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 ) 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
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