[pure-silver] Re: speed loss with perceptol
----- Original Message ----- From: <shannonstoney@xxxxxxxxxxxxxxx> 
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Wednesday, October 24, 2007 11:52 AM
Subject: [pure-silver] speed loss with perceptol
Hi, I'm out in west texas shooting FP4+ in very bright light. I'm thinking of trying Perceptol when I get back to my darkroom, but I read on the ilford site that there is some speed loss with perceptol. It didn't say how much. So, how should I adjust exposure? Today I shot it at ISO 100 instead of 125. 

I'm shooting roll film, not sheet film.

--shannon
Iford Perceptol and Kodak Microdol-X are identical or so nearly so it makes no difference. When used full strength to obtain the extra-fine-grain property the two lose about 3/4 stop of speed compared to D-76. I use either routinely for 35mm 100T-Max and generally shoot at about EI-50 but I also develop a bit less than the chart times. EI-100 should be fine if you are developing for diffusion enlarging. Note, both Kodak and Ilford give times for their developers diluted 1:3. At this dilution both become acutance developers with normal film speed and about the same grain as D-76. I prefer the extra fine grain of the full stength stuff. I find it makes a noticable difference in 35mm negatives but not so much for 120 because the negatives are so much larger they don't have the slightly gritty look that is common for 35mm negs. 

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 
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