TMax100 ; reciprocity characteristics

[fw]

Does anyone have a reliable guide as to the reciprocity corrections required for TMax100 for exposures > 1 second ; comments on both exposure compensation and d evelopment would be appreciated.

[scott jones]

Hi FW,

The Kodak web site has the short table for reciprocity failure which I suspect is written on your box, but here is the link: http://www.kodak.com/global/en/professional/support/techPubs/f32/f32b. shtml#1153016

There is no detailed curve like they have for Tri-X that I can find.

Scott

[David A. Goldfarb]

Kodak's guideline is no correction needed up to 10 seconds. Steve Simmons has a chart for TMX in _Using the View Camera_ which is somewhat more conservative, but TMX has such a wide tonal range and long straight curve that less compensation is needed than for traditional films.

[bob moulton]

Indicated actual Is 1 2

[bob moulton]

1 s=1 2s=2.5 4s=6 8s=11 15s=25 30s=54 60s=1:55 1m=1:55 2m=4:00 4M=8:30 8M=17:30 15M=36:00 30M=1H30M 60M=3H30M

Hope this guide helps. Bob

[ernie gec]

Bob:

I'm very interested in your adjusted figures. They don't correspond at all to the Kodak supplied data & I'm wondering what kind of testing underlies these numbers.

ernie

[Michael Kadillak]

Bobs numbers are on the money as they are nearly identical to my set compiled from Howard Bond (Jan/Feb 2001 Photo Techinques pg 54) and Bruce Barnbaum ("The Art Of Photography" Second Edition pg 80). Barnbaum feels that a N + 1/2 is the necessary adjustment. Considering the age old axiom that the answer can only be as accurate as the least accurate input, my objective is to get in the ballpark. Should entensive reciprocity be something that you encounter regularly in your photography, there is always the densitometer.....

The limited amount of correcting I have done for reciprocity using the factor table listed by Bob with these factors seems to be fine. Out of habit, I take anything Kodak says about these factors and the darkroom with a grain of salt.

[fw]

Bob - those factors are very helpful - what development adjustments do you make, if any? Regards

[Robb Reed]

Mike,

Is that N+1 or N+2? Or do you mean N + 5% (which would = N+1/2)

Thanks,

Robb Reed

[Michael Kadillak]

The reference to Barnbaums N + 1/2 associated with his reciprocity correction deserves further clarification. In essence, he is stating that because of the extended exposure, the net effect on the negative is an N + 1/2 with normal development. If you desire a N development, then you must give the negative a N - 1/2 to compensate for the contrast increased during the long exposure. Hope this helps.