Quote Originally Posted by albada View Post
Delta 100 was interesting because, unlike all other developers I've tested, Ilford evidently did not use the ISO method of determining speed. If they had, the speed would be at least 200 and the darker shadows would be nearly black and indistinct. That's because this film has a long toe, and at the ISO speed point of 0.1 above B+F, the slope of the density-curve is still too low. I've been measuring contrasts using ISO speed points, and got odd results with Delta 100 until I figured out what was going on.

Mark Overton
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I am not a chemist or chemical engineer, I grope my way by trial and error without the aid of sophisticated analysis machines. I have found Delta 100 to perform to my liking by rating it at 125 - 150. Using Kodak produced Xtol my development times are less than 8:00 with Jobo rolling development. I do not pre rinse. I like your findings and hope you will detail the formula's for the Concentrate and D316 in layman's form.