Quote:
Originally Posted by thegableguy
I see you're a fan of the fast Newts - I expect one of those will be the next OTA purchase.
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It's a matter of economics: Newtonians deliver the most aperture per dollar, and, if you set them up right, perform extremely well. The fact that they're fast is out of necessity: just try imagine mounting and using e.g. a 12" f/8 Newt (which for a 12" Cassegrain would be slow).
If you're going to get a Newt for planetary imaging, you're best off with the slowest mirror you can still manage, and customising the secondary for narrow FOV, minimal obstruction, max contrast. And check out previous posts (going way back) by Bird (Anthony Wesley), IIS's Newtonian planetary imaging guru.