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#1
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how long is the exposure?!?!?!?!?!?
HI, i was wondering about how long my exposure time should be for a
quaker oatmeal box pinhole camera. the hole is about 1/8 inches and i'm using black and white paper. pleeez help me out thanks |
#2
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how long is the exposure?!?!?!?!?!?
"max" wrote in message ups.com... HI, i was wondering about how long my exposure time should be for a quaker oatmeal box pinhole camera. the hole is about 1/8 inches and i'm using black and white paper. pleeez help me out thanks Since pin holes do not have a definite focal length the equivalent f stop is calculated from the distance the hole is from the image. A 1/8th inch hole is too large. A more reasonable size would be around 1/50th or 1/75th inch, very small. You can get some information from Kodak at: http://www.kodak.com/global/en/consu...leCanBox.shtml The instructions there talk about Kodak Kodabromide paper which has been discontinued. However, most variable contrast paper has a somewhere from the same to about half the speed when used without a filter. Another good site is: http://www.photo.net/learn/pinhole/pinhole Which has the formulas for calculating the optimum size of pinhole and its effective f stop. The pinhole size is not at all critical. Also, while an ideal pinhole should have no burrs around the edges the difference in practice is slight so a pinhole made by pushing a pin through some aluminum foil will work fine. If you use an exposure meter the effective speed of typical fast enlarging paper is around ISO-5. You will, of course, get a negative, but you can contact print to another sheet of paper to get a positive print. -- --- Richard Knoppow Los Angeles, CA, USA |
#3
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how long is the exposure?!?!?!?!?!?
In article . com,
"max" wrote: HI, i was wondering about how long my exposure time should be for a quaker oatmeal box pinhole camera. the hole is about 1/8 inches and i'm using black and white paper. pleeez help me out thanks 1/60 of a second for the white side of the paper, and 1/2 second for the Black side. -- Reality-Is finding that perfect picture and never looking back. www.gregblankphoto.com |
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