From: Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Date: 10/31/01-05:46:19 AM Z
Judy Seigel wrote:
> ... -- I think it was Carl Weese said the idea is to get the
> tone a bit up off the toe by making it 90% black. ...
But without being slave to some 90% number. It is very important that
the photographer select their own black, that is the 100% black that
they will accept as the maximum possible black from their negative. Not
a 90% black.
A toe or straight line portion of the film can be selected to somewhat
control the amount of separation in the blacks. But the boundary on the
tonal values of that end is the maximum black, and this is the value
that should be set. If the film characteristics are not able to provide
the desired separation (local contrast), other contrast control
techniques are available to be used.
A problem with selecting only the 90% black (or some other less than
100% black) is that there is no assurance that the negative will be
capable of producing a 100% black. For example: if the 90% black is not
in the proper location on the D-logE curve (such as the horizontal
portion of the toe), a 100% black may not be achievable without
darkening the entire print or increasing the contrast. It should be no
surprise that the most difficult prints are those of long dynamic range,
low contrast, and full tonal range (like those printed well with the
Pt/Pd process). This requires careful control of both film and print.
Again, this 100% black is what I have called the maximum black, not the
maximum density or D-max. Maximum black is selected by the photographer
based on their materials, process, and preferences. It may not always
be a certain percentage of the D-max.
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
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