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Posted by Richard Crowley on 07/03/06 12:05
"Bill Farnsworth" wrote ...
> Get yourself a rosco cinegel color correction sample
> set. (1 1/4" x > 3")
> Then you can experiment with white balance through
> different correction filters.
Great idea. I knew all those gel sample packs would
come in handy some day! :-)
Alas no amount of white-balance or painting the R/G/B
gains/pedestals will produce a "color" picture under a
source as monochromatic as sodium vapor. Not with
electronic video, nor with chemical film.
We have a similar situation in the cleanroom fabs where
we manufacture microprocessor wafers (perhaps the one
in the computer you are reading this on!) . Part of the fab
is illuminated with orange light that looks for all the world
like those "bug lights" people use for porch lights to
avoid attracting insects. The photo-sensitive "resist"
that we use to expose the patterns on the wafers is not
sensitive to this partiuclar wavelength, so it is very much
like a photography darkroom "safelight".
But the light is so unbalanced that it is nearly imposible
to properly white-balance under. One of our cameras
will almost do it, but we discovered that people who
are looking at the video become disoriented when they
see the "litho area" looking as if it were illuminated in
white light. So our SOP is to white-balance in the white
illiminated area, and then to just shoot in the yellow
litho areas as-is and let the video go yellow.
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