Winsor,
You're close, but not quite. It has an "orange mask" on the film base to
make a fundamental color correction during printing. The CMY dyes in C-41
film are not exactly C, M and Y due to limitations imposed by the silver
and dye coupler chemistries. They are impure. The cyan dye has noticeable
amounts of yellow and magenta, the magenta has a noticeable amount of
yellow, and the yellow layer is the purest.
The solution for this is a masking layer that evens out the extra yellow
and magenta across the entire negative. It develops in such a manner that
the more magenta there is nearby the less yellow develops in the
mask. Similarly if cyan is nearby, less yellow and magenta develop in the
mask layer. This makes the amount of extra yellow and magenta equal across
the entire negative. Yellow plus magenata make orange which is why the
mask looks orange. When making the print with the "orange masked"
negative, it is then possible to compensate everywhere equally for the
additional yellow and magenta.
Thus, it's not for contrast control but to compensate for impure
dyes. OTOH, contrast masking is used some with B/W and with transparency
printing for contrast reduction. As I understand it, the contrast mask is
actually a B/W negative made of the image and registered with it when it's
printed.
Yeah, I know this is yet more techno-babble, but that's why it's there and
how it all works.
-- John
At 19:54 9/8/02, Winsor Crosby wrote:
Doesn't color negative film have a contrast mask layer that makes the kind
of inspection you are talking about difficult? I don't know since I shoot
transparencies. However the few times with color negative materials I
have been unable to tell much of anything from the negative. Not like B&W
at all.
--
Winsor Crosby
Long Beach, California
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