Archived posting to the Leica Users Group, 2000/07/25
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]on 25/7/00 5:53 pm, Tim Spragens at t.spragens@cityweb.de wrote: >> From: Peterson Arthur G NSSC <PetersonAG@NAVSEA.NAVY.MIL> >> >> I had long understood that underexposing and overdeveloping increases >> contrast. And somewhere, somehow (I can't recall and can't explain >> it), I had gotten the impression that, conversely, overexposing and >> underdeveloping rather decreases contrast. > > This was the lesson drilled into my by my instructors, and seemed > to be proved true in the lab. Long time since I've read the standard > texts, but someone would have to blast the memory from my brain > with solid reasoning and examples. As I recall, overdeveloping will > also increase grain size. Overdeveloping increases highlight density, while areas of low exposure develop to completion. Thus overall tonal scale is expanded. Underdeveloping means highlights do not develop to their full density, while areas of low exposure still develop to completion (or nearly). Thus overall tonal scale is contracted. There's your contrast control right there. Exposure is just a question of which tones you are parking in the middle of the curve (and whether you get blocked up highlights or no shadows). It doesn't affect contrast, unless you are massively under or over exposing. I know in reality it's more complicated than that but as a first approximation it's about right, I think. - -- Johnny Deadman http://www.pinkheadedbug.com