Archived posting to the Leica Users Group, 1997/11/16

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Subject: Re: Many are Cold, Few are Frozen
From: Jim Brick <>
Date: Sun, 16 Nov 1997 12:30:55 -0800

At 10:01 PM 11/15/97 -0800, you wrote:
>> >As far as I'm concerned 3200 even in a freezer and frozen solid will be
>> >affected. Is this technically true? I haven't got a clue. I just know it
>> >can be in the freezer for 6 months and when you go to use it and compare
>> >negs after being in the freezer to negs that were exposed when you first
>> >got the film and there is a distinct overall "fog" look.
>> ANY film will be fogged by cosmic rays over a period of time.  
>In astronomy they sometimes use special cameras in which the emulsion is
>chilled with liquid nitrogen. I was under the impression that film became
>more sensitive (presumably to both visible light and cosmic rays) at very
>low temperatures. Do any of the amateur astronomers on the LUG know
>anything about this? 

Yes. Professional and amateur astro-photographers have been chilling film
for decades. Almost any text, amateur or professional will discuss this.
Over the years, many amateur construction projects have been featured in
the astronomy magazines for building your own film chiller. This is a very
very well known science, and easily do-able by the amateur.