Developing Sheet Film at N - 20%greenspun.com : LUSENET : Large format photography : One Thread
I am still trying to figure out bits and pieces of the Zone system and ran into an interesting situation. I exposed a piece of Tri-X at f64 for 35 seconds. Then adding in extra time for reciprocity failure, came up with a final exposure of f64 for 130 seconds. According to a class I took, when compensating this much for reciprocity failure, I should decrease my development time by 20% (hence N - 20%). When my N development time is 5.5 minutes, then N-20% is 4.4 minutes. Everything I've read and heard says that you shoud never develop for less than 5 minutes.
In a case like this, where the calculated development time is under 5 minutes, how should one compensate to bring up the development time to >= 5 minutes? Should one lower the temperature of the developing solution a couple of degrees?
Thanks for all ideas/suggestions, Robert
-- Robert Ruderman (email@example.com), April 30, 1999
First, the minimum developing time (for complete even development without streaks, uneven areas, etc.) depends on the method. I tray develop and routinely develop Tri-X and T-Max for 4.5 minutes with excellent results. Other avenues to explore to reach an "N-20%": dilute developer solutions, lower temperature and, of course, a different developer entirely. With the these last you must first find the time for N and then subtract your 20%. Experiment, experiment and you'll have no trouble finding the answer. Hope this helps. ;^D>
-- Doremus Scudder (ScudderLandreth@compuserve.com), April 30, 1999.
I'd be inclined to dilute the developer more rather than go to shorter times.
-- John Hicks / John's Camera Shop (firstname.lastname@example.org), April 30, 1999.
I've got very good experiences with varying dilutions with HC110 to control contrast. I agree that development should not be too short or too long. I prefer - intuitively - between 6 - 8 minutes, otherwise I'll choose another dilution. Changing temperature is not my choice, it's more error-prone. Recently I use Rodinal, but varying dilutions here does not seem that predictable as with HC110 (so far, which is not very far yet).
-- Lot (email@example.com), May 02, 1999.