Adding DIY extension tubes will give you a longer focal length…
The distance from the sensor to the pinhole determines the focal length of the lens, so it makes sense that if you want a longer focal length pinhole lens, you need to add an extension to the pinhole body cap.
Some inventive photographers have painted a toilet roll tube black inside, fixed that to a hollowed-out body cap, and placed the pinhole on the end.
Black plumbing parts also work well; the parts can be fixed together using dark glue or black silicon rubber. If you own a set of extension tubes, you can simply fit your pinhole body cap to them, as we have done.
We fixed our pinhole body cap to a 25mm extension tube, and also tried the 25mm tube stacked to a 12mm tube.
However, as the optimal size of pinhole is determined by the focal length, the size of the pinhole ideally needs to be larger, the further away from the camera it is.
Focal lengths in relation to pinhole sizes
45mm = 03.mm pinhole size at f/150
70mm = 0.4mm at f/175
95mm = 0.5mm at f/190
PAGE 1: How to make a digital pinhole camera
PAGE 2: How to make your digital pinhole telephoto
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Posted on Wednesday, January 16th, 2013 at 1:00 am under Photography Tips.
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