Observation: I seem to get longer exposure times (1.5-2x) using this app (without accounting for reciprocity) than by using zero image's wheel or the pinhole designer charts. Am I using the program incorrectly, and is that somehow related to my question?
I've had the same problem. I' getting a lot of overexposure if I just use the app. So I gave up and use the scale that came with my ZI and light meter.