Earlier I wrote:
> > AFAIK, the orange mask on colour negatives is not a uniform density of
> > orange but is developed proportionally to the density of the image.
>
Joseph McAllister responded:
> The base of color negative film is that color. Development of the image
changes
> it ....... not.
>
> On the couple of generations ago minilabs, you had to put a piece of
developed
> and cleared 120 color negative film into the filter drawer to print a B&W
> negative on color paper. Now they do that internally, with a B&W
"setting."
>
The orange mask visible in unexposed, developed colour negative film is the
"background" level of mask that is appropriate to black or no exposure. The
film does not "know" where the frame ends so it extends into the rebate
areas and onto the leader and trailer as well.
What your eyes fail to see is that there is more to the mask than just this
baseline orange, there is additional masking developed into the remainder of
the negative proportional to the brightness and colour of the image that was
exposed.
The general orangeness of the mask helps to keep enlarger filter-packs well
on the positive side of zero in magenta and yellow so that the third filter
colour (cyan) is never or rarely needed.
I acquired this knowledge when I studied photography at Sydney Technical
College in the late '70s - early '80s. I know no reason why our lecturers
should have BSed us.
BTW the colour is in the emulsion, not the base material. Just to be on the
safe side of embarrassment I confirmed this myself a moment ago by
scratching through a colour negative emulsion to the CLEAR base underneath.
Regards,
Anthony Farr
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