of pictures
--- Pam Niedermayer wrote: > How spherical would the film plane have to be to get to sharp edges? > Let's say I'm building an 8x10 pinhole camera (which I am), and wanted > to build a special curved film holder. Should the spere be around the > distance from pinhole to film center, the pinhole being the center of > the sphere? Imagine tying a string on the pinhole, then swiping it along the film plane. That is the curvature you want to use if you want to distort the film plane so that there is a constant "focal length." Cheers - george = Handmade Photographic Images http://members.home.net/hmpi/ __ Do You Yahoo!? Get email at your own domain with Yahoo! Mail. http://personal.mail.yahoo.com/
Re: [pinhole-discussion] couple of pictures
How spherical would the film plane have to be to get to sharp edges? Let's say I'm building an 8x10 pinhole camera (which I am), and wanted to build a special curved film holder. Should the spere be around the distance from pinhole to film center, the pinhole being the center of the sphere? Pam William Erickson wrote: > > I'd guess that edge softness is a product of the fact that the plane of > optimal sharpness is a hemisphere centered aroiund the hole, and the film > plane is flat, transecting the optimal image best at the center, or if > rounded, not rounded at the same radius. > - Original Message - > From: Simon Cygielski > To: > Sent: Tuesday, February 27, 2001 3:56 AM > Subject: [pinhole-discussion] couple of pictures > > > Hi all, > > I've uploaded a couple of my first efforts with my 6x17 cm panoramic > > pinhole camera. They're up at > > > > http://www.p at ???/discussion/upload/images/path1.jpg and > > http://www.p at ???/discussion/upload/images/phones2.jpg > > > > I built the camera out of a Holga using bookboard to expand it to its > > present size. "Focal" length is 7.5 cm. Any comments would be > > appreciated. > > I also have a question: is the loss of sharpness on the far edges > > inevitable, or can it be corrected somehow? perhaps thinner stock? This > > hole was made (fairly carefully) out of a Coke can and sized according > > to some pinhole formula (though I forget which one), so it should be > > somewhere in the ballpark size-wise. > > Thanks, > > Simon > > > > > > ___ > > Pinhole-Discussion mailing list > > Pinhole-Discussion@p at ??? > > unsubscribe or change your account at > > http://www.p at ???/discussion/ > > > > ___ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??? > unsubscribe or change your account at > http://www.p at ???/discussion/ -- Pamela G. Niedermayer Pinehill Softworks Inc. 600 W. 28th St., Suite 103 Austin, TX 78705 512-236-1677 http://www.pinehill.com
Re: [pinhole-discussion] couple of pictures
I'd guess that edge softness is a product of the fact that the plane of optimal sharpness is a hemisphere centered aroiund the hole, and the film plane is flat, transecting the optimal image best at the center, or if rounded, not rounded at the same radius. - Original Message - From: Simon Cygielski To: Sent: Tuesday, February 27, 2001 3:56 AM Subject: [pinhole-discussion] couple of pictures > Hi all, > I've uploaded a couple of my first efforts with my 6x17 cm panoramic > pinhole camera. They're up at > > http://www.p at ???/discussion/upload/images/path1.jpg and > http://www.p at ???/discussion/upload/images/phones2.jpg > > I built the camera out of a Holga using bookboard to expand it to its > present size. "Focal" length is 7.5 cm. Any comments would be > appreciated. > I also have a question: is the loss of sharpness on the far edges > inevitable, or can it be corrected somehow? perhaps thinner stock? This > hole was made (fairly carefully) out of a Coke can and sized according > to some pinhole formula (though I forget which one), so it should be > somewhere in the ballpark size-wise. > Thanks, > Simon > > > ___ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??? > unsubscribe or change your account at > http://www.p at ???/discussion/ >
Re: [pinhole-discussion] couple of pictures
- Original Message - From: "Simon Cygielski" > I've uploaded a couple of my first efforts with my 6x17 cm panoramic > pinhole camera. They're up at > http://www.p at ???/discussion/upload/images/path1.jpg and > http://www.p at ???/discussion/upload/images/phones2.jpg Wow, I like them. That camera/format shows lots of potential, try some images of very close subjects/objects. > I built the camera out of a Holga using bookboard to expand it to its > present size. "Focal" length is 7.5 cm. Any comments would be > appreciated. There is nothing like either making your own camera or modifying a camera to make it a pinhole one. Congratulations on your industriousness. Having said that, I wish I had the expendable money to get a Finney!! :-( > I also have a question: is the loss of sharpness on the far edges > inevitable, or can it be corrected somehow? perhaps thinner stock? This > hole was made (fairly carefully) out of a Coke can and sized according > to some pinhole formula (though I forget which one), so it should be > somewhere in the ballpark size-wise. Most people would be asking about the fall off at the edges, which in most cases I really like, it adds favorable pinhole quality to many subjects. Here is an idea that may or may not be helpful in answering your questions, it is based on the loss of sharpness due to diffraction: Geometrically speaking, the edges of the film see an oval shaped pinhole, fact that is made worst if the stock is very thick compared to the diameter of the pinhole. At the farthest corner of the film, in your case, the pinhole would appear to be just about 64% as it actually is. Assuming your pinhole is about 0.0125" in diameter (optimum for 75mm focal length according to D= 0.0073 * SQRT(focal length) , the farthest edges see an oval 0.0125" tall and 0.008" wide. The "vertical" sharpness is not affected "as much", the film still sees a pinhole as big as the original. The "horizontal" sharpness" is affected diffraction wise as the film now "sees" a smaller hole (0.008") that is optimum for 30mm instead of 118mm (focal length) at the farthest corner of your film. If you make the pinhole bigger to fully compensate for its apparent "ovalness" when seen from the edges of the film, you will be affecting the sharpness at the center of the film. Sharpness is affected at the edges not only because the film sees no longer a round aperture, but also because the "focal length" or distance pinhole-film at the edges of the film is much bigger than at the center of the film, requiring a bigger pinhole. By making the film plane to conform to a cylindrical shape with the pinhole in the center, the edges will still see an oval instead of a round aperture, but at least the focal length will be the same, helping to decrease diffraction and hopefully improving edge sharpness satisfactorily. One thing for sure will be improved substantially and that is fall off at the edges. In resume, for very wide angle of view cameras with flat film planes: use a thinner stock, make sure the pinhole is clean of burrs and make your pinhole a bit bigger than the optimum for the center of the film plane. Guillermo
Re: [pinhole-discussion] couple of pictures
Very cool. As to edge sharpness, is the film supported all the way across by rails of some sort? Is it possible that in building the extension the ends went off plane? Or (can you tell I'm just guessing here? ) maybe the rails need to be curved just a bit to accommodate the hole. Pam Simon Cygielski wrote: > > Hi all, > I've uploaded a couple of my first efforts with my 6x17 cm panoramic > pinhole camera. They're up at > > http://www.p at ???/discussion/upload/images/path1.jpg and > http://www.p at ???/discussion/upload/images/phones2.jpg > > I built the camera out of a Holga using bookboard to expand it to its > present size. "Focal" length is 7.5 cm. Any comments would be > appreciated. > I also have a question: is the loss of sharpness on the far edges > inevitable, or can it be corrected somehow? perhaps thinner stock? This > hole was made (fairly carefully) out of a Coke can and sized according > to some pinhole formula (though I forget which one), so it should be > somewhere in the ballpark size-wise. > Thanks, > Simon -- Pamela G. Niedermayer Pinehill Softworks Inc. 600 W. 28th St., Suite 103 Austin, TX 78705 512-236-1677 http://www.pinehill.com
Re: [pinhole-discussion] couple of pictures
--- Simon Cygielski wrote: > I also have a question: is the loss of sharpness on the far edges > inevitable, or can it be corrected somehow? perhaps thinner stock? This > hole was made (fairly carefully) out of a Coke can I would definitely say that thinner stock would be appropriate. I use pie pans, which work fairly well. Another possibility might be out of your hands. Because of the wide nature of the camera, the focal length between the middle and the ends may be significant enough to be noticeable. Cheers - george = Handmade Photographic Images http://members.home.net/hmpi/ __ Do You Yahoo!? Get email at your own domain with Yahoo! Mail. http://personal.mail.yahoo.com/
Re: [pinhole-discussion] couple of pictures
on 2/27/01 4:56 AM, Simon Cygielski at si...@wbj.pl wrote: > Hi all, > I've uploaded a couple of my first efforts with my 6x17 cm panoramic > pinhole camera. They're up at > > http://www.p at ???/discussion/upload/images/path1.jpg and > http://www.p at ???/discussion/upload/images/phones2.jpg Simon, I'm really impressed. I would like to see a picture of the camera. Is is a curved back? James
[pinhole-discussion] couple of pictures
Hi all, I've uploaded a couple of my first efforts with my 6x17 cm panoramic pinhole camera. They're up at http://www.p at ???/discussion/upload/images/path1.jpg and http://www.p at ???/discussion/upload/images/phones2.jpg I built the camera out of a Holga using bookboard to expand it to its present size. "Focal" length is 7.5 cm. Any comments would be appreciated. I also have a question: is the loss of sharpness on the far edges inevitable, or can it be corrected somehow? perhaps thinner stock? This hole was made (fairly carefully) out of a Coke can and sized according to some pinhole formula (though I forget which one), so it should be somewhere in the ballpark size-wise. Thanks, Simon
