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
You are right, John. I should have not said contrast mask when I
meant the orange mask. The point was that I have difficulty even
identifying the subject matter of a color negative much less how
perfectly exposed it is.
--
Winsor Crosby
Long Beach, California
?
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|