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

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Subject: Re: [Leica] OT was: Low Pressure Sodium
From: Godfrey DiGiorgi <ramarren@bayarea.net>
Date: Sat, 25 Sep 1999 19:14:48 -0700

>If films are not a panchromatic as they are made out to be ...

Few B&W films have an absolutely even spectral sensitivity. Most have 
some dips and bulges in the curve. Similarly, silicon photodiode, CdS and 
Selenium cell meters (built-in and hand-held) have their own dips and 
humps in spectral sensitivity. 

That's one reason why I do a lot of "testing" with films, developers, 
etc. What a meter reads requires interpretation to arrive at proper 
exposure values. 

I once did a portrait series using a very odd light source like the LPS 
lamps. The vertical spikes in the lamp output combined with Technical Pan 
and some weird, home-brew developer that I was playing with (jeez, I've 
even forgotten which home-brew it was now) produced some very interesting 
tonalities with Caucasian skin tones. It was a lot of fun to experiment 
with it and led to a small show which got very nice reviews. 

Godfrey