Quote:
Originally Posted by AstralTraveller
I have a GSO 10" and it's nice enough. The 10" is basically the same length as the 8" (due to the shorter f-ratio) though fatter but collects >50% more light (the actual ratio is 100:64). It can't beat my 6" refractor on planets or the moon but it eats the refractor on DSOs.
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Hi David,
If your 6" refractor is outdoing you're 10" dob on the moon and planets, I think something isn't quite right with the 10" dob.
I think one of the following issues may be at play:-
1) miscollimation.
2) thermal cooling and stability issues.
3) an astigmatic secondary mirror which can be easily fixed.
4) a dud primary mirror, which isn't so easily fixed.
I have two 10" dobs, one is a 10"/F5 with a very good GSO mirror (the secondary was astigmatic when I got the scope) and the other is a 10"/F5.3 SDM with a Mark Suchting mirror. There isn't a 6" refractor on the planet which will outdoor either telescope as a lunar/planetary instrument.
Cheers,
John B