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Posted by David McCall on 07/03/06 14:41
"Richard Crowley" <rcrowley@xpr7t.net> wrote in message
news:12ai1vr8c61quf4@corp.supernews.com...
>
> 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.
>
Good points. I once tried to get an HL-79 to balance under
raw sodium lights and it really looked awful. There just isn't
anything for the camera to work with. The spikes are in the
middle between Red and Green, with no Blue at all.
What you said. If there is any part of the scene (or scenes
adjacent to this scene) in which the Orange lighting is visible)
that has full lighting, then white balance to that. Otherwise
just use your tungsten preset (3200) and let it be orange.
You can tweak it a bit in post, but it will never look close.
There just isn't anything but orange. You can reduce the
saturation and shift the hue a little. But that is about it.
I think Paul's video looked real good. We are used to that look,
so it really doesn't look out of place.
David
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