Re: [APML] Focusing and temperature change issues during an exposure- advice wanted

[Matt BenDaniel <matt@starmatt.com>]

Use an OTA that does not vary significantly with respect to moderate changes in temperature.

I have a RoboFocus. Most focus mechanisms have some image shift when focus is changed. That might be handled by an OAG, but if you're using a guide scope, it may be best not to have the focus adjust during an exposure.

I anticipate the temperature change and adjust the focus to where I estimate it will be during the middle of the exposure, or at least compensate slightly in that direction. Most scopes get shorter when temperature falls. I adjust the focus just a shade to the outside.

Matt

At 01:44 PM 11/13/2002 -0800, Alan Voetsch wrote:
>...what's the best way to make sure that focus and
>temperature related issues are not screwing up a great shot?

--
Matt BenDaniel
matt@starmatt.com
http://starmatt.com


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