Re: pinhole Eclipse fun

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From: Paul Doherty (pauld@exploratorium.edu)
Date: Tue Jun 11 2002 - 08:52:48 PDT 

Message-Id: <l03110713b92bcca59a0d@[192.174.3.125]>
Date: Tue, 11 Jun 2002 08:52:48 -0700
From: Paul Doherty <pauld@exploratorium.edu>
Subject: Re: pinhole Eclipse fun

Hi Ben

Welders glasses shade 14 or higher are safe for solar viewing 24 hours in a
row.

They block out UV, IR and visible.

Black and White negatives totally exposed are NOT safe any more.

The old silver emulsiion films were fine since they blocked UV and IR but
the new dye based negatives are dangerous. Unless you know what you are
doing avoid photographic film.

I believe your tree leaf question deserves some experiments.

Paul D

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