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Old 13-11-2013, 05:48 PM
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Bassnut (Fred)
Narrowfield rules!

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Join Date: Nov 2006
Location: Sydney
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Quote:
Originally Posted by alpal View Post
We can only compare the results that manufacturers claim.

Still - I wonder if RC designs have been superseded?

No matter what system you buy it always needs a corrector
which is just extra glass that will introduce it's own aberrations -
especially halos on bright stars.
I sort of agree RC designs have been "superseded" in that similar performance can be obtained on "corrected" designs for way less money eg CDK.

But "No matter what system you buy it always needs a corrector" is not quite correct really. My RC set up has no glass at all, mirrors only. A flattener (glass) is recommended for larger sensors on my RC, but I get away without one. Assuming your correct that glass introduces aberrations, then thats one problem I dont have, so that must be an advantage on an RC not available on other designs I guess.

I dont know if not having glass makes any other difference. I focus every 2 weeks or so, does glass itself cause focus change with temperature?.
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