Tuesday, February 05, 2002, 11:03:11 PM, Shel wrote: SB> This "silver rich" business has me puzzled. What do people mean by SB> this? What do you mean by it? Recently there was a comment on this SB> subject on the Pure Silver list, and the commentator - someone held in SB> high esteem for his knowledge and experience - said that the "silver SB> rich" theory is so much nonsense, and that the newer films have a good SB> deal of silver in them, it's just that their grain structure is SB> different.
SB> I believe that there may be "more" silver in older emulsions, but I SB> don't really know. Maybe older emulsions need more silver because the SB> grains of silver are more random in size and shape than T-grain or SB> Delta-style films. Hi Shel, I am no expert :( but this is what I think about it. Of course, there is much hype (not hypo <g>) and legends in photography, so it indeed might be all hypo :) New emulsions use monosized crystals. These would have no tonality at all though, so they have to combine at least two (D3200 has 4 or 5 IIRC) layers to get nice tonality. Why? Remember, sensitivity of silver grain is proportional to its size (or more precisely, area exposed to light). Silver grain doesn't register tones, it just is "on" or "off". Monosized grain layer has same sensitivity all over, so ideally, would register only black or white, and produce a half-tone screen (is evenly spaced, it would be very similar to halftone screens used in printing biz). Actually, the screen is more stochastic. Tones in B&W are mostly from different sensitivities of grains, that's different sizes of grains. In monosized modern emulsions, they combine several layers of different sensitivity to achieve better tonality. In "older" emulsion, there are many different sizes of grains mixed together, thus many grains of different sensitivities mixed together. Some people say that the old type films are better for many subjects like portraiture because they can distinguish more shades of gray in small exposure differences than modern films. Whether this is true or not I do not know, there are so many variables and personal views in B&W that I just try something and if it works well I like it. But I have indeed seen some classical film prints which had great tonality, comparing favorably to tonality of contact printing LF. What makes it even more difficult is that apparently, HP5+, FP4+, TX, PX and similar are all thin-emulsion "wonderfilms" introduced in their modern form in 70-80, having much thinner emulsion thus being quite sharper than the older thick emulsion films. Some people say because of this thinner emulsion, there is less mixed grainsizes, so tonality suffers in the thin-emulsion films. This might all be bullshit for all I know of the technical side of things, but I have seen 35mm prints from classical type film developed with good old Rodinal, which indeed had exquisite tonality. All this makes sense to me, but like in everything scientific, making sense and being true can be different things (or not). Good light, Frantisek Vlcek - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
