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Old 20-09-2013, 08:22 PM
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Shiraz (Ray)
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Join Date: Apr 2010
Location: ardrossan south australia
Posts: 4,918
Newtonian systems produce off axis coma. The standard parabolic mirrors require relatively expensive 3 or 4 element coma correctors to get rid of it without introducing a degree of spherical aberration. Hyperbolic mirrors can be pretty well corrected with 2 element coma correctors, but the main mirrors seem to be more expensive to make.
The results are basically the same for both and the extra glass of a properly made corrector should be no concern.

Explained in http://www.telescope-optics.net/sub_..._corrector.htm

agree with Wavytone that the Maksutov corrected spherical Newtonian systems are a good choice.
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