----- Original Message ----- From: Subject: Exposure: was New digital cameras
> > On B&W or color negative film you really > > only need to be within a couple > > of stops. Most pros are probably at least that good from constant > > practice. > > > This is one of the most absurd statements i have ever heard, > especially comining from someone who purports to be a photographer. > > Try a little test: shoot a scene two stops under, and with 1/3 or 1/2 > stop increments to two stops over. Look at the negs. Have quality > prints made. You'll see that even 1/2 stop away from "ideal" exposure > will result compromised results. There are many factors at play here. The exposure range of the scene may be very long, but still within range of the film, and a small exposure variance will push the scene outside the exposure range of the film. Or, the scene may fall well within the range of the film, by several stops, in which case an exposure variance of a stop or less may cause negligible quality loss. Also, the direction of exposure error matters. With negative film, under exposure will show up very quickly, whereas moderate over exposure may improve things, may in fact be your "ideal" exposure. The type of negative film makes a difference. If the curve is long and straight, with a short toe (T-Max 100), as long as the exposure range of the scene fits fully into the range of the film, the resulting exposure can be considered correct, and may result in an allowable exposure variance of a couple of stops. Even the amateur grade negative films have exposure ranges now of eight or so stops. Most scenes in nature are less than six, and in the studio, may be as little as three. OTOH, one can use the slope of the film to one's advantage. Tri-X in HC110 B has so much toe that it is possible to separate out the most amazing amounts of shadow detail by merely expanding development a stop or so. Of course, this will blow out highlights, so it is best to be prudent about the range of the scene, or perhaps deliberately underexposing somewhat. For your little test, I could set up a two stop scene, and have an exposure variance of several stops with little to tell between them on the print. Or I could set up a very long range scene and have no ideal exposure. I am sure there are many pros out there who couldn't guess an exposure to save their life, they have always used automated cameras on automatic, haven't had to learn that part of the craft, and haven't ever had a problem. William Robb
