Archived posting to the Leica Users Group, 2002/02/17
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]It's been a few years since I did black and white, but when I discovered XP, followed by XP2, I stopped using any other B&W film. What I did learn about it was to rate it at ISO 200 if I wanted the best results, and I found those results to be superb. On the other hand, at ISO 400, the results were so-so, and at ISO 800 completely unacceptable. Here is the explanation the I have read and concurred with. In the thin places on the negative, the dye clumps do not overlap, giving the appearance of grain. With sufficient exposure, those thin spots will correspond to the darkest shadow areas, i.e., black on the print, where the "grain" will not be visible. With general underexposure, the lighter (on the print) areas will suffer from this phenomenon. Question: Why have I not noticed this effect with color negatives? Perhaps it is because the lack of overlap is hidden since there are three emulsion layers--a gap in one layer could be hidden by the existence of dye in one or more of the other layers. Herb - -- Herbert Kanner kanner@acm.org 650-326-8204 Do not meddle in the affairs of cats, for they are subtle and will pee on your computer! - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html