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Old 30-11-2019, 10:36 AM
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Paul Haese
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Join Date: Jan 2009
Location: Adelaide
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Quote:
Originally Posted by billdan View Post
Wow that's a big secondary (102mm), my 14in f4.65 Skywatcher only has an 80mm secondary in it.
I guess shorter focal lengths need larger secondaries.



Bill, viewing Newtonians don't need as large a secondary for that reason. Astrographs require a larger secondary for imaging. The secondaries on my AG12's are 110mm and but have focal lengths around 1180mm.
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