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Photography Forums
Pin-Head
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Date Posted:
Oct/20/2007 6:44 PM
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Hello to anyone with metering experinece with pinhole cameras!~ ( And everyone ELSE, TOO!)
I have a custom made pinhole camera. The focal length is 40mm and the f stop is 158 -pinhole( !?...That is how it was listed) . SO!....Using a hand held meter ( any suggestions, too, on what kind to get!?) how do I go about estimating what are normally much longer exposure times than with standard cameras?!~
Your help is most graciously appreciated!~
Sincerely, Ken
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swanseamale47
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Date Posted:
Oct/21/2007 6:07 AM
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The answer depends on the "speed" of your film/paper. My limited experience of pinhole cameras (totally home made using 5x7 paper) gave exposure times between about 30 seconds and a few minutes, but I honestly couldn't remember what size the pinhole was now, so not much help I'm afraid. Wayne
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BobF
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Date Posted:
Oct/21/2007 9:23 AM
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Set your meter for a specific f/stop, say f8, meter the scene at that aperture setting with the proper ISO speed then simply multiply the shutter speed you get by the factor of your pinhole (i.e., the number of stops it is away from f8). So,
f11
f16
f22
f32
f45
f64
f90
f128
Your 158 is somewhere in between f128 and the next value, about half way. So if you get roughly 8.5 stops. The factor for the shutter speed multiple would be 2^8.5 (which is 362). Multiply that number by the meter shutter speed in all situations and you have your base exposure. The other thing you need to take into account is reciprocity failure. The data sheet that comes with the film should help with that but typically those don't go as far as you need them to so there'll be some measure of trial and error. So if your base exposure is 1/8 at f8, your pinhole exposure will be .125 x 362 which is 45 seconds. You then need to factor in reciprocity failure from there.
As far as what type of light meter, a simple, inexpensive meter will do the trick. Check KEH.com to see if they have any used ones that may be a bit less expensive.
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RF Photography
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Pin-Head
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Date Posted:
Nov/04/2007 6:03 PM
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Hello!~
Thank you so VERY much for taking the time to explain some exposure info with pinhole photography!~ Since my cranium appears to be pretty small when it comes to this NUMBER technique, I get a little DAFT! Hopefully I will one day get to the instinctual level. There will be a LOT of film, between here and THERE!~
Gratefully yours~
Ken
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