Quote:
Originally Posted by Stefan Buda
You have to be very careful with active cooling as you can easily make things worse. In my previous comment I mentioned that even passive cooling with fans can create problems in a large planetary scope.
SCT corrector plates are thin and not much of a problem. Glass is a very good black body radiator (unless aluminized) and a Schmidt plate would quickly cool below ambient if it wasn't for the worm air inside the OTA.
Maksutovs correctors are a different matter. Never go there for planetary.
Fortunately no one is making them large enough to be considered for serious planetary imaging.
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Thanks for that.
There is a TEC Mak Cass 250mm aperture for sale on Astromart. They promote it for planetary. Not sure if its good or not. TEC make great scopes though.
Another TEC scope guy uses a 200ED for planetary and his images are usually pretty nice.
I believe you when you say a 14 inch SCT makes the best.
Greg.