Alin, Useful and much appreciated information. Thanks! Pos and neg RMS factors relate to two different scales. The actual conversion factor escapes me at the moment. If I should locate it, I'll put up on list. This isn't to say that the total of all other information you furnished isn't exactly right. Just wanted to make the minor point.
Jack --- Alin Flaider <[EMAIL PROTECTED]> wrote: > > Jack, > > In absolute terms, the negative emulsions have > finer grain than > positive. Indeed, Agfa's best negative, Portrait > 160 with it's > granularity of RMS 3.5 is obviously better than > the RMS 10 of their > best positive - RSX 50. The difference maintains > more or less at all > other manufacturers. > In real world though, the thicker layers of the > positive emulsion > accounts for higher densities that translate to > finer gradations in all > three colour channels. This comes at the expense > of the reduced > exposure range compared to the negative emulsion, > but given a > subject whose exposure range is covered by the > positive emulsion > latitude, the positive delivers a richer image > than the negative and > the continuity of tones hide its higher > granulation giving the > overall better appearance. > In the digital era, this becomes even more obvious > with the post > processing level of the scanned image: the lack of > tones of the > negative emulsion image is immediately apparent as > noise, sometimes > after as little as level adjustment and curve > manipulation to open > the shadows. Despite its smaller grain, the noise > gives the negative > film the contrary appearance. > In my limited experience, the only negative film > that comes close to > various positives (like Provia 100F, CT Precisa > 100, RSX 100, etc.) > in terms of rich image in tones is the Kodak RG50. > Too bad it became > "obsolete". [Flame disclaimer: note that I don't > discuss other > criteria like exposure latitude, colour linearity, > etc.; it's not > the end of the world if I cannot capture all the > subject's details, > to me a good picture should also suggest, not just > depict). > > Servus, Alin > > Jack wrote: > JD> I had a lab owner emphatically contend > that.."positive > JD> film of the same ISO has finer grain than > negative > JD> film". Didn't address b&w. > JD> We happened to be reviewing a b&w print at the > time > JD> and their existed a situation wherein the > subject > JD> couldn't be pursued (customers waiting). > JD> I've since emailed him for a follow-up on his > JD> recommendation that "b&w film be scanned as > positive > JD> film". > JD> If his answer (if received) is at all > decipherable, > JD> I'll forward it. > JD> Does anyone know or suspect what he may be > talking > JD> about? > JD> I've, also, read the RMS charts but, their > results > JD> don't appear to be comparable. > > > > JD> > __________________________________________________ > JD> Do You Yahoo!? > JD> Tired of spam? Yahoo! Mail has the best spam > protection around > JD> http://mail.yahoo.com > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
