From: Greg Schmitz (gws1@columbia.edu)
Date: 09/12/03-04:09:10 AM Z
Sorry, but I can't keep my fingers off the keys. There is no
difference between "density" and opacity. Go back and have a look at
your textbooks. I think somebody already pointed out the relationship
of opacity to density. Varying degrees of "opacity" are equivalent to
varying degrees of density they are just expressed (mathematically) in
a different fashion, but only if you're dealing with densitometry. Do
you really thing about "density" when you photograph a tree?
I think the confusion may stem from confusing methods used to read
reflected density (reflected light actually) and transmitted density?
It is possible that no light is making its' way to the paper, but
rather that light which strikes the pigment is being reflected back
from the pigment (hint - stop thinking in terms of gelatin/silver
processes). Correct me if I'm wrong, but I think what Katherine means
when she uses the term opaque is that no light is being reflected from
the paper base, but rather the light is being reflected back from the
surface of the pigment. A warning to those folks versed in
Sensitometry - color densitometry is much different than B&W and
colorimetry even mores so (IMHO :*).
-greg schmitz <gws1@columbia.edu>
==================
All of our current environmental problems are unanticipated harmful
consequences of our existing technology. There is no basis for
believing that technology will miraculously stop causing new and
unanticipated problems while it is solving the problems that it
previously produced.
Prof. Jared Diamond, UCLA
Harper's Magazine, 2003 June
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