Quote:
Originally Posted by bigjoe
ABSOLUTELY TRUE GLEN!
Yet how few take this into consideration when purchasing.
No good getting Lockwood , Zambutto mirrors if your seeing is never better than 2" or so; your average SW mirror's resolution would be better , far better even than required in those conditions
Spending money unnecessarily then , unless its just for" bragging rights"
bigjoe
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I think that this is true for DSO imaging, but for visual use or high speed planetary imaging, even 2" seeing can occasionally stabilise for short bursts to give a diffraction limited clear view and the extra capability of a really good mirror may show through.
having said that, I cannot recall ever reading a negative review of a Skywatcher mirror, including interferometer testing (eg
http://www.cloudynights.com/topic/44...of-my-mirrors/). If there was anything sub-par about them, it should have surfaced by now. There seems to be an understanding that Chinese mirrors are a bit hit or miss, but I suspect that this is one of the many self-perpetuating "truths" that persist on the internet, long after the factual basis for the idea has faded into history..
the other point in favour of the big Skywatchers is the undercut conical mirror structure, which is dead easy to mount and should come to thermal equilibrium relatively quickly - forget about mirror quality if the reflecting surface is warmer than the air or the edge supports are generating astigmatism.