500mm reflex lens for astrophotography?

Started May 24, 2012 | Discussions thread
Pete Berry Veteran Member • Posts: 3,005
Re: 500mm reflex lens for astrophotography?

Rich K wrote:

Thanks to all for the feedback. I got interested when I spotted several of these lenses under $200 (not Olympus, of course). However, I think I'll take a look at a small reflector telescope instead.

A simple reflector telescope will be far more difficult to image through than either a Maksutov Cassegrain or refractor. Mirror and diagonal alignment in a reflector is a tricky process, and the only really sharp region is the center due to coma, without a corrector. M-C scopes under 6" aperture generally don't have user-alignable optics, and generally work at f/10, and have quite flat fields photographically.

Below is a 100% crop of the moon shot with my 480mm/6.0 apochromatic refractor w/ dedicated field-flattener. The moon occupies a bit less than 50% of the full frame height uncropped:


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