Quote Originally Posted by edcculus View Post
Ok, one more question re the actual pinhole. If I use an enlarger to measure the hole...how exactly do I calculate or figure out the enlargement? Sorry if that is such a stupid question.
1) Take a piece of clear film and make a mark of 1 cm on it with a pen like this |----|.
2) Put it in your enlarger and project the line. Now measure the line on the base board (lets say 8 cm).
3) Calculate the enlarging factor for this line: 1 cm/8 cm = 1/8 or (0.125).
4) Put the pinhole in your enlarger and measure the diameter of the projected circle (lets say 1.2 cm).
5) Multiply this factor with the measured diameter: 1/8 x 1.2 cm = 0.15 cm.

Now you know your pinhole diameter is 0.15 cm.

* it doesn't matter how high you turn your enlarger: but use the same hight for both measurements!
* it also works with inches ;-)