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Old 10-06-2009, 11:01 AM
skies2clear
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skies2clear is offline
 
Join Date: Oct 2006
Location: Adelaide, South Australia
Posts: 238
Quote:
Originally Posted by ausastronomer View Post
I am just wondering what the mirror quality will be like.

As the mirror gets larger and faster it gets logarithmically more difficult to make and specifically to make well. While a very large number of the GSO and Synta mirrors I have seen have been very good they have been smaller aperture and a good bit slower in F-Ratio. A 20"/F4.3 mirror is starting to push the envelope even for a premium mirror maker. It may still be a ways for the mass produced Asian factories to get right. Buyer beware.

Cheers,
John B
I'd agree with Johns comments here. I wouldn't hold my breath about the quality. At 20", you'd want to be using at least low expansion glass for the mirror substrate.
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