FotoDave@aol.com
Wed, 13 Jan 1999 03:51:56 -0500 (EST)
I have defined a few terms, so I will use them in the discussion below. The
definitions are not strict or 100% accurate technically, but they are mainly
for communication.
Most alt. processes work in a continuous-tone rather than binary manner. If
you take a piece of carbon tissue and expose it without any negative for 0.5,
1, 2, 4 mins.... you get different tones. The tones are based on exposure
which causes different *thickness* of hardened gelatine. This is more apparent
if one uses thick gelatine but weak pigment concentration.
Therefore if one uses a "true continous-tone" negative, the final print will
have a 3-dimensional effect. The darker area is thicker than the lighter area.
Of course, whether this effect is considered beautiful or ugly is a personal
preference, but it is a distinctive effect nevertheless.
If one uses a "true binary" negative, the final print will also have some
thickness, but each dot will have the same thickness. The difference in tones
is not caused by different thickness but by different distribution of black
dots.
Sil has pointed out that there is no pure, true, theoretical contone negative,
and Wayde has explained that there is no pure, true, theoretical binary
negative. But my question (and interest) is which negative is closer to which?
I am not just trying to argue for contone vs. binary. I have a real interest
in this because I like the thickness effect! (Even gum has this thickness
effect although it is only apparent when it is wet. Once it is dried, the gum
arabic dries to a relatively thin layer so one can't really tell if the dark
area is really thicker than the thin area).
And here is why I often say that camera negatives are closer to true contone
negative because although the silver particles are opaque, they are suspended
in gelatine layer, so when light passes through them, they were partially
absorb (see Stroebel's Photographic Materials and Processes). I think this is
espeically true if one uses large format negatives and make contact prints
because there is no enlargement. In this case, the darker area will indeed
give thicker layer.
I haven't seen many carbon prints (to be honest, just less than 5), but since
this relief effect is described in a few books, I assume this is true. That
means a continous-tone negative can indeed be close to what I called the
"true" contone negative.
Now about the digital (dotted negative). I had no question that that it would
give continous-tone appearance when the resolution were high. The shadow
casting, blurring due to diffused light, difraction, etc. described by Wayde
are all true (assuming your emulsion can print continous tone, of course). I
have seen the effect under a loupe. I just never thought or read about the
explaination as he excellently detailed. In fact, the dots look like softened
grains, so in that sense it appears to be like a print made by ordinary
negative.
But my question (not my assumption or theory, just question) is, doesn't this
continous-tone effect happen *around* each dot? Each dot will have a darkest
area and gradually soften to clear area (or not so clear sometimes). But since
the effect is *around* each dot, the whole print would have the appearance of
the same thickness. Well, each dot will have a relief, but since it is so
small it's probably not perceivable. (in fact, wasn't the lack of relief one
of the complains that people had with Evercolor pigment print?)
My rough guess is, if I make print with a 35mm enlarged to 11x14 (so that
grains are visible), then the effect might be compatible with a digital
negative, but if I use a large format and make contact print, then my print
would probably look different from the one make from digital negative. Here I
am not talking about image manipulation by computer or if you blur the grain
and use unsharp mask to sharpen the image in Photoshop. I am talking about the
feel and the physical relief characteristic of the print.
So many as we all start to use digital negatives, the difference might not be
continous-tone versus digital, but large format vs. small format? Oh my, there
is no new thing under the sun.
What do you think? Any idea, comment, technical discussion? If this doesn't
belong to the list or if it doesn't interest you, I apologize. For those
interested, maybe we can discuss it off list?
Thanks for listening!
Dave
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