I received Barry Thornton's book "Edge of Darkness" for Christmas. One of the things he recommends is to reduce the rated film speed by half and develope it in diluted Perceptol. I intend to try this with HP5+ rated at EI 200. I have a question out the dilution. In my Paterson tanks, each film needs 300 ml of developer. According to Ilford, one litre of stock Perceptol will develop 5 rolls of film. So in my 5 reel Paterson, I need 1500 ml of developer, or a dilution of 1+0.5. I figured out a time for this of 10.5 minutes @ 20 deg. C. Thornton however is talking about a dilution of 1+2, or 3000 ml, or 600 ml per roll. If I want to go with the 1+2 dilution should I just develope, say one roll with 600 ml of developer, or two with 1200 ml of developer? I know the times are different, but is this the "equivilant" (the benefits of dilution aside) of using 300 ml of 1+0.5? The total amount of chemicals per roll of film is the same in either case. TIA, and hope everyone had a Merry Christmas, John p.s. I'm also getting "Creative Black and White Photography" by Les Mclean. Unfortunately it's on back-order, but they should make a great pair. J.