Developing Sheet Film at N - 20%

[Robert Ruderman]

Hi,

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. Th en adding in extra time for reciprocity failure, came up with a final exposure o f 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, h ow should one compensate to bring up the development time to >= 5 minutes? Shou ld one lower the temperature of the developing solution a couple of degrees?

Thanks for all ideas/suggestions, Robert

[Doremus Scudder]

First, the minimum developing time (for complete even development without streak s, uneven areas, etc.) depends on the method. I tray develop and routinely devel op Tri-X and T-Max for 4.5 minutes with excellent results. Other avenues to expl ore to reach an "N-20%": dilute developer solutions, lower temperature and, of c ourse, a different developer entirely. With the these last you must first find t he time for N and then subtract your 20%. Experiment, experiment and you'll have no trouble finding the answer. Hope this helps. ;^D>

[John Hicks]

I'd be inclined to dilute the developer more rather than go to shorter times.

[Lot Wouda]

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).