Archived posting to the Leica Users Group, 1999/09/25

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Subject: Re: [Leica] OT was: Low Pressure Sodium
From: Mark Rabiner <mrabiner@concentric.net>
Date: Sat, 25 Sep 1999 12:31:59 -0700

><Snip> 
> But no detail at all is rare.  Low-pressure sodium is one of the few situations
> in which there is no detail at all.  Actually, it's no so much that there is no
> detail, as that the detail in all three channels is proportionately the same, so
> there are no differences that can be exploited to recover actual color.  Not
> surprising given that the LPS spectrum is bright-line and monochrome.  I hate
> LPS lamps.  I guess they'd be okay for black and white, though.
> 
>   -- Anthony

As you had said a few days back it is virtually monochomatic. And that specific
slice of the spectrum is what your paper doesn't see I guess as it is the
safelight of choice. If films are not a panchromatic as they are made out to be
and if you meter is more responsive to its wavelength than you film is you would
be underexposing your shots a tad. Very dark shadows go clear. I'm thinking
black and white all of a sudden here.
Mark Rabiner