I have made a few pinhole cameras over the years, mostly from modifying old roll film cameras. I have recently acquired a large film holder (8.5x15") and I want to build a wide angle box pinhole camera for it. My intention is to shoot x-ray film then make cyanotype prints.
So, I am having trouble calculating the focal length - I want it to be wide angle - about equivalent to a 24mm lens on 35mm film, and then the optimal pinhole diameter for that f/l, for the sharpest possible pinhole negatives. I will be making the pinhole out of very thin brass shim material.
I have tried a couple online pinhole calculators but am confused with the results.