Re: [pinhole-discussion] coverage
- Original Message - From: "Richard Koolish" > Cameras that are half cylinders or whole cylinders, like the > classic oatmeal box cameras have different falloff patterns. Half cylindrical cameras have a fall off of very close to just Cosine of the angle, as a result, a 120° total angle of view pinhole camera would have a fall off of just 1 stop instead of 4 stops, very dramatic improvement. Anyone wanting virtually no fall off, should consider half cylindrical cameras. Guillermo
Re: [pinhole-discussion] coverage
Good answers have been given, but they have answered the question of why the fall-off more than the question "why 4 stops of fall-off)". So here is my $0.02 worth of answer. - Original Message - From: "Stewart C. Russell" > > > > Could anyone explain why "about 4 stops of falloff at ghe edges" ? > > that was from an off-list response. I was told that light falloff is > proportional to cos^4 of the off-axis angle. > > So for 120 degrees symmetrical coverage, that would be cos^4 (120/2). > As cos 60 = 1/2, that would be 1/(2^4), or four stops falloff. > > Or am I off somewhere? It worked well in this case Stewart, but that explanation wouldn't work for other angles, I think, but I may be wrong, I am known to be wrong from time to time, actually my wife thinks I am wrong very often! but that is a topic for a different NewsGroup!! Here is my explanation: Short answer: The intensity of light at OFF axis points on a film is equal to the intensity of light at the center of the film (ON axis) multiplied by the COSINE to the power of 4 of the angle of that off axis point (you may ask why cosine^4, why not cosine^3, but you didn't ask that, so I will keep going with this explanations). If we have a camera with a total angle of view of 120°, it means the most OFF axis point on this piece of film is 60° with respect to the center (60° on one side and 60° at the opposite makes for 120° total). So, as Stewart said, Cosine of 60° is 0.5 and Cosine^4 would be (0.5)^4=0.0625 which is nothing but multiplying 0.5 four times by itself (0.5 x 0.5 x 0.5 x 0.5 = 0.625). Let's see: if we had 100 units of light (whatever units) at the center of the film and the total angle of view is 120°, the intensity of light at the corners of the film would be: Intensity at corners = Intensity at center X [Cosine(60°)]^4 as we saw above [Cosine(60°)]^4 is 0.0625, so we have: Intensity at corners = 100 X 0.0625 Intensity at corners = 6.25 That means that for the above camera the light intensity at the corners is 6.25% of the light at the center, now your question: "why 4 stops": As it turns out, 1 stop of difference means double (or half) the intensity of light. For instance, if f16 gives you 50 units of light at the center of a film, you can bet that f/11 will give you 100 units. To find out how many stops of separation exist between 2 intensities of light, we just need to double the lower intensity until it reaches the higher intensity, the number of times you doubled the lower intensity is the number of stops. To double any number we just multiply by 2. So lets see how many STOPS are there between 6.25 units of light and 100 units of light: 6.25 x 2 = 12.5 (first doubling = 1 stop) 12.5 x 2 = 25 (second doubling = 2 stops) 25 x 2 = 50(third doubling = 3 stops) 50 x 2 = 100 (fourth doubling = 4 STOPS) There is your answer, that is why there are 4 stops of fall off from center to corners on a 120 angle of view flat film plane camera. Long answer: the short answer ended up being so long that I will omit a long one. :-) Guillermo
Re: [pinhole-discussion] Pinhole camera on the shoe
- Original Message - From: "Michael Healy" > Hey, Guillermo, head's up! This new Pinhole development just in from > tonight's San Francisco Chronicle... Well, I am not into digital imaging, so I tried a film pinhole camera on the tongue of my shoe once, but the ladies wouldn't stay put for the required 15 minutes exposure time!!. :-) BTW, pinhole in video survilliance means different than OUR Pinhole. Video survilliance use GLASS or PLASTIC LENSED cameras and they are called pinhole because you hide them behind something (usually a wall, ceiling or SHOE TONGUE!!) and only need a small hole (therefore pinhole) on that something to SEE thru. > "(He said he saw Rich) walking up to women and paying more attention to the > women than to the cars,'' That would include most of the men in a car show, wouldn't it? :-) Guillermo
Re: [pinhole-discussion] polaroid pinhole question
- Original Message - From: "Trent Dowler" >Did that just label me as amateur, or what?! Using an idea Imogen Cunningham used before: Everybody here is an AMATEUR...amateur is the french word for LOVER, of pinhole in this case. >Sorry folks. I should have searched before posting. We've just always called it > color shift. Your question was: "why does the Polaroid film packs produce strong magenta tones? In other words: "why does the Polaroid film packs have a COLOR SHIFT toward magenta tones?" The answer is not color shift. Why the film's colors shift is because Reciprocity Failure, each color layer "fails" differently, their combined failure produce a resulting color (shift), that in this case is toward magenta. Photographic Exposure is given by a pair of values, they are exposure TIME and exposure APERTURE, they have a RECIPROCAL relationship, that means, if one is increased by X number of stops and the other is decreased by the same X number of stops, the photographic exposure is unaltered (i.e., 1/125 secs @ f/16 is the same as 1/500 secs @ f/8). That RECIPROCITY fails, though, when the exposure time goes -generally- above 1 second (or bellow 1/1000 second, not important for pinhole), after that 1 second, the exposure time given by the RECIPROCAL relationship of time and aperture is no longer enough, you have to increase the exposure time, not only that but the failure is not lineal, the longer the "uncorrected" exposure is, the bigger the correction factor we need to use. Not only each (B&W) film has its own reciprocity failure characteristic, but each layer of a color film, too. If all the layers of a color film failed equally, there wouldn't be a COLOR SHIFT, but we would still have RECIPROCITY FAILURE. Guillermo (who is just another amateur)
Re: [pinhole-discussion] polaroid pinhole question
- Original Message - From: "Trent Dowler" > > Perhaps I've missed it, but why does the Polaroid film packs produce strong > magenta tones? Could it be improper developing time? Reciprocity failure.
Re: [pinhole-discussion] Sized needles
- Original Message - From: "Becky Ramotowski" becks...@cotse.net > If I drill my own pinhole and want the smallest possible hole with the > number 15 needle, do I understand correctly to just get the point > through, then sand the rough edge and that's the end of it? I'd do 2 more things: take the needle and insert its tip into the hole, rotate the needle couple of times, do it gently, the aim is not to make the hole bigger but to clean any burrs the sand paper -usually- leaves at the edge of the hole. Then apply a burst of air to the hole. Guillermo
Re: [pinhole-discussion] Westmark Industries/Raytex
- Original Message - From: "Stewart C.Russell" > I know that 35mm is not the ideal format for pinhole, but since you can now get the Voigtlaender/Cosina Bessa-L/SW-107 body for $75 new, it'd make a decent wide(ish) angle pinhole camera. No mirror to get in the way. That camera is perhaps the ideal "real" 35mm camera to use for pinholing, incredible price, made for wide angle FoV and if you want to "sin" doing glass lens photo, you can get nice wide lenses for a fraction of the price of other systems. I didn't know anything about it until yesterday. I am tempted! Do you know if you can buy viewfinders alone? or do you have to buy the lens/viewfinder combo? Guillermo
Re: [pinhole-discussion] optimal film size
Stephen, The answer is NO to almost all the questions, except the following: "suppose i want to have my images vingetted on the film surface, round image, black background, fuzzy edges and all, say on 120 film (6 cm x 9 cm) with the actual size being closer to 5 cm diameter, how would i calculate this?" Short answer, just use a focal length that is 24% the required image diameter. Long answerit is too late for that, it is 1:08am!!, my "on call" shift just finished, time to go to bed. Guillermo - Original Message - From: "stephen" > hello all! > a question about optimal film size: > im familiar with the charts of optimal pinhole sizes > with certain focal lengths, but is there an optimal > film, or surface, size? > am i correct in observing that a smaller sized pinhole > gives a wider angle of light and a larger pinhole a > more gradual angle? > so suppose i want to have my images vingetted on the > film surface, round image, black background, fuzzy > edges and all, say on 120 film (6 cm x 9 cm) with the > actual size being closer to 5 cm diameter, how would i > calculate this? > does the optimal pinhole/focal length charts imply > that if i were to decrease my focal length, or > increase my pinhole diameter, just slightly i would > get my vingette edge? or is there "excess" image to > spare and i would have to adjust more drastically? > i wouldnt i get them same result by using a fixed > pinhole and focal length with 35mm and 120 films, > right? > i suppose i should phrase it as: does the inverted > image on the film surface have a terminating diameter? > i know it gradually looses light. > am i making any sense? sorry, its getting late. > just wondering if anyone has ever worked on this > before... thank you and good night.
Re: [pinhole-discussion] WPPD 2003
Well, Taco, It is like Dirk Nowitzski, the German basketball player, star of the Dallas Mavericks, he may play and live in the USofA for the greater part of the year, but when it comes to International Events, I am pretty sure he plays for Germany. I am no star, just your run of the mill occasional pinholer, but in this International event, I choose to "play" as a Salvadorean. > Actually, it also seems that there are no 43 countries but less: I never > heard of a country called "Europa Island" and the e-mail address of > Mercedes is definitively in Spain, same for Guillermo, known as living > in Canada but giving as location El Salvador. (and then with the > subtitle "Partial view of Toronto's skyline...") > taco
Re: [pinhole-discussion] re: Pinhole Camera Instructions... f/stops and needles
- Original Message - From: "stephen" > hi phillip I am not Phillip, but pls allow me to try to answer your question: > curious to know what are you using to create the > pinhole? > or do you know the approx f/stop? > well, that is the question isnt it? > so many different charts have this or that f/stop > assigned to a fixed sized. > so has anyone come accross an 'accurate' mm (or inch) > to f/stop guide? There are several ways to find the f/stop of your pinhole camera set up. One method is to shoot an "average" scene under a sunny day, bracket several exposures and record the different times, process the film and select the "best" exposure, then find the f/stop of your pinhole making use of the fact that under sunny skies f/16 @ 1/iso seconds is the "correct" exposure. Another method is by knowing the diameter of your pinhole, then the f/stop will be given by the quotient of the distance between pinhole and film and the diameter of the pinhole. The hard part is measuring the pinhole. Knowing the diameter of needles you use to make the pinholes is a way to get an approximate size of the pinhole, measuring the pinhole itself is even more accurate. I wrote a small article on how to measure pinholes using your cheap (mine is anyway) flatbed scanner, what you then do is make a bunch of pinholes, measure them and use the one that approximates best to what you need. Here is the link to the small article: http://members.rogers.com/penate/diameter.htm > where can i get a #10 (0.46 mm/0.018 in) needle? > thanks! I know the following doesn't answer your question directly, but it may, indirectly: If you own a dremel or similar drill, you could also use wire gauge drill bits, a wire gauge drill bit #77 is 0.018" exactly what you need. see this 2 sets, for instance: http://www.mytoolstore.com/irwin/numbers.html there may be cheaper sets out there. Guillermo
Re: [pinhole-discussion] Re: Panoramic Characteristics?
- Original Message - From: "Wally & Wolfgang Thoma-Schuermans" > > > 3 micron = 0,003 mm for a focal length of 67,5 mm will give you a f/stop > of 22500 > Sure of the 3 micron? He probably meant 0.3mm for an f/225 aperture. Guillermo
Re: [pinhole-discussion] Pinhole Camera for medical purposes
- Original Message - From: > I am working as a Medical Physicist for my summer Co-op position. One of the projects I am working on is an attempt to use a x-ray flouroscopy screen and a thick piece of lead with a hole drilled through the center to try and image the position of a point source of radiation in a radiation therapy procedure. The radiation used is gamma-radiation which is an electromagnetic wave like light so it has most of the same properties. Interesting project you young people have the chance to work on, a young friend of mine flew to Switzerland just yesterday to work on the installation of a new particle detector at CERN. Let me congratulate you on your summer job position. > I am trying to optimize the Field of View and the Resolution and can't find _any_ resources for pinhole imaging with the pinhole in a thick material. (The thickness is required, otherwise the strength of the radiation will over-expose the screen and all we will see is white.) Any knowledge, links or even idle speculation would be appreciated. I am less than a neophyte on this stuff, but that doesn't prevent me from posting this: if what you have is a pinhole on a very thick piece of lead, this is basically a gamma rays collimator, it would allow only gamma rays parallel to the pinhole walls to reach the detector (fluoroscopy screen in this case?), therefore your point source of gamma rays would have to be in axis with the pinhole "tunnel" in order for an image of the source of rays to form. It seems to me that if the aim is to image the position of the source, no matter where it is, a collimator consisting in an array of pinholes should be used, in this case, an image of the source will be formed by the pinhole whose axis happen to be in line with the source of rays. As for the field of view, a pinhole drilled in any thick material precludes any field of view, due to simple geometry of the set up. Resolution: gamma rays have such a high frequency that probably any pinhole you are able to make will be much bigger than what any Lord Rayleigh derived optimum pinhole formula would give you (assuming they obey to the same diffraction laws as visible spectrum wavelength), therefore loss of resolution due to diffraction could be disregarded and all you have is geometric resolution given by the diameter of the pinhole. What I would do is to do google searches and send emails to researches and scientists with web pages on similar topics. I know the above is of no help to you, but wish you the best of luck in your endeavor, Guillermo
Re: [pinhole-discussion] WPPD2003
- Original Message - From: "Wally & Wolfgang Thoma-Schuermans" > Shelley, > I think you didn't get Rosanne's earlier posting. This is a technical > discussion and not a chat box. Sorry for being rude, I have been with this list since almost its inception, the above post does not represent what this list has been and is about. Anytime you have to apologize by saying you are sorry, I'd suggest you stop, don't press "Send", go back and delete the very same thing you are apologizing for. That's the beauty of written communication, it gives us that chance. I wish I could do that with things I have verbally said in the past! Your message, Taco, was totally uncalled for, Shelley's message is absolutely in tune with this list's reason to exist, IMO. On the other hand, this list has 2 moderators let's leave the task of putting us back on topic to them. Guillermo
Re: [pinhole-discussion] Zone plates & pinhole sieves
- Original Message - From: "Wally & Wolfgang Thoma-Schuermans" > > Very interesting. I have a Lubitel myself (bought in a second hand shop > in Prague for 10 USD) that I wanted to use for "serious" 6x6 work, but > it leaks light like hell, so why not transform it. Can you give me > details (how to open the lens) etc. Can I still use the shutter? > greetings, Taco Taco, It is actually very easy, the shutter/lens assembly come off by removing the lock nut at the rear and accessed thru the inside of the camera, use a screwdriver to turn the nut, once the assembly is off the camera, unscrew the very front of the lens, then you'll see another small lens also part of the front lens elements, this one is removed by removing a "C" clip. At the rear of the shutter there is another "C" clip that allow you to remove the rear lens element. I mount the new aperture in place of the rear element, this place the ZP, etc. 65mm or so from the film plane. I first mount the ZP on a plastic circle that fits snugly on the rear of the shutter, I usually use plastic from one of those 35mm canister's cap. Recently I have decided I will not use this cameras with their original glass, so I being making a hole in the center of the glass rear element and mount the aperture there. Guillermo
Re: [pinhole-discussion] zone plate question
- Original Message - From: "Meggan Gould" > Hello! I would like to tap into all the zone plate knowledge out > there...I have done a fair amount of pinholing, and have read up on > zone plates and feel more or less comfortable with how to make the > actual zone plate. What is the best way to then mount the zone plate > though? You mount it the same way you mount a pinhole. If you want to provide some mechanical protection to the ZP, you could first mount the ZP to a piece of the same material you use to make your pinholes and then mount that to your shutter, lens board, cardboard box, Quaker container, etc. > Has anyone done Holga zone-plating and have any suggestions? Not Holga, but Lubitel. Depending what speed of film you use you may find that outdoors exposure times get very short, bellow 1/2 secs in many cases, having a shutter is something nice in this cases, that's why I like a lubitel with its not that accurate but certainly usable shutter. Guillermo
Re: [pinhole-discussion] WPPD
- Original Message - From: "Guy Glorieux" > > Hey Guillermo, > Remember the snow storm we had last year on WPPD2. Montreal was bad, > but if I remeber correctly, you had an even worse weather. Guy, Well, the only thing predictable about weather is its unpredictability! Yesterday though, we had a "Glorieux" sunny, open skies day, just a day suitable for pinholing, which I did, hope I got something right there up to my level of -artistic- incompetence. Will see when the color film comes back from the lab, can't wait. Guillermo
Re: [pinhole-discussion] Zone plates & pinhole sieves
- Original Message - From: "Ed Kirkpatrick" > > I am interested in sieves. Are they one size fits all or specific to > the focal length? Ed, Sieves do focus light using diffraction, as supposed to glass lenses which use refraction, therefore, Sieves are manufactured for specific focal length. > What is a good source for them? You can get pre-made Sieves of 50mm, 75mm and 90mm focal length from Pinhole Visions site, or you can also get the same pre-made Sieves mentioned above plus custom made of any other focal length, directly from the developer of the Pinhole Sieve technique at http://members.rogers.com/penate/customZP/customZP.html . Prices are the same and you can pay using credit card and PAYPAL from either site. The developer of the P.Sieves manufacture the sieves sold at PV site and the ones sold by himself, obviously. > What are they made of? Short answer, they are made on a piece of high contrast lith film. For a long answer go here: http://members.rogers.com/penate/sieve/photonsieve.html Guillermo
Re: [pinhole-discussion] pinhole light falloff vs. circle of coverage question
- Original Message - From: "Uptown Gallery" > If one set up a 4x5 bellows camera for pinhole with an appropriate pinhole > for double extension (say 300 mm), placed the bellows at 300 mm but used a 4 > x 5 filmholder, would that place the worst of the edge falloff outside the > 4x5 image? It seems to me that this would work, at least to reduce the > effect somewhat. Although fall off, technically speaking, starts right as soon as we depart from the very center of the filmplane, it'll not be noticeable until a distance around half the diagonal of the image format. In other words, as long as your focal length is equal or greater than what it is considered the "normal" focal length for the format, the fall off can be disregarded. As a matter of fact, if you are enlarging a negative made with a 150mm focal length pinhole, and you use a 150mm enlarging lens to do it, the fall off in the negative will be corrected by the fall off of the enlarging lens. This is one of those cases in which 2 wrongs make a right!! Guillermo
Re: [pinhole-discussion] new to list/pinhole photography
Shelley, Pinhole photography is in technical aspects not different than glass lens photography. Focal length, aperture (not aperture size), exposure, angle of view, light fall off at the edges of film, reciprocity corrections, etc., are all concepts that function the same whether the lens is a pinhole or a glass lens. Based on the above, it makes sense that the program have you doing pinhole in 102 rather than in 101 as the latter course (hopefully) included all of those concepts. If you do a google search you are going to find several sites that have tables with needle sizes and their diameters, George Smith's being one of them http://mywebpages.comcast.net/hmpi/Pinhole/Articles/Aperture/pin_aper.htm , but if I were you and had access to a flat bed scanner, I would use it to measure its actual size. This small article I wrote tells you how to achieve that: http://members.rogers.com/penate/diameter.htm Guillermo - Original Message - From: "Rauch, Shelley" Things not discussed: focal length, aperture size, exposure. I've glossed about on the internet and read some good articles on all of these. I'm currently trying to figure out what my aperture size is. I used, the teacher thinks, a #10 sewing needle to create the hole. Is there an 'average' size for this sort of needle? I'm going to be experimenting tomorrow morning, but the darkroom will only be open for a few hours tomorrow afternoon, then closed again until Tuesday. I'd like to avoid wasting paper. Any advice about my aperture, exposures, or anything I'm not thinking to ask? Thanks... from a very frustrated student... Shelley C. Rauch Acquisitions Dept. (757)890-5116 Tabb-York County Public Library 100 Long Green Blvd. Yorktown, VA 23693-4138 ___ 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] I need some e-mail addresses please!
- Original Message - From: "Tom Lindsay" > > Hi, it's Tom Lindsay here and I need to have those people who know me > send me your e-mail addresses so I can contact you directly. I'm at my > "honeys'' house and don't have all the addresses that I would like to > have. > While your not too busy, please take a look at my "new" exhibit > http://www.???/exhibit/cancer and please sign the guest > book too. The correct URL to Tom's essay is: http://www.???/exhibits/cancer I have not finished reading it, but the 4 or 5 pages I have seen and read indicate that it is something out of the ordinary, in fact it is an extraordinary essay. DO NOT MISS IT. Guillermo
Re: [pinhole-discussion] BODYCAPS
- Original Message - From: > Thanks for the replies, does anyone know of an online resource with instructions to build a bodycap? Here are the instructions: buy bodycap, drill hole in its center, tape pinhole on the cap. BTW, Canon F body caps are for FD mount bodies, your AE1 uses FD mount, AFAIK. Guillermo
Re: [pinhole-discussion] disposible camera
- Original Message - From: > I recently got a copy of the disposible camera handout, thank you very much. > But I was at the gallery where I work the other day, taking a disposible cameera apart. And one of the security guards dave asked me what I was doing, when I said I was making a pinhole camera, he thought I was perhaps some king of pervert. King of perverts! that's really funny. > Does anyone else have any stories of pinhole-related misunderstanding. Yeah, I once was doing some pinholing inside the beautiful building of Trinity College at the University of Toronto and the, yes you guessed, security guard told me not to continue because he thought my 4x5 made out of scrap baseboard moulding was a professional camera! I was able to use my Nikon SLR w/o problems tho. Guillermo
Re: [pinhole-discussion] f64,f90,f128?...
Andrew, f/stops progress by a factor of 1.414 which is the square root of 2, therefore, the numerical value of f/stops double every other stop. If we start at f/11 (we could have started with any f/stop), the next one is f/16, since they double every other stop, the progression would go like this: 1 (half 2) 1.4 (half 2.8 2 (half 4) 2.8 (half 5.6) 4 (half 8) 5.6 (half 11 or so!!) 8 (half 16) 11 -->known starting consecutive f/stops 16 -->known starting consecutive f/stops 22 (double 11) 32 (double 16) 45 (double 22...or so!!) 64 (double 32) 90 (double 45) 128 (double 64) 180 (double 90) 256 (double 128) .add infinitum So, if you know 2 consecutive full f/stops values, you can find out any other full f/stop in the progression. Guillermo - Original Message - From: "Andrew Amundsen" > Can anyone help? What's the proper progression of f-stops above f90? Is f128 > next and tell a couple more if you have the info at your fingertips. > > I've picked up a Finney Pinhole Bodycap for my Leica M. It's listed as a > 30mm, approx. f128 and my Minolta meter goes to f90. So is f128 the next > f-stop in the natural progression of reciprocity? Twice as small? If not > someone please correct me! > > Thanks for the help, Andrew Amundsen
Re: [pinhole-discussion] POLAROID AND PINHOLE
- Original Message - From: "callum moffat" > I MANAGED TODAY TO BUY A CHEAP(£8)POLAROID LAND CAMERA > SUPER SWINGER > QUESTION: IS THE TYPE OF FILM I NEED STILL AVAILABLE? > THE NOTE ON THE CAMERA BACK SAYS TYPE 87 BUT I CANT > FIND IT LISTED ON POLAROIDS UK SITE Check this site: http://www.rwhirled.com/landlist/landhome.htm Guillermo
Re: [pinhole-discussion] 35 mm pinhole camera
- Original Message - From: "Zami Schwartzman" > the buurs on the oposit side had to be very carefuly treated with no. 400 > sandpaper to get a perfect hole . Although not a sraight forward job , I can > get perfect holes as small as 0.05 mm diameter FYI, such small pinhole would be "optimum" for a camera with a 1.85mm focal length!! A bit impractical, if you ask me!! > I experimented with a 0.1 mm hole , got some good close up pictures well > exposed with Kodak gold 400 ASA( using f: 120 on the light meter ) but the > results are quite " out of focus " on 10x15 prints . -Your f/stop should be f/280 and not f/120. -f/stop is given by dividing the focal length by the pinhole diameter (28/0.1 = 280) -As pointed out by erick...@hickorytech.net, you should be using a pinhole 0.00784" which is equivalent to 0.2mm. The 0.1mm pinhole is producing too much diffraction. -If you want relatively "sharp" 10x15 size results, I would suggest you shoot medium format or larger. > I wander if going further to a 0.05 hole will worth the panelty in the f > number . Only if you could mount that pinhole about 2mm from the film plane. The resulting image, BTW, would be a circular image no bigger than some 10mm in diameter. > Is there an optimun hole size for best sharpness ? or is it the smaller > the better. Take a look to this http://members.rogers.com/penate/pinsize.htm Guillermo
Re: [pinhole-discussion] polga
300 US bucks for a Polga!!? Imaging how much a "Piana" could go for! Guillermo (who do know Dianas are not in production anymore)
Re: [pinhole-discussion] 4 questions from a beginner
- Original Message - From: "Bre Pettis" > Question 1 > I've got a .013 needle hole and 1" from > the hole to the film. I've got it loaded with 400 > speed b&w film. How long should I try for > an exposure on a sunny day? Am I right in gauging the > f stop at f/77? I've got a light meter, should I use > it and should I make any adjustment for using a > pinhole? If your pinhole is actually 0.013", yes f/77 is your f/stop. Once you know the f/stop and speed of film, when it comes to find the exposure time, it is irrelevant what camera you have (IE: cardboard pinhole or Hasselblad) as well as irrelevant is which lens you are using (IE: a Carl Zeiss or a dirt cheap pinhole lens) and what's the focal length of that lens. So if you got a light meter, use it "business as usual". BTW, f/77 is equal to f/64 +1/2 stop, if I were you, I'd approximate that to f/90. If so, "Sunny/16" says that under bright sunny skies and using ISO-400, exposure should be f/16 and 1/400 secs, therefore for your f/90 pinhole, the exposure should be 5 stops more. > Question 2 > > I've made a 250 sheet photo paper box pinhole camera > with a .013 hole. I'm not getting nearly as much > light around the edges as in the middle. I thought it > might be the pinhole, so I made another with the same > problem. Is lack of light on the edges normal? Yes it is (as explained by erick...@hickorytech.net). The wider the angle of view of your camera the more pronounced that fall off will be, even if you make the hole bigger. Something else that contributes to make it worst is a not so clean pinhole and a pinhole made on a very thick material. Guillermo
Re: [pinhole-discussion] Pinhole mounted in bodycap on EOS cameras
- Original Message - From: "Rune Tallaksen" > How do I measure the distance from the filmplane til the pinhole? Here is what I did to measure the same in my Nikon camera, before I got hold of the Nikon specs: Make a hole 1/2" or so in the center of your bodycao, mount that bodycap on the camera'd body, set the camera for the maximum exposure time it allows (30 secs in my case), press the shutter, take a cotton swab and insert it thru the bodycap hole until it touches the film plane, make a mark on the cotton swab at the height where the pinhole would be installed, remove cotton swab and measure the distance with a rule. Children, don't try that at home!! Nikon cameras have a distance of 46.5mm from the film plane to the lens flange, Canon EOS have a distance of 44mm. > What will the optimal pinholediameter be? It depends which formula you use. anywhere from 0.009" to 0.010" would be fine for an "optimum" pinhole, if that is what you want. > Will my built in exposure be able to measure the light and set a > "correct" exposure? It should, under bright light with relatively fast film. It really depend on the EV sensitivity of the EOS meter system. > What else should I think of? Stop thinking, do it and try it, it works!! Guillermo
[pinhole-discussion] Sad note
In case someone here did not know: World-renowned wilderness photographer and writer Galen Rowell, and his wife and business partner Barbara Cushman Rowell, a photographer and writer in her own right, died early Sunday morning in an airplane crash outside of Bishop, Calif. http://www.mountainlight.com/ Guillermo
Re: [pinhole-discussion] Strange Problem and I need some help.
- Original Message - From: "Eric S. Theise" > > And the source online that talks about using silver foil and blackening > that with selenium toner always seemed very elegant to me. That's Larry Bullis, if memory serves me well. I tried to find a local place that'd roll some silver for me but couldn't find one. That method works well 'cause the toner blacken the silver at a molecular level, so no clogging on the hole can occur, pretty elegant, as you said. Guillermo
Re: [pinhole-discussion] Strange Problem and I need some help.
- Original Message - From: "George L Smyth" > > Another way of masking the pinhole surface is to simply blacken it with a > Sharpie. That's what I do. I ink as close to hole as possible w/o actually touching its edge. Having said that, I never noticed any difference when I don't blacken the pinhole material, provided the unpainted area is not larger than 3/4 x 3/4". Guillermo
Re: [pinhole-discussion] stereo pinhole
- Original Message - From: "Bre Pettis" To: Sent: Tuesday, August 13, 2002 4:05 AM Subject: [pinhole-discussion] stereo pinhole > Hi, I'm Bre Pettis out of Seattle and I've become > completely obsessed with pinhole photography. I'm > just writing in because I'm proud of making a neat > pinhole stereo camera. Thta sounds interesting, when can we see some examples? do you have a web page? Guillermo
Re: [pinhole-discussion] 5x4 too small to contact print?
- Original Message - From: > I'm currently making pinhole pictures on 5x4 film, with a Leonardo > camera. At the moment I scan the negs and print digitally, but for a > bit of a change I'm thinking about contact printing them on Printing out > paper of some kind, maybe start with cyanotype. I'd be grateful for > feedback on what people think about this, too small? or just intimate. 4x5 are just too intimate, IMO :-) I did just that for a while before I bougth a 4x5 enlarger, BTW. I find 5x7 to be a much better size for contact printing, just intimate enough. Guillermo
Re: [pinhole-discussion] (OT) Enlarger help?
- Original Message - From: "Steve Bell" > > I know another off topic post, but it's kind of on topic, right? i mean, > enlargers are often times used with pinholed negs! anyway, my question is, > can anyone give me some advice regarding enlargers? i'm building a darkroom > in my basement. I'm not exactly sure where to begin when it comes to > enlargers. i will be enlarging both color and black and white 35mm, 120, > and hopefully other medium format negs. can anyone let me know what their > favorites are. i am on somewhat of a budget, but i can afford a semi > expensive piece of equiptment. My $0.02 worth of advice: - Buy used, which will save you good money. Many people are going digital and selling their conventional stuff pretty cheap. - Buy the next size up, which in your case would be 4x5. Chances are that eventually you'd want to try one size bigger (at least) than you now think you would. - Buy 6 elements lenses, like Rodagon or Componon-S. There's a big difference between results obtained with 4 and 6 elements lenses. Disregard this advice if you'd be enlarging just pinhole stuff. Guillermo
Re: [pinhole-discussion] Newbie Intro. and a few questions
- Original Message - From: "Fox, Robert" > Are there any practical reasons to shoot at 4x5 rather than 8x10? 4x5 is more, well, "practical": smaller, less costly to operate, easier to carry and you don't have to get a second mortage to buy an enlarger (if you wanted larger than 8x10 prints, and eventually you would), 4x5 enlargers are readily available. Also, you could buy an inexpensive "real" 4x5 camera and use it for pinhole work, i.e.: grey calumet, super graphic, any of the other graphic press cameras, etc. > I suppose it would be easy enough to do both That's right. My first 8x10 was a cardboard box. > but I'm wondering about people's > preferences for architectural and portrait work. The multi-format Zero2000 > looks like a good starter as well given the choice of formats for standard > roll film. You can't go wrong with a Zero2000 they are truly functional pieces of art! Welcome to the list. Guillermo
Re: [pinhole-discussion] (OT again)Alt Process list??
- Original Message - From: "Steve [Eazy E] Bell" > > So here's a question for all of you. I've heard mention of an alternative > process list existing, and i'm wondering if anyone might be able to help me > find it. Here is how to subscribe: http://www.photography.gr/links/mlists/details-en.htm?list_id=7 Guillermo
Re: [pinhole-discussion] old negatives
- Original Message - From: "Jacob Runyan" > She said the film was probably just a standard kodak > film...but my question is, which side is the emulsion > side? There is a really shiny side, but I can not > seem to find any texture in the "emulsion" like I > would see on a current day negative. > > Any help you could give would be greatly > appreciated I am not familiar with old negatives, so my advice is this: check all the negatives and see if at least one if them has written signs, if so, you could easily tell which side is the emulsion side. BTW, there could be some other thing that could indicate which side is the emulsion, i.e., landmarks, traffic direction (in UK), wedding ring, etc. Perhaps the best piece of advice you could receive, beside being careful handling them, is to make a good scanning of those negatives, befor eyou start manipulating them. Good luck. Guillermo
Re: [pinhole-discussion] Checking pinhole sizes (again?)
- Original Message - From: "John Moore" > The pocket comparator (Item No.: L1873D) is $28.50 & > the reticle insert (Item No.: M1599D) is $12. $50.50 > seems like a good deal for an item that can be used > for more than just checking pinhole sizes... of > course, I can't seem to think of anything else to use > it for- but, no matter. Although 7X is a bit too powerful, it could be used as ground glass focuser. It certainly is a good deal, a more or less similar product cost a lot more here: http://www.edmundoptics.com/IOD/DisplayProduct.cfm?productid=2121 Now, 7X is for my taste a bit on the low power side to measure pinholes, I think I'd prefer something with more power, perhaps like this: http://www.scientificsonline.com/Products/DisplayProduct.cfm?productid=1357 Guillermo
Re: [pinhole-discussion] hello.....
- Original Message - From: "Mark Interrante" >Ok, I've a question. I recently saw Martha Casanave's Lenin photos >(http://marthacasanave.com/lenin.html) >and I think they are beautiful. She uses a non-optimial pinhole, and I'd >like to know if people have any idea how much larger I would need to make >a pinhole to achieve this effect? I missed this post, here is a somewhat late suggestion: Eric Renner's book has a set of pinhole images of the same subject (I believe it is the portrait of a nun or a nun looking girl), each image was made with a differente size of pinhole and if memory serves me well the f/stop is shown for each image, if that is so, just take a a look at the different images, select the one that best represent the effect you want and find how mant stops there are between the sharpest one and your selection, That would be the number of stops your pinhole should be larger than the optimum, in order to get a similar effect. i.e.: your selection is f/128 and the sharpest is f/320, that gives you almost 3 stops between 128 and 320 (128, 180, 256, 360), so the pinhole you want should give you an f/stop 3 stops bigger than the optimum. The above is just a good starting point as there are some othe factors to take into account. A more hands-on approach would be to make a series of pinholes giving 1 stop, 2 , 3, 4, 5 stops and so on, larger than the optimum. That is easily achieved by multiplying the optimum diameter by the f/stop sequence starting with 1.4 so the sequence goes 1.4 - 2 - 2.8 - 4 - 5.6 - 8 - etc., then make exposures of the same scene, using all of the pinholes, develop the film, print the images to the size you'd normally be enlarging the negatives and then select which one is the ONE for you. After the test you should know how many stops larger should the pinhole be, that info could be applicable for other pinhole focal length. An example would be: Camera = your SLR Focal length = 50mm optimal pinhole = 0.010" series of pinholes: (0.010 x 1.4) = 0.014" (1 stop larger that optimum) (0.010 x 2 ) = 0.020" (2 stops larger) (0.010 x 2.8 ) = 0.028" ( 3 stops larger) (0.010 x 4 ) = 0.040" (4 stops larger) Anyway, you get the idea. Guillermo
Re: [pinhole-discussion] that old reciprocity failure question again
Shannon, Reciprocity corrections as well as development adjustments are just suggested starting values, pretty much as the ISO speed of the films is (i.e.: 4x5 TRI-X works for me as EI-200, and not as ISO320 as Kodak suggest). >From that perspective, both Kodak and the mentioned book are "correct". The idea with any of this charts is to use them as starting point and make necessary changes as experience/process you use requires. Guillermo - Original Message - From: "Shannon Stoney" > Hi. I have two reciprocity failure charts. One is from Kodak and the other > is from Steve Simmons' book, Using the View Camera. They give very > different adjusted times for Tri X, when you get to very long exposures. > For example, if the metered time is 30 seconds, Kodak says to expose for 200 > seconds, and Simmons says 290, almost half again as long. Also, the > adjusted development percentages are very different. Kodak says 10% off > even for an adjusted exposure of only 2 seconds, and 20% off if your > adjusted exposure is 50 seconds, whereas Simmons doesn't even begin to > decrease development until exposure reaches 13 seconds, and then only by 5%. > If exposure is 50 seconds, he says to reduce development by about 9%. This > is confusing. I wonder whose numbers are right?
Re: [pinhole-discussion] Camera Size?
- Original Message - From: "ROBERTSON,TRAVIS J" > Thanks for your reply. I am learning about the science of pinhole cameras > and I must tell you my head hurts at times trying to figure it out. Stop hurting yourself!!, we really don't need to figure out any science, that was done by Lord Rayleigh back in the late 18 hundreds. Take any calculator (the one provided "free" by Mr.Gates is fine) and any of the formulas widely available in many pinhole sites (www.??? is a good starting point) and you are set. > As far > as the result, look at this web site. http://marthacasanave.com/lenin.html > . I really like the dreamlike quality of these photos but I would like to > have the images a little sharper. Shooting 16x20 is maybe not the best way to get "dreamy" images. You'd be better off shooting smaller formats and enlarging the results. You should experiment with different pinhole sizes until you get the desired effect. Another way to get "dreamy" picture is by using Zoneplate lenses (pinhole cousings), mines are not that dreamy but may give you an idea, check http://members.rogers.com/penate/ZP120.html and http://members.rogers.com/penate/ZP120_2.html >What I can not figure out is how > they did this. See how even the light is. With my oatmeal pinhole camera, > more light is located in the center to the photo and gradually gets darker > on the sides. Your pinholes probably are not that clean (burrs around its edge) and maybe made using somewhat thick material. Oatmeal cameras should have less progressive fall off compared to flat film plane cameras. One way to prevent fall off, other than using clean pinholes made using thin material is to make cameras with focal length distance equal or larger than the diagonal of the format. If you don't remember what Pythagoras Theorem is about, just take a rule and measure the distance between the corners of your format, the focal length of your camera should have that distance or above. > Today, I'm going to find something that will measure the > pinhole size. I have been cutting up a coke can and poking the hole in it. > I then sand the back down to try and make a clean hole. I suggest you cut the piece of the can, sand it to remove the plasticky coating , then do a poking and at the same time drilling action, sand the back and then gently insert the tip of the needle and rotate it several turns, this just to clean the hole, "sand" it again only this type use a pencil eraser and then do the rotating action with the needle again, finally, a burst of canned air at both sides. Guillermo
Re: [pinhole-discussion] Camera Size?
- Original Message - From: "ROBERTSON,TRAVIS J" > I would like to make 16X20 prints (That is I want to put the paper in the > camera) and I'm trying to figure out how large of a pinhole camera I would > need. Any suggestions on how to figure this out? Travis, Asking "how large a pinhole camera I'd need for 16x20 format" is in essence not different than asking: I have an SLR what lens should I buy?. The answer is: it depends on the application and/or results you want to achieve. Having said that, if I was making a 16x20" camera, I'd make it wide angle, perhaps something equivalent to 75mm to 90mm in 4x5 format (in case you are familiar with this format), in other words, I'd make it so it has anywhere from 300mm to 360mm in focal length or distance pinhole to film/paper. You were not asking for pinhole sizes but: As for getting scientific about pinhole, as Chris was refering to, I don't like optimum pinholes either, but I do measure the pinholes I make, I'd hate to poke a hole in a metal foil and by chance get the perfect optimum hole for my camera. By knowing what the "perfect optimum" hole is and by measuring my pinholes, I can not only know the f/stop of my camera but equally important I can make sure I avoid using the perfect optimum pinhole!! Guillermo
Re: [pinhole-discussion] Reciprocity
- Original Message - From: "James Noel" > What a complicated answer. > Simply put, most film is designed to react to light in a linear fashion > from about 1/2 second to 1/1000 second. Thanks James, I knew somebody would have a way to explain it in an easier way than me, even if technically speaking that explanation is not quite right, but nevertheless it suits the purpose. Guillermo
Re: [pinhole-discussion] nail hole camera
- Original Message - From: bendur...@aol.com >My names Ben >I have been a member of the discussion group for a few weeks, but have never posted anything, >I just wondered, what is the diameter of the 20 foot tube. Also I dont understand what reciprocity is. >Cheers Ben Ben, phographically speaking, EXPOSURE is given by a pair of exposure values, they are TIME and APERTURE and they have a RECIPROCAL relation between them given the same EXPOSURE, in other words, if you increase one value by one stop and reduce the other one by one stop, the EXPOSURE does not change. That is why if your meter tells you need f/8 and 1/8 secs, you could opt to use f/11 and 1/4 secs or f/16 and 1/2 secs, this reciprocity tho fails when the exposure time is (geneally speaking) 1 sec or greater or 1/1000 secs or smaller, some films fail later than others. For instance, if f/16 and 1/2 sec is the indicated exposure, the reciprocity law tell us f/22 and 1 sec is its equivalent, unfortunatelly, for a film like TRI-X, failure kicks in at 1 sec and according to Kodak we should give 2 secs instead of just 1, so for TRI-X for an indicated exposure of f/22 and 1 sec, the reciprocity failure corrected exposure would be f/22 and 2 secs. Now, reciprocity failure doesn't fail arithmetically, otherwise for TRI-X it would be just a matter of doubling the indicated exposure time. Reciprocity fails geometrically, the larger the indicated exposure time the larger the failure. Here is a graphic showing the reciprocity corrections needed for TRI-X: http://www.kodak.com/global/en/professional/support/techPubs/f9/f002_0062gc.gif If the above does not help you, just read some of these sites: http://www.google.ca/search?q=reciprocity+photography&hl=en&ie=UTF-8&oe=UTF-8 Guillermo
Re: [pinhole-discussion] I have a question.
- Original Message - From: "ROBERTSON,TRAVIS J" > I have a passion for photography, but the cost of large format cameras and > enlargers prevent me from doing the work I want to. Today I found your web > site and I have that excited feeling about pinhole photography. You see I > want to create very large photos, but I have a question. Can you create a > very large pinhole camera and just use photo-paper instead of film? How large is large for you, Travis? Would this one http://shorterlink.com/?W9BIMF be large enough? The answer is yes, you can make them as large as you can get film or paper for. Guillermo
Re: [pinhole-discussion] pinhole and strobe?
- Original Message - From: "Margaret Crowe" > Hi all, I hope I'm posting this in the right place!! Just wondering if > anyone can explain to me why it's not possible to take photos with my > pinhole using flashes (strobe)? MARGARET I am afraid that can't be explained, as it is perfectly possible to make exposures (pinhole) using flash/strobes. Guillermo
Re: [pinhole-discussion] pinhole size
- Original Message - From: "R Duarte" > I use Guillermo's method. It's a lot easier than it sounds. :) If that one sounds difficult, don't read my small article explaining zone plates lenses, I can't understand that one myself!! :-) Guillermo
Re: [pinhole-discussion] pinhole size
- Original Message - From: "Jean Hanson" > I have the math on how to figure the ideal size of the pinholes but how > do you actually measure them. Does everyone but me have a microscope, a > micrometer? what? Jean Risking being redundant with some of the many good suggestions you have received so far, I'd like to point you to a small article I wrote on that topic: http://members.rogers.com/penate/diameter.htm Guillermo
Re: [pinhole-discussion] HP5, Delta films and reciprocity
- Original Message - From: "Shannon Stoney" > What do you call this sort of shareware and how would you find it on the > internet? A search with the argument "best curve fit shareware" or just "curve fit" would do it. In the past I have used one called wincurvefit. If you want to do some reading, go to www.curvefit.com Guillermo
Re: [pinhole-discussion] HP5, Delta films and reciprocity
- Original Message - From: "Shannon Stoney" > This is interesting, a variation on the formula I was given. Where did you > get this formula? I wonder if such formulas exist for all films? > I have been using this formula successfully for about a month. It seems to > give good times. I have no idea why this "works" mathematically. The formula you use is known as "Best Curve Fit", it works by finding a formula whose curve fit best to all the points in a graphic of "metered vrs reciprocity corrected values". In other word, you first find by experimentation as many values as possible and then apply the "Best Curve Fit" method of choice (there are many, BTW) to find a formula that matches them best. Once you have a formula, you can inter and extrapolate to find any other corrections you want. There are shareware programs available that allow you to find the formulas w/o having to do it manually and w/o having to like or to be good at math. Guillermo
Re: [pinhole-discussion] pinholes and film speed
- Original Message - From: "Shannon Stoney" > So, I guess it doesn't really matter WHY this is so, as long as I can figure > out HOW to make a negative that works for me. That's correct! My intention was not to over analize the WHY but to just point to you there are so many variables involved an a minor "deviation" from all or several of them can easily account for the seeminly illogical at simple inspection result (to me at least). Guillermo
Re: [pinhole-discussion] pinholes and film speed
Shannon, Numerically, an EI of 1000 may seem as a big jump from ISO-400, but it is really just 1 1/3 stops faster, which probably can be accounted by a combination of factors like: "how thin you want the negatives low zones to be", a bit of anomalies in the reciprocity correction (I am not saying your method is incorrect) and the pinhole actual diameter being a bit bigger than what you think it is. Beside the above, 400 is the ISO speed of HP5 when processed as per the ISO standards, but it could prove to be a bit faster with your specific processing. An small contribution from all or several of the mentioned factors could easily make your 400 film appear to be 1000 film, instead. Guillermo - Original Message - From: "Shannon Stoney" > I have been testing with HP5+ film to see what film speed to shoot it at. > To my surprise, it seems as if its speed in my pinhole camera is about 1000! > It's rated at 400. The way I figure exposures is based on the fact that my > pinhole is f352. That's supposed to be 30 times whatever f64 is. So I > multiply the f64 time by 30 and then adjust for reciprocity failure, using a > formula I found online from Ilford: raise the metered time to the 1.48 > power. This accords with most reciprocity failure charts that I've seen. > > But to get my shadows thin enough, I have to shoot this at 1000. I have had > a lot of old cameras with old shutters that required different speeds than > the regular one because, I assume, the shutter is a bit slow. But a pinhole > doesn't have a shutter really! So, I wonder why you end up having to shoot > as if the film is much faster than it is? Has anybody else noticed this? /
Re: [pinhole-discussion] [pinhole discussion] New Lith Print
> shannonsto...@earthlink.net wrote: > > >I like this a lot too. I assume when you say Lith print, you mean you made > >a lith negative to print it? What kind of print is it? A visit to this site would answer some of your questions. http://www.pauck.de/marco/photo/lith/lith.html
Re: [pinhole-discussion] reciprocity failure and development times
- Original Message - From: "D Hill" > > Amen Leonard! You're the king! King of the Hill :-)
Re: [pinhole-discussion] Scanner pinhole??!
Opening the scanner's lid and aiming it to something you want to make an image of will result in a "PSEUDO-PINHOLEs" image. Sensors of the CCD are very small (can you say pinhole) and very directional (can you say tunnels). The non-high tech equivalent would be to make a pinhole camera with countless number of pinholes side by side on an extremely thick metal plate (lets say 1/2" thick), each pinhole will only capture 1 "image point" with virtually no overlapping. This is a self portrait Pseudo-Pinhole image made by aiming my cheap/uncleaned glass scanner to myself from a distance of about 15": http://members.rogers.com/penate/me.jpg Just a thought! Guillermo
Re: [pinhole-discussion] Slightly Off Topic
Scanners focus is optimized on the outer surface of the scanner's glass, placing the emulsion side face down may make a difference in the results (or not!). Guillermo > -Original Message- > From: pinhole-discussion-admin@p at ??? > > Does anyone have experience scanning glass plate negatives? Can it > even be done? A friend asked me to make contact prints from some > glass negs he bought at an estate sale. Since my darkroom hasn't been > reassembled after the big move, I thought scanning might work (haven't > tried it yet, though). I have an Epson scanner with a transparency > adapter (the extra light source on top).
[pinhole-discussion] Re: Non-sensical character of pinhole Was: Test
- Original Message - From: "I Zarkov" > Never mind this nonsense of 12 guys out standing in a field kicking a > beachball around. Tell that to the hundred of thousands of kids in your country kicking the beachball around. There are more kids in USA playing soccer than enrolled in little league and american football combined! > Harumpf! Understand, you may want to have your law makers and educators addressing the problem before it's too late :-) BTW, I am amongst the millions that watch the World Series, Superbowl, NBA and NHL playoffs, but I am also amongst the 95% of the population of the world liking and watching selected games from that non-sensical World Cup. It is good to do non-sensical things sometime, like Pinhole for instance! Guillermo
Re: [pinhole-discussion] 126 pinhole camera
- Original Message - From: "ROGER ARMOUR" > I am still using this camera ( camera box made from black card and attached > to a cartridge of 126 film - increasingly difficult to get hold of! The > pinhole is made from aluminium pastry foil) despite manual wind-on problems > etc. Could Guillermo or one of the experts please tell me who first > described it. Do you have the reference to a paper or did it first appear on > the internet? I'm hoping to write a paper and would like to give credit to > the person. > Thanks, and happy pinholing everyone Roger, as far as I know, it was Kodak who first described it, there are several sites having a copy of the document, PV site has it too, here is a link to it: http://www.???/resources/pinhole126/pinhole.htm Guillermo
Re: [pinhole-discussion] Test
- Original Message - From: "ragowaring" > It has been very quite > > All busy I hope; or perhaps resting Could it be due to The World Cup of Football (the one played with feet not with hands), the biggest, wildest, and most watched sporting event on the planet. It makes the Super Bowl look like Little League. It makes the World Series look provincial. It makes the nationalistic fervor of the Olympics look sedate. All the world but USofA+1/2Canada is tuned/glued to their TVs. Guillermo
Re: [pinhole-discussion] Focal lengths
- Original Message - From: "Andrew Amundsen" > Can someone tell me what the 12mm lens (in 35mm format) equivalent would > be in 4x5" format? > > I'm using a dual focal length 4x5" pinhole camera which only gives it's > focal lengths in 35mm format terms (12mm/24mm,super wide/wide). I have a > chart down to 20mm from my Calumet Catalog, so I know my wide position > is a 75mm in 4x5". I just need to know the 12mm! Andrew: If you believe that 24mm is equivalent to 75mm, then that means each millimeter of focal length in 35mm format is equivalent to 3.125 millimeters in the 4x5 format ( 75 / 24 = 3.125 ). You can use this constant to find equivalences, just multiply by the constant when going from 35mm to 4x5 and divide by the constant when going from 4x5 to 35mm . In the case of 12mm, that would be equivalent to 12 x 3.125 = 37.50mm in 4x5 I believe the constant Calumet uses is incorrect, it should be about 3.75, making your 24mm and 12mm equivalents to 90mm and 45mm, respectively, in 4x5 format. 24mm x 3.75 = 90mm 12mm x 3.75 = 45mm BTW, if you had a 4x5 lens 300mm FL and you wanted to know its equivalence in 35mm format, you'd divide 300 by the constant, like this: 300 / 3.125 = 96mm (using Calumet constant) 300 / 3.75 = 80mm (using the correct constant, IMO) Guillermo "If you give a man a fish he will have a single meal. If you teach him how to fish, he will eat all his life.-- Kuan-tzu (Chinese Philosopher)"
Re: [pinhole-discussion] increased sharpness?
- Original Message - From: "Jim Kosinski" > it makes any difference... does anyone know the range of > wavelengths that b&w paper is sensitive to? Both Ilford and Kodak have spectral sensitivity curves for their papers in their respective sites. Guillermo
Re: [pinhole-discussion] increased sharpness?
- Original Message - From: "Jim Kosinski" > in the formulas used to determine the optimal pinhole > diameter for a given focal distance the wavelength of green > light seems to be used because it's in the center of the > visible spectrum... would it be possible to get more > sharpness with the same pinhole diameter by changing the > color of the light? for example, what if you used a blue bulb > to illuminate the subject or put a color filter over the > pinhole? (assuming black & white film/paper) Yes to all the ??? above. Would you really see a markedly difference in the results? Not quite sure. Guillermo
Re: [pinhole-discussion] filters with pinholes
- Original Message - From: "Shannon Stoney" > > > How do you put a filter in front of the pinhole? With tape? If the size of your camera allows it, you could glue a step-up filter right in front of the camera (centered on the pinhole, of course). This is my wooden 8x10 with such an arrangement: http://members.rogers.com/penate/camera/filter.JPG Guillermo
Re: [pinhole-discussion] WPPD winding down!
- Original Message - From: > How do we access these Emil addresses? I can't seem to find them. Is this a > browser thing? Or am I looking in the wrong place. The artist's email address is right at the foot of the image, depending your screen resolution, you may have to scroll down the page. The email IS NOT CLICKABLE and IS NOT CUT/PASTE-able, this is on purpose (thanks Gregg!) so those programs that collect emails, won't be able to do what they do. The price to pay for that security feature (very small IMO) is that you will have to write the email address by yourself when sending emails to artists. Guillermo
Re: [pinhole-discussion] Cutting oatmeal box
- Original Message - From: "Bill Leigh" To: Sent: Friday, May 24, 2002 9:10 AM Subject: Re: [pinhole-discussion] Cutting oatmeal box > I have a Dremel tool that I got from my father. I've > been looking into using it for drilling a clean hole. > I just purchased a set of drill bits (sizes 61-80) for > a Dremel tools. When I went to use it, I found that > the chuck (or collett or whatever) did not go small > emough to hold the small drills, so I am looking at > buying a new chuck that can take the drills. The > smallest bit goes down to 0.013" You may want to buy a drill press stand for your dremel, it would make drilling the holes easier. I have that configuration and although I don't use it for pinhole making, I have used it in the past and it works (sort of). Just have in mind the hole may not be exactly the size of the drill and will have lots of burrs around them. Guillermo
Re: [pinhole-discussion] used enlargers
- Original Message - From: "Eric S. Theise" > Are there any 4 x 5 enlargers that will handle the full negative or do I > need to go to a larger size? Yes, a 5x7 would do what you want. A cheap option, if you can find one, is an old 5x7 Elwood Guillermo
Fw: [pinhole-discussion] focal plane shutter theory
I was reading my own post and noticed a mistake when converting inches to millimeters. I used a factor of 24.5 when in fact an inch is equal to 25.4 millimeters. The time to move across I talked about, therefore, should be: Time to move across film: (5 x 25.4) / 120 = 1.058333 seconds Not a big difference, but if NASA failed a mission to Mars because a conversion error, I don't want you to miss your exposure due to my conversion mistake :-) Guillermo > Let me think in "written voice" here: > > Since the film will be stationary, if we draw a very thin line on the film > (parallel to the shutter's slit), when the slit is moving accross the film it > will see that thin line passing by, the amount of time it takes that line to go > from one end of the slit to the other will be the exposure time. Exposure > time, therefore should be given by: > > Exposure time = slit width / speed of shutter moving across the film > > for instance: If you want an exposure time of 1/60 seconds and you have a slit > 2mm wide, you FP shutter should move this fast accross the film: > > FP shutter speed = Slit width / Exposure time > FP shutter speed = 2 / (1/60) = 120 mm/second > If the film is 4x5 (landscape), the FP shutter should take this long to move > accross the 5" length of the film: > > Time to move accross film: (5 x 24.5) / 120 = 1.0208333 seconds > > Thinking over !! > > Guillermo
Re: [pinhole-discussion] focal plane shutter theory
- Original Message - From: "Uptown Gallery" > This may be off topic, but the breadth of knowledge within this group may > provide me an answer (off list , if necessary). > > I would like to understand (actually, analyze) the operation of a focal > plane shutter, for the purpose of building one for sheet film. I want to get > a grasp on calculating exposure duration as a function of slit width and > linear speed, I guess (or direction to what I should be thinking about). Let me thin in "written voice" here: Since the film will be stationary, if we draw a very thin line on the film (parallel to the shutter's slit), when the slit is moving accross the film it will see that thin line passing by, the amount of time it takes that line to go from one end of the slit to the other will be the exposure time. Exposure time, therefore should be given by: Exposure time = slit width / speed of shutter moving across the film for instance: If you want an exposure time of 1/60 seconds and you have a slit 2mm wide, you FP shutter should move this fast accross the film: FP shutter speed = Slit width / Exposure time FP shutter speed = 2 / (1/60) = 120 mm/second If the film is 4x5 (landscape), the FP shutter should take this long to move accross the 5" length of the film: Time to move accross film: (5 x 24.5) / 120 = 1.0208333 seconds Thinking over !! Guillermo
Re: [pinhole-discussion] speed of paper versus film
- Original Message - From: > I'm struggling to understand the relationship between film and photographic > paper. Specifically, calculating exposures, etc. > > Where film may be considered ASA 100, paper may be considered P100. > > Obviously, it's not the same 100...but what's the relationship? Papers have 2 ISO parameters associated with them, ISO R and ISO P. The former has to do with the density range a paper or combination paper+filter is capable of. The latter is the speed of the paper. Ilford MGIV, for instance, has a speed of ISO P500 when unfiltered. As for the relationship, take the 500 divide it by 100 and you will get a rough estimate of the paper's speed when used as "FILM". Using that relationship we find that MGIV has a "film" speed of ISO-5. If you do a search of this list messages, you'll find that ISO-6 is a very common used value, ISO-5 or 6, close enough, IMO. If you use, let's say, a #0 filter, the ISO P speed becomes ISO P200, so your paper will behave, approximately, as "film" ISO-2 (I'd approximate that to ISO-3, BTW). Once you know the "film" speed of your paper and if you know the f/stop of your pinhole camera, calculating exposure is business as usual, with the exception of reciprocity, for which here is a table in a little article I wrote some time ago: http://members.rogers.com/penate/pinsize.htm Hope it helps, Guillermo
Re: [pinhole-discussion] pinhole is not about "sharpness"?
- Original Message - From: > Pinhole can be about sharpness, as well as softness... it's also about time, > and light, perspective, art, science, chance and fun! In the very far past I've been "nailed" in this list because of my interest on the scientific and mathematical approach to it, which has included the use of the so called "OPTIMUM" formula that is supposed to give us maximum sharpness, and the measuring of pinholes using microscopes. Now, you are "nailing" me because a statement I made was perceived as meaning I reject (for lack of a more suitable word) sharpness.Common, cut me some slack, will ya Michael !! :-) No pinhole image will ever be sharp, in the "lens photography" sense of the word. In that respect, the reason we practice pinhole obeys to "higher" causes, higher than "sharpness". Your reasons may or may not be the same as my reasons and even if they were the same, their order of importance could be different between yours and mine. Now, the above does not limit some of us (yes, I am one of those, believe it or not!) to want to get as "sharp" pinhole images as we can get, either sometimes or all the time. Science has never failed me, hence my advice to use the "scientific formulation" as the point from which deviate (or not!). Guillermo
Re: [pinhole-discussion] Optimal pinhole size question - theoretical & practical
- Original Message - From: "Tom Harvey" > It's the "very, very" that I wonder about. > I believe that Zernike Au has said that he used the smaller aperture > because tested out sharper. > Aside from lengthening exposure times, would using small size > pinholes on cameras with focal lengths of twice the "optimal" > focal length be any less sharp? Tom, All optimum pinhole formulas, starting with Lord Rayleigh's (1891) to the most modern one, like the one in M.Young's article foound at PV site, can be expressed as: Diameter = SQRT( K * F * Lambda ) That constant K has taken many values, some based on analitical reasons, some based on experimental reasons. You implicitly mentioned 2 values, the one in Renner's book, which BTW is congruent with modern formulations and Zernike's, which you mention to have read was found experimentally and gives way smaller diameters than the modern scientific formulation. I know of another experimental value, that found by C.Patton, which oddly enough, gives larger diameters. So there you have it, science says something and 2 pinholers have found experimentally that a larger hole produces better resolution (Patton) and the other (Zernike) than a smaller hole produces better results. I have to mention that Patton's value doesn't deviate drastically away from the "scientific formulation" as Zernike's does. Since pinhole is not about "sharpness", use any pinhole size for a particular distance pinhole-film, but I suggest you use what I call the "scientific formulation" as the starting point from which deviate. Guillermo
Re: [pinhole-discussion] Film transport system for 120 film
- Original Message - From: "Maria Grant" > Were can I buy a film transport system for 120 film? I hope I'm using the > correct terminology. > I've seen cameras made from coffee and tea containers with film > transports,but can't seem > to find this item,would I have to find a old 120 camera and use its system? > Can I us the transport > from a cheap plastic camera? Thanks in advance. I know which coffee/tea cameras you mean, I think the guy is Italian, BTW. I emailed him some time ago and he said, very politely I must say, he doesn't sell film winding mechanisms or ready made cameras. I think you could adapt the mechanisms you mention, it'll be a matter of finding the right coffee/tea container for it, but it should be doable. Guillermo
Re: [pinhole-discussion] Pinhole Day Questions
- Original Message - From: "Joao Ribeiro" > I have just had my pinhole day film returned from the lab. > I am now in the process of choosing an image and uploading it. How should I > proceed > for the uploading? > Thanks in advance, > I'm looking forward to see the pictures made by you that day. Joao, Just go here http://www.pinholeday.org/participate/submit.php Good to "hear" you again! Guillermo
Re: [pinhole-discussion] Not on Subject
- Original Message - From: "James Kellar" > I know this is not on the subject of pinhole or even photography, but I > just couldn't help myself. Goto > http://207.67.219.101/objective/propaganda.html, and then scroll down to > Apple Macintosh: > This is kind of funny and scary all at the same time. I knew I shouldn't buy a Mac, now I know why. Many thanks for the link James. Guillermo :-)
Re: [pinhole-discussion] viewfinder
- Original Message - From: "Joe Rollins" > I made a viewfinder by taking a exposure from a known distance from an > object, & developing. I then returned to the scene, stood the same > distance and cut a template out of cardstock to match the photograph. I then > cut a viewfinder out of heavy plastic using the template. > Very elementary, perhaps, but it seems to give me an idea of the intended > scene if the viewfinder is held the same distance from the eye. - Original Message - From: "Jeff Dilcher" > I have an even simpler solution. I have a small rectangle with > a 4x5 inch whole cut in it. It looks like a little frame. I hold this > up to my eye, and, voila, viewfinder! I also use a piece of cardboard with a 4x5 cut and a shoe lace attached to the cardboard, the shoe lace has knots at distances corresponding to focal lengths useful to me (75mm, 90mm, 135mm, 150mm and 240mm). I consider the above a composing aid and not a viewfinder. When using glass lenses, you could easily aim your camera to match the image you "saw" with your composing aid, you have the aid of the GG (functioning as viewfinder). For pinhole, the aiming of the camera would require some more help, like using GG+extra big pinhole lens, guide lines at the sides and top of camera box, wire/peephole frame matching the format in use or similar contraption. Guillermo
Re: [pinhole-discussion] Re: [pinhole-discussion]ground glass orientation
- Original Message - From: "ragowaring" To: Sent: Monday, April 22, 2002 8:17 AM Subject: [pinhole-discussion] Re: [pinhole-discussion]ground glass orientation > I am building a pinhole field camera with ground glass viewing screen. > Can anyone tell me which way round the ground glass surface faces. Does it > face front towards the pinhole (lens) or the back of the camera? Alexis, It really doesn't matter for pinhole. It only matters when using glass lenses, where the distance lens to ground side of the GG must be exactly the distance between lens to film. Nevertheless, I'd put the smooth side facing you. While you are at it, go to your nearest office supply store and buy a fresnel lens, they sell them a reading aids, cut a piece (from the center) equal to the size of your GG and mount it either in front or at the back of the GG, it will make your GG brighter. Guillermo
Re: [pinhole-discussion] Ultraviolet Light Pinhole Camera Project
- Original Message - From: "Adam Leiferman" > First I shone the UV laser on a front-surface convex mirror. > I then made "pinhole lenses" specifically constructed to create the > best images for the wavelength of light that I was using. >The pinhole's size was found through a formula that is available at the site > http://www.???/resources/articles/Young/. > The photograph taken with UV light was slightly sharper and clearer than the > photographs taken with red light. The reason is that the small wavelength > of the UV light causes less image blurring due to diffraction. To be sure > that the formula I used for the pinhole size was correct, I then made > pinhole lenses that were slightly smaller and slightly larger than the > optimal size predicted by theory. I took pictures with each and the results > agreed with the equations. The smaller-than-optimal pinhole caused the photo > to be slightly diffracted and the larger-than-optimal pinhole caused the > photo to be a little blurrier due to the increased hole size. Adam, Many thanks for lettings us know of your tests. There is a number of us interested not only in the aesthetics of pinhole photography but also in the science behind it. These kind of things are interesting and exciting for us (for me, anyway). The article you mentioned above, from which you took the formula for optimum pinhole size gives a formula and a approximated one, the latter being: S^2=lambda*F and the former: S^2=0.61*lambda*F. You took images using smaller-than and larger-than the optimum size, my question is: which formula did you use to find your optimum size? Thanks again, Guillermo
Re: [pinhole-discussion] darkrooms in Toronto
Liav, Check the darkrooms at Gallery44 in downtown Toronto, here is their URL: http://www.gallery44.org Guillermo - Original Message - From: "Liav Koren" To: Sent: Friday, April 19, 2002 6:01 PM Subject: [pinhole-discussion] darkrooms in Toronto > This isn't really a pinhole question; sorry. I'm looking around for a > darkroom to work in over the summer, until school starts again. Does > anyone have any recommendations for commercial darkrooms in Toronto (ie, > a place where I can go in and print, not a place that will print for me). > I'm in North York, but anywhere accessible from TTC is good.
Re: [pinhole-discussion] best viewfinders for close-up work
- Original Message - From: "Sarah Heidt" > > My younger brother does woodworking and has generously offered to build me a > large format pinhole camera. He even bought a set of micro drills for his > Dremel (are these small enough, I don't know!) Nothing like the love of a brother! As for the micro drills, they come in "wire gage sizes", here is a table: http://www.labenson.com/jobbers%20drills%20hss%20wire The "Decimal Dia" is the diameter in inches, you need that to calculate the focal length (distance pinhole to film) the holes made by the drills are "optimum" for. To find the focal length, just divide the drill diameter by 0.0073 and multiply the result by itself, that will give you the focal length in inches. I have seen specs for microdrill bits of up to #97 wire gage size, the table above only has up to #80, which is good for about 90mm focal length, a good focal length for a very wide angle 8x10 camera, I'd say. > All I have to do is give him the plans. (Don't give me grief about not building > it for myself--I'm a busy mom of two little girls, and shy of power tools...) Oh, the joys of parenthood! > I am not sure whether to > go 4x5 or 8x10. I don't have film holders. So should I purchase a wooden > film holder first on Ebay and then have him build the camera to accomodate > it? If you don't have a 4x5 enlarger (bro could build one too I guess :-) I'd recommend to go with an 8x10, you can contact print the negatives and have a nice size result. Yes, buy the holder first, it'll help your brother. > I have the book "Primitive Photography" by Alan Greene that shows very > detailed plans for making a large format camera (with lens!) and I was > thinking of giving the book to him and letting him use that as a guide. Any > other ideas or plans that are online I could send to him? Give him the book, tell him the most important part of the camera is the back. Show him also Bender's pinhole page, so he gets some additional ideas. Here is the site: http://www.benderphoto.com/pincam.htm Here is an excellent view of a good back design: http://www.enteric.org/810/images/17.jpg Hope it helps, Guillermo
[pinhole-discussion] OT - PBS Documentary on AA
Fellow pinholers, This coming April 21 at 9pm, PBS will be presenting "Ansel Adams: a documentary film". Check: http://www.pbs.org/wgbh/amex/ansel/ Guillermo
Re: [pinhole-discussion] The Wyndham Montreal Hotel Giant Pinhole Camera Project
- Original Message - From: "Guy Glorieux" > > There are no reciprocity failure charts for paper, but it is just as > real as for film. So I'll have to make some tests before next week but > I expect to end up with an exposure time of maybe 8-12 hrs. Guy, I have a reciprocity table for paper in my page http://members.rogers.com/penate/pinsize.htm it only gives you corrections for up to 20 minutes, but I just rapidly extrapolated some other values I hope are of some use for you as "starting point". Here they are: For 30' multiply time by 7 for a total of 3 1/2 hrs For 1 hr multiply time by 9.5 for a total 9 1/2 hrs For 1.5 hrs multiply time by 11.5 for a total 17 1/4 hrs For 2 hrs multiply time by 13 for a total 26 hrs For 2.5 hrs multiply time by 14 for a total 35 hrs For 3 hrs multiply time by 15.5 for a total 47 hrs For 6 hrs multiply time by 21.5 for a total 129 hrs > The plan is to calculate the focal length/F-stop based on the weather > outside so as to be able to open the shutter at 00:00hr on Sunday April > 28 and to let the exposure run until 24:00hr. That is a wise decision! Wish I could be there! :-( Best of luck, Guy and your fellow photographers. Guillermo
Re: [pinhole-discussion] business on list
- Original Message - From: "Ray Esposito" > Jim - no offense taken. I should have known better. The excitement > got the better of me. Apologies to all. Jim is correct. Sure he is, that's why his yesterday message to you should have been sent directly to you and not to the list, had Jim done that, your replay would have gone directly to Jim and not to the list. BTW, I don't mind "commercials" from list members. Like when someone is auctioning something at eBay or when Jim, tell us about a new pinhole camera he is announcing or even if Zernike were to tell us about a new product, too. I take that as information rather than as advertising. Guillermo
Re: [pinhole-discussion] fixing in tubes and trays
- Original Message - From: "shannon stoney" > Does it have to be absolutely, plumb thick dark when you finish > fixing in the tray after a short fix in the tubes? I don't have a > completely dark ventilated place yet. No, I turn on my safelights after 1/2 the total fixing time with no ill effect. Reading this instructions for the BTZS tubes make help you http://makeashorterlink.com/?Y1FE31FA Guillermo
Re: [pinhole-discussion] Film Development
- Original Message - From: "Richard Heather" > neither of us are right. 24x36x36 =31,104mm2 > 8"(x2.5)x 10"(2.5) = 50,000 mm2 > Richard Heather Richard, Remember that the actual length of film allows for 36 frames + leading and trailing portions of film (probably the equivalent to 5 to 6 extra frames). In addition, the width of the film is not 24mm but 35mm and there are 2mm separating each frame, also. All that, minus the area for the sprocket holes. So w/o accounting for the trailing and leading portions of film and the sprocket holes, the area would be: 35 x 38 x 36 = 47,880 mm2 Guillermo
Re: [pinhole-discussion] my first photo
- Original Message - From: "Matti Koskinen" > I have Corel PhotoPaint) I use only Linux and Gimp, win98 crashes almost > every time I try to scan. You're doing the plugging but not the "praying", obviously. Remember W98 is plug and PRAY! > I placed a #0 filter behind my camera and took photos. They're still > drying, but looks like they are really much better with tonality than > without the filter. Filter kit I have is Ilford Multigrade. The tests I > made showed that in a clear sunshine without filter 30 sec. was enough > but using filter 2 mins. had to be exposed. Any reason for this long > exposure? The guide in the filter box says that when enlargening using > #0 filter has no effect in exposure time. 2 reasons: -Those filters are made to filter tungsten light and you are using them to filter daylight. That may account for the increased time. -Since the use of the filter increases the uncorrected exposure time, reciprocity corrections become a bit drastic and increases the reciprocity corrected time even more. > My camera is 4x5 from an article of Popular Woodwork, searching the web > gave this link, but I printed the article so I don't have the url anymore. > Focal length is 120 mm. Here is the link: http://www.popularwoodworking.com/features/fea.asp?id=1048 Guillermo
Re: [pinhole-discussion] paper negative tricks
- Original Message - From: "Tim Rawling" > The other cool thing about having a sealed pinhole camera is that you can > fill the camera with water before you expose the image to increase the field > of view (due to the diffraction of light at the air/water interface) Not that ot matters too much, but the phenomenon is refraction not diffraction.
Re: [pinhole-discussion] paper neg.
- Original Message - From: > Paper is not better - it is just different. Paper is not worst - it is just different. Guillermo
Re: [pinhole-discussion] Developing 8x10 sheet film
- Original Message - From: "Greg Newberry" > Well, I've been going along happy as a clam designing my 8x10 pinhole camera > when all of a sudden I realized that if I shoot sheet film, I'm going to > have to develop it! So I know you can do it in a tray, and I've seen the > sheet film holders that stand up vertically in a box of developer, but what > is the best way? It seems that agitation may be an issue in a tray, but a > box full of developer and the vertical film holders would use a lot of > developer, plus you would need three. Then washing them? Is this the current > best technique? I develop 8x10 in trays, but you could use a simple hybrid technique of trays+drum. Buy a piece of ABS 4" diameter pipe, film goes inside pipe and then pipe in the tray. Agitation is achieved by rotating/rolling the pipe. You could also buy one of those 8x10 print drums, they are constantly listed at eBay, with or w/o motor base. Guillermo
Re: [pinhole-discussion] paper negative tricks
- Original Message - From: "Andy Schmitt" > or build a developing tube or 2..then you just load & roll...sort of.. 8o) > andy That's another possibility. Here is a link to a design I have read is effective: http://people.smu.edu/rmonagha/brontube.html Guillermo
Re: [pinhole-discussion] paper negative tricks
You are in Suomi, isn't that right Matti? I visited Turku (University of Turku) and Helsinki, way back in the spring of 1978, Finish people were very friendly and kind to us every where we went and stayed. Anyway, there are daylight tanks that allow you to process 4x5 film without a darkroom, all you need is a changing bag to load the film in the tank. I use a COMBI PLAN 4x5 TANK ( http://www.hpmarketingcorp.com/hp_combi.html ), it is made in Sverige, so I'd imaging stores in Helsinki or in Stockholm, carry it. There are other tanks like the Yanki and couple of Jobo ones, but I haven't use them, myself. Guillermo - Original Message - From: "Matti Koskinen" > yes, film would be an ideal solution, but to develop it is the problem. > It's fairly easy to develop a paper negative in my minimal darkroom (a > closet which is the only place I can darken totally) but to develop a > film, as the only way would be to develop sheet film is in trays, and I > think that would just be a mess. First thing would be to put the film > first in the stop bath or fixer. But having a safelight makes things > little bit easier. Litho film is one thing I'm going to give a try, but > it's also high-contrast. And pinhole day is coming soon...
Re: [pinhole-discussion] paper negative tricks
- Original Message - From: "Matti Koskinen" > > I finally got my wooden 4x5 camera lightproof and taken few test shots > using paper negatives. > Problem with paper negative seems to be the total lack of details in the > sky, getting the sky with some clouds make the print look more "real". One way is to use film instead of paper and also use a red filter. Guillermo
Re: [pinhole-discussion] Brand New Pinhole User Questions
- Original Message - From: "Katharine Thayer" > > Just remember, if you're using an 8x10 filmholder, that 8x10 paper is > bigger than 8x10 film, and you'll need to shave a little off each side > of the paper to make it slide into the holder smoothly. > Katharine Thayer Try it before you shave, my 8x10 holders take 8x10 paper "sans" shaving.
Re: [pinhole-discussion] Brand New Pinhole User Questions
- Original Message - From: "Greg Newberry" > have been taking and developing the film and I'm hooked! I want to build a > camera to shoot 8x10. I've seen some references to using Ilford multi-grade > paper as the film and then contact printing it. Would someone explain the > basics of this method to me, or point me to a web site? http://makeashorterlink.com/?X1CB314A > I am planning on > building a camera around an 8x10 film holder to use either film or paper. Is > single weight paper the best because it's thinner? Yes.
Re: [pinhole-discussion] human subjects
- Original Message - From: "Joe Rollins" > GlacierI am trying to build a pinhole camera to use to take photos of human > subjects. I need to get the time down to under 10 or 15 seconds. I shoot > with Ilford MGIV. What focal length and diameter pinhole would be sugested. > Joe Rollins I am sorry to say, that this is a case for which a little bit of math comes in handy. As Thom said, you don't give too many details of your shooting, so I am going to make some assumptions. I am going to assume you want to use an "optimum" size of pinhole and that you will be shooting with a light level equivalent to f/16 @ 1/6 secs, that BTW is the indicated exposure for shooting outdoors under open skies/bright sunny day, otherwise known as "sunny16 rule". I am also assuming you rate MGIV as ISO-6. Here is the analysis: As per reciprocity table for MGIV (see it in my paper "Determining Pinhole Size and Exposure " at http://members.rogers.com/penate/pinsize.htm ), for a 10 to 15 secs max exposure time you would need an uncorrected time of no greater than 8 secs. If existing light level calls for an exposure of f/16 @ 1/6 secs, we need to find an equivalent pair of exposure values for when the exposure time is 8 secs. The answer is f/128 @ 8 secs. Once you know the f/stop your pinhole camera must have, which is f/128, you can find the focal length for which when using an "optimal" pinhole size, you'd get an f/stop of f/128, you do that with this formula: Focal length in millimeters = (f/stop x f/stop) / 738 In your case, f/stop = f/128, so we have: Focal length in millimeters = ( 128 x 128 ) / 738 Focal length in millimeters = 16384 / 738 Focal length in millimeters = 22 mm Further explanations upon request. Guillermo
Re: [pinhole-discussion] Re: image circle relative to focal length/fstop
- Original Message - From: "Zernike Au" > If you want to control the circular image to 2' or 3" (the range is quite > big!), the main factor is > the thickness of the front panel of your camera that hold the pinhole and > where you mount the pinhole, and also the size of the opening of the front > panel. Sure, that's a way to restrict the size of the image circle. If you go that way, instead you may just want to make a circular cut out of opaque material, print the image with your enlarger then place this circular cut out in the center turn on the room lights some seconds, presto! you have your circular image! Photoshop would make it even easier/faster to achieve it. Not quite sure the aesthetics would be what Thom is looking for, tho, but as always, I may be wrong. Guillermo
Re: [pinhole-discussion] Ideas for finishing pinhole
Jeff, You could probably find Aluminum oxide at a science store or if there is one in your location, at a lapidary supplier. You could also use the rubbing paste auto painters use to polish cars after they have been painted. A better idea would probably be to thin the material by hammering with a ball hammer against a solid metal surface, like blacksmiths do. Aluminum is soft so there is no need for heating it, I believe. A better material than the brittle alu.pie is the aluminum of a pop can, sand the non printed side (first or last) as it has a plastic like coating. And finally, if you don't want to be thinning material, you could go to a automobile parts store and buy BRASS SHIM STOCK, they sell it in different thickness, you may want 0.001", 0.002" or 0.003", these guys call it 1 thou, 2 thou and 3 thou (thou as in thousand). 0.002" is generally the best thickness, IMO. not too thick that causes fast fall off, not too thin that is difficult to work with. Guillermo - Original Message - From: "Jeff" To: Sent: Tuesday, March 26, 2002 1:12 AM Subject: [pinhole-discussion] Ideas for finishing pinhole Hello, made my first pinhole from aluminum pie tin, but I need to thin the material some more. Sanded with 600 wet/dry paper, but have a better idea: using fine grit and a marble, a "concave" surface could be formed... hopefully at it's thinnest near the pinhole. Anyone tried similar method? I'm trying to find a source for the grit (like is used to grind glass) and hopefully don't have to mail order. Any suggestions for where to find this stuff locally?
Re: [pinhole-discussion] image circle relative to focal length/fstop
- Original Message - From: "Thom Mitchell" > Would then a thick material create a smaller circle with the same image > quality (or not) as a thinner material? These may be simple questions but I > want to be able to control the size of my image circle, either through > pinhole size or focal length. It now sounds like material thickness could be > a 3rd variable to play with, and possibly the most productive. Any other > advice out there? Thanks for the responses so far. Thom The 2 variables you have are distance pinhole to film/paper and thickness of the pinhole material. The distance or focal length will cause a slow light fall off, as given by an esoteric physical/optical law, sort of. A pinhole made on a thick material would cause a very fast, almost sudden fall off, due to vignetting (have the impression this is what you're looking for, but I may be wrong). As far as specific examples, calculation would have to be made to find them out or to find possible rules of thumb, but since the requirement is no math, trial and errors would have to be made to find a possible relation between thickness of material and fall-off. The relation between focal length and fall-off was already answered by Tom in a previous message. There is a 3rd variable and is the ratio pinhole diameter versus thickness of material, but let's not go there 'cause it would complicate and augment the empirical tests. Guillermo
Re: [pinhole-discussion] image circle relative to focal length/fstop
But if your aim, Thom, is to have a circular image in the middle of your paper/film format, the bellow mentioned rule will not work for you, in such a case you should perhaps assume a 5 times the focal length or even more. Use also thick material to make your pinhole. Guillermo PS: it was somewhat hard to answer this nature of question without recurring to use "derivative calculus" which BTW, I thought it was called trigonometry, taught in grade 8 to me. My friend Juan use to say: "why are we learning this stuff we would never use", he was probably right ;-) - Original Message - From: "Tom Miller" > The rule of thumb is that, on a flat film plane, the circle will be > 3.5 times the focal length. So, if the focal length is 1" the circle > will be 3.5", if the focal length is 2" the circle will be 7", and so > on. The f-stop doesn't really matter for this rule of thumb. > > - Original Message - > From: "Thom Mitchell" > How can I quickly determine the size of the image circle for a given > focal length and f/stop. I want to be able to keep an image circle > from getting too big, i.e. I want it to be 2' or 3''. Any quick help > would be appreciated as would simple rules of thumb as opposed to some > of the derivative calculus I sometimes see. Thanks for your help in > advance. Thom
Re: [pinhole-discussion] Slightly Off Topic
- Original Message - From: "Jim Kosinski" > http://directory.google.com/Top/Science/Astronomy/Amateur/Astr > ophotography_and_CCD_Imaging/ > > Jim K Jim, your link broke down, this happens to me all the time. I have found this site in which you paste a long link and it will generate a short one that will automatically sent you to the long one, I find it very useful. The site is http://makeashorterlink.com/ For instance, the above link you gave, becomes this very short one: http://makeashorterlink.com/?T1102059 Just an FYI. Guillermo
Re: [pinhole-discussion] Slightly Off Topic
- Original Message - From: "Tedd McHenry" > I apologize for being slighty off topic. I'm not a pinhole photographer, but > I'm working on a science-fiction story that involves pinhole astronomy. I'm > looking for good sources of information for the novice that explain the theory > of pinhole cameras or telescopes. I don't mind getting into the physics ofit. > In fact, that's exactly what I want. Can anyone recommend any books, websites, > or other sources of information that might help me? http://users.erols.com/njastro/barry/bar-page/pinhole.htm http://www.???/resources/articles/Young/
