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Pat: At the risk of offending Jorge, he has it backwards. I'm assuming you are testing under the enlarger and since a film rated ASA 25 is 2 stops SLOWER than ASA 100, you need to INCREASE the exposure on a white card spot metered on the easel by 2 stops or EV 5.4. In some of Phil's original work, he suggested as follows-Ev 4 for TMX-100 exposed @ 1/5 sec. on the easel. EV 2(less exposure) on the easel for Tri-X 400. An important issue here also relates to your enlarger timer, namely- what is it, electronic or mechanical control. Remember that what you're really doing by exposing film via the enlarger ,is pumping energy into the silver emulsion to activate the silver compounds. If you have a mechanical timer controlling the enlarger, 1/5 sec is impossible. The best way to approach this problem is to use your LF lens on the enlarger and set the exposure at either 1/4 sec or 1/2 sec and see what f stop reads 5.4. Then do the test. ?'s, send me an E-mail. Didn't I answer this ? once before? Ben
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