Re: cold temperature reciprocity

Brian -

I had not heard that TP was on the outs. I guess we can expect that as the years go by.

Cheers -

george

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 --- On Tue 08/17, Brian Reynolds < reynolds@panix.com > wrote:
From: Brian Reynolds [mailto: reynolds@panix.com]
To: pinhole-discussion@spitbite.org
Date: Tue, 17 Aug 2004 12:56:51 -0400
Subject: Re: [pinhole-discussion] cold temperature reciprocity

Pinhole Blender wrote:<br>> > From: "Earl and Patty Johnson" <earlj@comcast.net><br>> > I was showing my pinhole cameras and pictures to a friend<br>> > recently. To my surprise, he is interested in astronomical<br>> > photography. In the course of our discussion, he told me that cold<br>> > temperatures reduce the reciprocity failure effect on photographic<br>> > film. He said that astronomers sometimes freeze their cameras and<br>> > film before an exposure to reduce the exposure time. It is a<br>> > little early to think about pinholing in the snow, but I wonder if<br>> > my friend is correct, and how cold does it have to be to make a<br>> > difference?<br><br>Cold cameras were used in the 1970s. Besides getting the film cold<br>you also needed to get rid of the humidity. Purging the camera with<br>Nitrogen was one way do this. Testing by Michael Covington showed<br>that most people were running their cameras too cold.<br><br>> I don't know about freezing but a friend of mine used to pressure<br>> cook
 his film in a chamber of hydrogen which gave him very extended<br>> ISO for no increase in grain. He had a grant to shoot in Antarctica<br>> during their winters with only star light.<br><br>Gas hypering isn't as popular (or useful) as it used to be. As film<br>technology has changed these tricks have become less and less useful.<br>For example, Kodak's E200 has such a low reciprocity failure that gas<br>hypering it isn't worth the trouble. Tech Pan still benefits from gas<br>hypering, but unfortunately Kodak has announced that Tech Pan is being<br>discontinued.<br><br>-- <br>Brian Reynolds | "But in the new approach, as you know,<br>reynolds_at_panix.com | the important thing is to understand <br>http://www.panix.com/~reynolds/ | what you're doing rather than to get<br>NAR# 54438 | the right answer." -- Tom Lehrer<br>_______________________________________________<br>Post to the list as PLAIN TEXT only - no HTML<br>pinhole-discussion mailing list<br>pinh
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Received on Tue Aug 17 10:32:42 2004