I suggest 12 minutes in PMK at 70 degrees, at an EI of 50 to 100. If you want to mix some PMK+ you can get a bit more speed. With a 25 red filter I was shooting at EI 6 and 12--I have to say most of the time the longer exposures gave me better results, but the others were acceptable. I really want to get some 70mm cut down to 120 and try it for some nudes.(posted 8515 days ago)