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Re: Moisture Inside a SCT....????UPDATE..

Started by Eblanken, 12/29/2003 02:44AM
Posted 12/29/2003 02:44AM Opening Post
Steve,

Here's a couple of thoughts:
(1) be careful to get the corrector oriented back in the
same radial relation to your scope's main mirror,
(2) There are sometimes small shims that are used to
get the spacing right on the corrector, so I hope you
noticed if these were used and got them back too,
(3) the dessicant approach or the forced air (CAT Cooler,
etc.) might be a lot more effective and less of a hassle
than removing the corrector each time this happens,
(4) if you can lower the Relative Humidity at normal room
temperature (68 to 75 degrees F or 20 to 25 degrees C)
then you will have more sucess. A "rule of thumb" that
I've used is that the % RH will double for every ten
degrees C (or 18 degrees F) that you lower the temperature.

For example if you have 50 % RH at 25 degrees C, you will
have 100% RH below about 15 degrees C (thus your scope will "fog
inside"), so if you can "trap" drier air (like:the relative
humidity down to below 20 % RH at 25 degrees C) then you
can take the scope down to 5 degrees C and still have
about 80% RH inside your scope (no fogging since % RH is
still below 100% inside).
I hope that helps,

Ed

P.S. Does anyone use "dry nitrogen" to purge scope
interiors of excess moisture ???