Re: [pinhole-discussion] 6x22 pinhole camera coverage?!
- Original Message - From: Tom Miller tomwmil...@attbi.com To: pinhole-discussion@p at ??? I've read a rule of thumb that at 30 degrees the fall of is one stop and that at 45 degrees it is two stops. It seems like there is a possibly handy formula in there. Tom, Forgot answering this other question. That rule of thumb is good, but to be precise, 1 stop is at 32.76 degrees. A formula to find the angle at which a specific fall off is found would be: If S = stops of fall off Angle = ArcCosine [(1 / 2^S)^0.25] or for better clarity: http://members.rogers.com/gpenate/angle.gif for 1 stops it would be: Angle = ArcCosine [(1 / 2^1)^0.25] Angle = ArcCosine [(1 / 2)^0.25] Angle = ArcCosine [0.5^0.25] Angle = ArcCosine [0.840896] Angle = 32.76 degrees for 2 stops it would be: Angle = ArcCosine [(1 / 2^2)^0.25] Angle = ArcCosine [(1 / 4)^0.25] Angle = ArcCosine [0.25^0.25] Angle = ArcCosine [0.70710678] Angle = 45 degrees Guillermo
Re: [pinhole-discussion] 6x22 pinhole camera coverage?!
- Original Message - From: Tom Miller tomwmil...@attbi.com To: pinhole-discussion@p at ??? This put two questions in head. First, would a concave film plane reduce the fall off ratio? Optimally, the film plane could be curved in a way that makes the entire film plane equally distant from the pinhole. I looked at the 6x22 camera's photo on the silver-whatever web site and it looked like it could possibly have a curved film plane, although I couldn't tell if would be hemisperical like the Mottweiler Pinoramic. Disclaimer, none of the these is needed to be known to practice extreme wide angle pinholing, but if somebody ask this questions, I am happy to oblige. Tom, The camera in question looks very thin, so I am pretty sure it is a flat film plane camera. Yes, a concave film plane would reduce the fall off ratio. Using a film plane conforming to a half circle and positioning the pinhole at the center of the circle would reduce the fall off by a very substantial amount. In math terms, it is reduced from being cosine^4, to just cosine of the off axis angle. There is a catch, tho, in the case of this camera (6x22), the focal length has to be increased to allow the width of the film to fits in the semi-circle. Second, what is the formula that you used to calculate the fall off? I'm curious because I've been doing a fair bit of extreme wide-angle stuff lately and it doesn't seem like the light falls off as much as one would think. I think that we expect pinhole images to have severe fall off, therefore the actual fall off we get doesn't look to be that severe (am I making any sense?), it is almost magical and even seemingly defying physic laws! but I am pretty sure is just subjective perception. It is a flat film plane camera with a 1:3.7 ratio. I've read a rule of thumb that at 30 degrees the fall of is one stop and that at 45 degrees it is two stops. It seems like there is a possibly handy formula in there. There is a law in optics called Cosine^4 law, all lenses, including glass lenses are subjected to it. It says that the intensity of light at a off axis point will be reduced by a factor equal to cosine to the power of four of the off axis angle. In your camera with ratio 1:3.7 (I'll assume this ratio is focal length : width of format), which BTW has very similar ratio than the one we've been discussing 60mm/22cm, the sides of the film are 61.6 degrees off axis, hence, as per Cosine^4 law, the intensity of light at the sides will be just: Cosine(61.6) x Cosine(61.6) x Cosine(61.6) x Cosine(61.6) = 0.051174 In other words, if at the center we have an intensity of 100 units (whatever units), at the sides, it'll be just 5.1174 units. To find how many stops that correspond to, we just multiply 0.05117 by 2 as many times as needed to reach 1 , the number of times you multiply by 2 is the number of stops of fall off. A faster and precise way is using this formula: Stops of fall off = 3.322 x Log ( 1 / 0.051174 ) = 4.29 stops If W = width of camera in mm and F = focal length of the camera in mm, a single formula to find the fall off at the sides of the film would be: http://members.rogers.com/gpenate/stopsW.gif If instead we want to find the fall off at the corners of the film, when H = height of film, the formula becomes: http://members.rogers.com/gpenate/stopsWH.gif Correction welcomed. Guillermo
Re: [pinhole-discussion] 6x22 pinhole camera coverage?!
If the camera has a curved film plane, there will be no fall off. Mike Vande Bunt Andrew Amundsen wrote: The camera is said to have a 60mm focal length. Does anyone have experience with images made that wide, nearly 8.5 inches, from such a focal lenth (at f/360) on 120 film? Are the edges even useful at that extreme? I guess what I'm getting at is this camera a gimmick? Will the user most likey have to crop only the center portion of the neg. for a usable image and not really get the full 22cm effect? What do you think? Thanks, Andrew -- From: Scott Sellers scottsell...@mindspring.com Andrew Amundsen a...@tcinternet.net wrote (snip): My inquiry is regarding how an image would look from such a long neg.? The stated aperture size is f/360. Would the edges suffer from extreme distortion? I'm surprised that the coverage would even fill that length of 22cm!? They share no images produced with said camera so I have doubts, with my limited understanding of pinhole imagery, to how good the detail would be at the extremes? Anyone care to enlighten us with some expertise? The main factor when considering coverage is focal length. To get an idea of how a particular FL will cover various formats, you could make say an 8x10 a camera of the same focal length, shoot some images, then mask off the negative size you are considering, be it 6x6, 6x9, 6x22, 4x5, 5x7, etc. cheers, Scott ___ Post to the list as PLAIN TEXT only - no HTML Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
Re: [pinhole-discussion] 6x22 pinhole camera coverage?!
First they copied Zernike Au designs and now they are making this camera. I wont be buying it. It must be hard to get 120 film to span across the 22cm back. I will wait and see if Zernike Au makes a new camera. Much better to buy an original than a copy.
RE: [pinhole-discussion] 6x22 pinhole camera coverage?!
Guillermo wrote: The aperture is irrelevant, the only thing that matters is the ratio width of format to focal length (corner-corner distance to focal length if one wants to be exact). The ratio of that camera is 3.6 which in theory will have a 4.25 stops fall off at the sides with respect to the center, this kind of fall off is horrendous for glass photography, but for pinhole images, in practice, it doesn't look as big as one may think, IMO. As an example, this image http://members.rogers.com/gpenate/greek.jpg is a portion of a larger image made with a camera with ratio 3 width/focal length, that should give a fall off of 3.4 stops at the top and bottom of the image with respect to the center, and if you ask me, it doesn't look that big of a fall off. This put two questions in head. First, would a concave film plane reduce the fall off ratio? Optimally, the film plane could be curved in a way that makes the entire film plane equally distant from the pinhole. I looked at the 6x22 camera's photo on the silver-whatever web site and it looked like it could possibly have a curved film plane, although I couldn't tell if would be hemisperical like the Mottweiler Pinoramic. Second, what is the formula that you used to calculate the fall off? I'm curious because I've been doing a fair bit of extreme wide-angle stuff lately and it doesn't seem like the light falls off as much as one would think. It is a flat film plane camera with a 1:3.7 ratio. I've read a rule of thumb that at 30 degrees the fall of is one stop and that at 45 degrees it is two stops. It seems like there is a possibly handy formula in there. Thanks, Tom
Re: [pinhole-discussion] 6x22 pinhole camera coverage?!
My inquiry is regarding how an image would look from such a long neg.? The stated aperture size is f/360. Would the edges suffer from extreme distortion? I'm surprised that the coverage would even fill that length of 22cm!? The aperture is irrelevant, the only thing that matters is the ratio width of format to focal length (corner-corner distance to focal length if one wants to be exact). The ratio of that camera is 3.6 which in theory will have a 4.25 stops fall off at the sides with respect to the center, this kind of fall off is horrendous for glass photography, but for pinhole images, in practice, it doesn't look as big as one may think, IMO. As an example, this image http://members.rogers.com/gpenate/greek.jpg is a portion of a larger image made with a camera with ratio 3 width/focal length, that should give a fall off of 3.4 stops at the top and bottom of the image with respect to the center, and if you ask me, it doesn't look that big of a fall off. They share no images produced with said camera so I have doubts, with my limited understanding of pinhole imagery, to how good the detail would be at the extremes? Again, their camera has a 3.6 ratio, my example image has a 3 ratio, that tells me that if the conditions are favorable: clean pinhole, thin material, good lighting of the extremes of the scene, etc., the detail should be acceptableand if it not, I really like the heavy fall off to the edges effect, too. Having said all that, I wouldn't buy or use a camera from that company, reasons are obvious. Guillermo
[pinhole-discussion] 6x22 pinhole camera coverage: gimmick?
Andrew, I'm with Andy on this one. Just give it a try. You bet you'll get falloff. When I shoot 4x5 using 50mm of focal length, the fall-off is a good 2-3 stops from center to corner. Not only that, but with a focal length that barely covers the film (or even doesn't), you can get very interesting distortion of near objects. Even when I've gone radical, and used a mere 18mm of focal length for 4x5, and ended up with a 1-1/2 inch circular image on the sheet plus the usual falloff, it's still been interesting and provocative. I find the results so worthwhile that when I designed my 7x17 camera, I deliberately chose a focal length of six inches so it barely will cover the film corner to corner. That one still isn't up and running yet, so I can't vouch for the results. I'll tell you, though, the edges are going to look just fine, no matter what they look like. Some of the photographers who participated in this year's Pinhole Exchange showed just how interesting an image can become if we embrace this edge problem that's making you hesitate. I'm thinking of Ingo Guenther's image of a church and (one of my absolute favorites) David Balihar's simple image of fruit rotting in a field. Each of them achieved a stunning effect by working with the falloff. In fact, I think that one reason Ingo's is so strong, is because even without falloff, the image is overwhelmed by negative space. The edge falloff actually contributes to the eye's impression that the brightly lit church is having to fend off darkness and shadows. Another good example is Michael Vaughan's, which was shot from inside a 35mm film canister. How much focal length does one of THOSE give you?! All of them terrific examples of what you can achieve with a focal length that's, ahem, too short. Mike Healy - Original Message - From: andy schmitt aschm...@warwick.net To: pinhole-discussion@p at ??? Sent: Saturday, March 15, 2003 1:44 PM Subject: RE: [pinhole-discussion] 6x22 pinhole camera coverage?! try it. I have a 4x5 that does about a 30mm focal length. The fall off is a really neat effect. You can crop it if you don't like it for the particular image. andy -Original Message- From: pinhole-discussion-admin@p at ??? [mailto:pinhole-discussion-admin@p at ???]On Behalf Of Andrew Amundsen Sent: Saturday, March 15, 2003 2:48 PM To: pinhole-discussion@p at ??? Subject: Re: [pinhole-discussion] 6x22 pinhole camera coverage?! The camera is said to have a 60mm focal length. Does anyone have experience with images made that wide, nearly 8.5 inches, from such a focal lenth (at f/360) on 120 film? Are the edges even useful at that extreme? I guess what I'm getting at is this camera a gimmick? Will the user most likey have to crop only the center portion of the neg. for a usable image and not really get the full 22cm effect? What do you think? Thanks, Andrew -- From: Scott Sellers scottsell...@mindspring.com Andrew Amundsen a...@tcinternet.net wrote (snip): My inquiry is regarding how an image would look from such a long neg.? The stated aperture size is f/360. Would the edges suffer from extreme distortion? I'm surprised that the coverage would even fill that length of 22cm!? They share no images produced with said camera so I have doubts, with my limited understanding of pinhole imagery, to how good the detail would be at the extremes? Anyone care to enlighten us with some expertise? The main factor when considering coverage is focal length. To get an idea of how a particular FL will cover various formats, you could make say an 8x10 a camera of the same focal length, shoot some images, then mask off the negative size you are considering, be it 6x6, 6x9, 6x22, 4x5, 5x7, etc. cheers, Scott ___ Post to the list as PLAIN TEXT only - no HTML Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/ ___ Post to the list as PLAIN TEXT only - no HTML Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
RE: [pinhole-discussion] 6x22 pinhole camera coverage?!
try it. I have a 4x5 that does about a 30mm focal length. The fall off is a really neat effect. You can crop it if you don't like it for the particular image. andy -Original Message- From: pinhole-discussion-admin@p at ??? [mailto:pinhole-discussion-admin@p at ???]On Behalf Of Andrew Amundsen Sent: Saturday, March 15, 2003 2:48 PM To: pinhole-discussion@p at ??? Subject: Re: [pinhole-discussion] 6x22 pinhole camera coverage?! The camera is said to have a 60mm focal length. Does anyone have experience with images made that wide, nearly 8.5 inches, from such a focal lenth (at f/360) on 120 film? Are the edges even useful at that extreme? I guess what I'm getting at is this camera a gimmick? Will the user most likey have to crop only the center portion of the neg. for a usable image and not really get the full 22cm effect? What do you think? Thanks, Andrew -- From: Scott Sellers scottsell...@mindspring.com Andrew Amundsen a...@tcinternet.net wrote (snip): My inquiry is regarding how an image would look from such a long neg.? The stated aperture size is f/360. Would the edges suffer from extreme distortion? I'm surprised that the coverage would even fill that length of 22cm!? They share no images produced with said camera so I have doubts, with my limited understanding of pinhole imagery, to how good the detail would be at the extremes? Anyone care to enlighten us with some expertise? The main factor when considering coverage is focal length. To get an idea of how a particular FL will cover various formats, you could make say an 8x10 a camera of the same focal length, shoot some images, then mask off the negative size you are considering, be it 6x6, 6x9, 6x22, 4x5, 5x7, etc. cheers, Scott ___ Post to the list as PLAIN TEXT only - no HTML Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
Re: [pinhole-discussion] 6x22 pinhole camera coverage?!
The camera is said to have a 60mm focal length. Does anyone have experience with images made that wide, nearly 8.5 inches, from such a focal lenth (at f/360) on 120 film? Are the edges even useful at that extreme? I guess what I'm getting at is this camera a gimmick? Will the user most likey have to crop only the center portion of the neg. for a usable image and not really get the full 22cm effect? What do you think? Thanks, Andrew -- From: Scott Sellers scottsell...@mindspring.com Andrew Amundsen a...@tcinternet.net wrote (snip): My inquiry is regarding how an image would look from such a long neg.? The stated aperture size is f/360. Would the edges suffer from extreme distortion? I'm surprised that the coverage would even fill that length of 22cm!? They share no images produced with said camera so I have doubts, with my limited understanding of pinhole imagery, to how good the detail would be at the extremes? Anyone care to enlighten us with some expertise? The main factor when considering coverage is focal length. To get an idea of how a particular FL will cover various formats, you could make say an 8x10 a camera of the same focal length, shoot some images, then mask off the negative size you are considering, be it 6x6, 6x9, 6x22, 4x5, 5x7, etc. cheers, Scott
Re: [pinhole-discussion] 6x22 pinhole camera coverage?!
On 0, Andrew Amundsen a...@tcinternet.net wrote: [...] My inquiry is regarding how an image would look from such a long neg.? The stated aperture size is f/360. Would the edges suffer from extreme distortion? I'm surprised that the coverage would even fill that length of 22cm!? They share no images produced with said camera so I have doubts, with my limited understanding of pinhole imagery, to how good the detail would be at the extremes? Anyone care to enlighten us with some expertise? The main factor when considering coverage is focal length. To get an idea of how a particular FL will cover various formats, you could make say an 8x10 a camera of the same focal length, shoot some images, then mask off the negative size you are considering, be it 6x6, 6x9, 6x22, 4x5, 5x7, etc. cheers, Scott -- Scott Sellers| scottsell...@mindspring.com |
[pinhole-discussion] 6x22 pinhole camera coverage?!
(I apologize in advance to Zernike Au for bringing up the product of an English company, which I understand may have infringed on copyrights to the Zero Image's beautiful, original hand made wooden 120 series of pinhole cameras.) In the latest 'Amateur Photographer' magazine(UK) 8 March 2003, there is a small anouncement of a new 'Silver vista' pinhole camera (pg.5) which produces a 6x22cm negative, 3 images per 120 roll! My inquiry is regarding how an image would look from such a long neg.? The stated aperture size is f/360. Would the edges suffer from extreme distortion? I'm surprised that the coverage would even fill that length of 22cm!? They share no images produced with said camera so I have doubts, with my limited understanding of pinhole imagery, to how good the detail would be at the extremes? Anyone care to enlighten us with some expertise? Thanks for the time, Andrew
