Scope temperature: Newtonian vs SCT?

[Solanum]

Previously I have used a 10" dob and leaving it outside to cool for an hour made a big difference to the view, with air visibly moving if I didn't. Now I have an SCT, but my reason for changing was to have something I could take out and use for relatively short sessions away from home (ie I can't take it out and elave it).

So my question: is getting the scope down to air temp as important for an SCT? Obviously, it still has air in it which can be influenced by the mirror/tube/etc., but as the tube isn't open maybe that isn't as big a deal?

[raymo]

SCTs suffer just as badly as Newts, and take longer to cool to ambient,
because obviously, the tube is closed, and also the glass corrector plate at the front absorbs quite a lot of heat, as does the solid mirror/ end
plate assembly. If the scope is significantly warmer than the outside air,
a cool down time of 45-60 mins is indicated for imaging work.
raymo

[Visionary (David)]

I only have the courage to ask this question as we are in the Newbie precinct. What if you placed cold packs onto your scope? Or is the problem one of achieving an ambient-consistent temperature drop across the whole instrument?

[acropolite (Phil)]

http://www.lymax.com/sct/. wouldn't be hard to make one, a simple fan, filter and some PVC pipe and fittings.

[ralph1]

Originally Posted by Visionary

What if you placed cold packs onto your scope?

When I used a hot pack to remove dew while observing, I found that the change in temperature was uneven across the mirror and it became impossible to focus for ten minutes after. I would suggest that a cold pack could have the same effect.
Ralph