I have made all my zone system tests of tmax100 4x5 using dilutions of 1:15 (fro m stock) for n, n-1, n-2 but when it came to n-3, the development time became ve ry short (under 5 minutes) so i changed the dilution to 1:30. the results are ok but development time is exceedingly long. is there a formula to compute develop ment time for various dilutions?
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