[pinhole-discussion] RE:BB Gun Pinhole
Way to go Joe! I couldn't get a decent image out of mine. Maybe it was poor shooting... either that, or the tinfoil really wasn't the best idea. I'm going to retry this tomorrow, if it stops raining (no complaints, though!). Post a pic of the camera itself, I'd like to see how you put it together. John Moore --- On Mon 03/17, Joe Rollins jroll...@starband.net wrote: From: Joe Rollins [mailto: jroll...@starband.net] To: pinhole-discussion@p at ??? List-Post: pinhole-discussion@pinhole.com Date: Mon, 17 Mar 2003 16:24:10 -0600 Subject: [pinhole-discussion] RE:BB Gun Pinhole There is nothing a Southern Boy enjoys as much as beer sex, except guns. My son did not think it the least bit wierd when I asked to borrow his pellet gun to make a pinhole. It was raining when this was done, so I have my camera and gun loaded for the first sunny day, and expect better results. I only captured a shot with the entrance pinhole. I love this idea, and plan to explore other 'caliber' of shots. Click on this link to see the resulting picture. http://jrollins.mystarband.net/pinhole%20'shot'.htm Focal Length-9.25 Pinhole Punch-.177 caliber wadcutter pellet traveling @ 875 ft/sec F Stop-52 Ilford Photo Paper Joe ___ No banners. No pop-ups. No kidding. Introducing My Way - http://www.myway.com
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] WWPD image 'hit counts'?
On 16 Mar 2003 at 0:04, Tom Miller wrote: Probably more important is the egalitarian nature of the WPPD exhibit. It is a place where all are equal. I'd be concerned that any counters attached to an image might give an impression that the number of winners on the site is less than the total number of participants. Agreed. Chris Ellinger Ann Arbor, MI
RE: [pinhole-discussion] WWPD image 'hit counts'?
Hi Andrew, Thanks for making this suggestion for the WPPD site. It has not been brought up before. I've posted your message to the Pinhole Visions Forum on Worldwide Pinhole Photography Day topics. It is at: http://www.???/forum/. The forum is a great place to discuss suggestions, plans and anything related to the Big Tiny Aperture event on April 27. I'll post my thoughts there, too. I'm not a web programmer, but I think generally the counters are attached to what, for lack of a better term, I'll call statically defined pages. I'm pretty sure (and our webmaster, Gregg Kemp, will correct me if I'm wrong) that the WPPD gallery pages are all dynamically generated. The thumbnail pages are generated based on the query criteria entered, like country, city, artist name, group, etc. I believe the individual image pages are also dymanically generated. This might make it difficult to attach a counter to an individual image. Probably more important is the egalitarian nature of the WPPD exhibit. It is a place where all are equal. I'd be concerned that any counters attached to an image might give an impression that the number of winners on the site is less than the total number of participants. I'm getting excited about April 27, too. My daughter (age 6) and I built identical tin cameras. We used refrigerator magnet stock for shutters. We decorated the shutters with colored markers so we could tell our cameras apart. Somehow she was able to fit the entire Wizard of Oz movie onto a 1.5 by 2 inch magnet! Tom Miller -Original Message- From: pinhole-discussion-admin@p at ??? [mailto:pinhole-discussion-admin@p at ???]On Behalf Of Andrew Amundsen Sent: Saturday, March 15, 2003 9:44 AM To: Pinhole Forum Subject: [pinhole-discussion] WWPD image 'hit counts'? For the organizers of the next WWPD #3 gallery I have a suggestion; (if not already made) to include a 'hit count' for each pinhole image page. Is this easily done and possible? It would be fun and great for the ego to see how many visiters each image in getting. I've started to get excited for April 27th, 2003! Sincerely, Andrew Amundsen Mpls./St.Paul, MN. ___ 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?!
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
