Bellows factor

Hi everyone

I have rigged up an "extension tube" for my Zero image
4X5 camera that puts the pinhole 32.5CM from the film
plane. The pinhole is designed for use at about 5.0CM.
I'm not worried about the "optimal pinhole" thing. I'm
confident this will create an image, just wondering
how much this distance is likely to force me to
lengthen my exposure time. I will be experimenting, of
course, but in the hope of not wasting too much film,
does anyone have a rule of thumb?

If I would expect a 2-second exposure outside in full
sunlight with a 5.0CM "focal length", for example,
what would be a theoretical equivalent at 32.5 CM?

Thanks

Colin

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Received on Thu Nov 29 17:43:30 2001