So, I would like to try this test with my medium format film... However, my only controllable light source is my condenser enlarger. Is there a way to determine how long my exposure time (i.e., time the enlarger is switched on) for contact printing for a given enlarger height and lens aperture? I have a spot meter and a gray card, and for some reason that seems like all I should really need to determine a length of time for which to expose the film. But I'm clueless about how to determine a contact exposure time given a light meter's reading of f-stop and shutter speed.