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Pierre Robitaille
15-Jan-2002, 23:30
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?

Alec Jones
16-Jan-2002, 00:06
Check here: http://www.covingtoninnovations.com/hc110/

neil poulsen
16-Jan-2002, 07:22
Within an appropriate range, concentration is inversely proportional to development time. If one doubles the concentration, one must halve the development time to achieve the same effect. Below a minimum level of concentration, I suspect that this relationship no longer holds.

Scott Walton
16-Jan-2002, 12:59
You development times shouldn't be that long. Short with Dilution A, yes but with Dilution B (1:31) you should be in the 8-10 minute mark.

Charlie Stracl
16-Jan-2002, 14:57
Dilution B is 1:31 from consentrate, and 1:7 from stock. 1:15 from stock is half the concentration of dilution B. 1:30 from co

Are you certain you have enough developer that you aren't going into developer exhaustion?

Kodak gives capacity as 5 or 10 sheets per liter dilution B (first number is tank, second is tray processing) which gives 2.5 or 5 for "half B" and 1.25 or 2.5 for "quarter B" dilutions. These are 8x10 sheets.

My impression is that it is very difficult to get good results with such extreme contractions from modern film. If you don't have it, I suggest you get the book: Film Developing Cookbook.

Pierre Robitaille
16-Jan-2002, 18:15
I want to thank you guys for your quick answers. alec, the site you suggests contains a lot of useful info. neil, do you know what is that minimum level of concentration for hc110? scott, my normal time is 6 minutes at 68 degrees. charlie, that is a good advice and i always have to double check the capacity, especialy at greater dilutions. as for the capacity of contraction of modern films, tmax100 is very, very sensible to variations of development times and temperature. i always use rather large volumes of developper (at least 64 ounces) in a water jacket to keep constant temperature.