2015-033 Alchemy

Pinhole cameras are more alchemy than science.

I went prowling on-line today for pinhole exposure calculators, having had a series of badly under and overexposed shots. By rights one ought to be able to compute the f-stop by dividing the effective focal length--the distance from the pinhole to the film--by the diameter of the pinhole and work from there. Unfortunately, the relationships are not linear as exposure times get past a second or two and one has to throw in a "reciprocity-failure" multiplier for longer exposures. Fudge factors rule!

I printed the charts and tucked them into my little book, which will now have to do double duty as journal and exposure record. It will henceforth be the alchemist's journal.

I found a reciprocity fudge factor chart at www.instructables.com/id/Desig…

I found an exposure calculator at www.mrpinhole.com/exposure.php

Today's prompt from writealm.com/february-prompts/