under exposed film

[Steve M Hostetter]

Hello,

How do I give a stop in development?

thx
steve

[Brian Ellis]

What do you mean by "give a stop?" If you mean how do you gain th equivalent of one more stop than normal, you develop to N+1, N being your normal time and +1 being the amount of additional development time needed to increase the highlight density by the equivalent of one more stop (e.g. move Zone VII to Zone VIII). You determine that time by testing. But in the absence of testing adding 15-20% to your normal time will get you in the ballpark.

[Steve M Hostetter]

Brian,

Thx, that's what I mean't I just never knew how to translate that to development

[chassis]

Not sure which film + developer you are using. The Kodak tech pub for Tri-X ASA 400 in small tanks indicates 1 minute longer development (about 10%) for a two stop push to ASA1600.

So for discussion's sake a one stop push is around 5% longer development time, with TX 400 using D-76 1:1 at 72 deg. F in small tanks.

Interestingly, the same tech pub indicates almost a 50% increase in development time for a two stop push to ASA 1250, if you are using TXP 320 in XTOL at 72 deg. F in rotary tubes. D-76 times are not listed for a two stop push with TXP 320.

[Steve M Hostetter]

I'm developing 11x14" separation negative film type 2 iso 40 .. I been treating it like efke 25 in regards to development in D76 1:1

[Jim Noel]

If you want to increase the density of the highlights onthe negative one stop, you need 40% more development. If you were using T-Max or similar, this would be only 20%.
However, no increase in development is gong to do anything to increase density (detail) in the shadows. You will begin to get some increase in the lower mid-tones, and the most in the upper highlights. Shadow density is determined by exposure and is only increased by a couple of special developers none of which are still available over the counter as far as I know.