When making a pinhole by means of a needle one usually know the pinholesize by the needle size used. I seem to recall that there is another way to do get to know the exact pinholesize but cannot remember the formula used. The method was described as follows. Mount the pinhole sheet in a slideframe, place it in a slideprojector. Then by measuring the distance from the pinhole in the slideframe and to the projector screen and the diameter of the projected pinhole on the screen, by means of a formula it was possible to find the exact pinhole size. Anybody out there that know which formula (s) to use??
Rune Tallaksen Norway
