Archived posting to the Leica Users Group, 1999/09/23

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Subject: Re: [Leica] Re: Low Pressure Sodium
From: Mark Rabiner <mrabiner@concentric.net>
Date: Thu, 23 Sep 1999 20:31:26 -0700

"Michael D. Turner" wrote:
> 
> Anthony Atkielski wrote:
> 
> > From: Mark Rabiner <mrabiner@concentric.net>
><Snip> 
> > > The most efficient form of lighting you can buy!
><Snip>   All you can do is convert to
> > grayscale, or tint the entire photo a different color.  Really ugly if you
> > originally wanted color.
> >
> >   -- Anthony
> 
> Yup. I once visited a semiconductor manufacturing facility which was using some
> equipment I had designed in a cleanroom with sodium illumination. The color-coded
> keys were useless--blue was black, yellow was white, white was white!
> 
> Similar situation with tungsten films shot in high K light or daylight films shot
> in tungsten light sans filtration. You simply cannot correct what is not recorded
> on the film.  Period. And if you scan and try to correct, you just get noise.
> -Mike

The issue in your first paragraph is I think one of discontinuous spectrum.
Scattered Holes where certain colors don't exist at all.
IN your second paragraph it's one of balance. All the colors are there but in
different amounts. Am I right? A warm verses a cold bias.
Mark Rabiner