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Hi Matt
I have a CF C9.25 and the main reason I went for it over the Al variant is that for long exposure, auto guided DSO astro-photography, I wanted the minimum dimensional change in OTA with falling temps, so I didn't have to re-focus the 'scope.
The scenario I am describing is say, taking 20 x 3 min Luminance of M83, followed by 10 x 3 mins each RGB, giving an elapsed time of almost 3 hours (including image download times).
I don’t have a temperature compensating focuser nor do I want the additional cost/complexity of getting one, so I figured a CF tube would minimize the need to re-focus over a 3 hour period.
For Lunar & Planetary imaging, I would be prepared to re-check focus more often, especially with large changes in temperature.
Cheers
Dennis
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