Re: [APML] Self hypering camera from Taurus-tech?

["westergren" <westergren@netzero.net>]

Bert and all,

The testing Wallis and Provin did was a long time ago, with mostly B&W
films.  The color negative films then weren't anything like today's film.

I have done two film tests that I haven't reported on before.  I tested the
New RG200 with 12 hours vacuum at 50°C (same as hypering temp & time).  One
film was at hand pump vacuum, about 27.5 in Hg.  The other was a hard vacuum
at about 100 torr.  Neither one shows any benefit from the treatment
compared to untreated, unhypered film.  I chose the RG200 to test this way
because it absolutely needs hypering to work for us.

I haven't tested any B&W films, so I don't know if they would respond to
vacuum or drying or whatever.

Keeping the film dry in the camera is very important to keeping the film
from expanding and buckling and losing focus.  I believe, but haven't tested
whether humidity cancels the true hypering while overnight in the camera.  I
keep my film dry all the time.  In fact I use the whole southern CA desert
to keep my film dry.

Don

From: "Bert Katzung" <katzung1@attbi.com>


> According to Wallis & Provin in A Manual of Advanced Celestial
Photography,
> straight dessication and nitrogen soaking does have a definite effect in
> improving film sensitivity/reducing reciprocity failure. The magnitude of
> effect in their Table 10.2 is only graded into slight, effect(ive), and
very
> effective, plus avoid, but  they rate nitrogen soak or bake as Effective;
> forming gas soak or bake is Very effective.
>
> In another place they say that dessication and oxygen removal are
essential
> in the hydrogen-sensitizing process and imply that this holds for any type
> of sensitization.




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