I've recently started shooting some Efke PL25 in 11x14, the lighting conditions I'm shooting in routinely put me in 4, 6 and 8 minute exposer times. Part of the long exposer times I'm experiencing is because of depth of field issues in ULF, I usually have to stop down to f90 or f64 minimum. J&C list reciprocity times as follows: Efke PL25/50 Suggested Reciprocity Adjustments to 1/2 second - 0 stop 1 second - 1/3 stop 10 seconds - 2/3 stop 100 seconds -*1.5 stops At a 4 minute exposer I'm already at 240 seconds and going down probably more than three stops (f45) which does not help me. I would much rather extend my exposer time than mess with my already small f-stop scale. Is there any way to accurately figure out extended reciprocity times from the above tech info provided by J&C?