Quote:
Originally Posted by clive milne
At typical focal ratios, the focal plane is sufficiently under sampled by any ccd that you are likely to encounter that there is no noticeable improvement to be gained by a mirror more accurate than 1/3 wave.
GSO mirrors are typically much better than that so are as good as you need. The issues surrounding cheap tube assemblies are related to deficiencies in the mechanical design (not the optics)
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You know, thats a well put understated definitive conclusion thats should solve all endless arguments about optics. Ive compared subs Ive taken with my Meade 12" LX200R and an RCOS 10" in urban skies. With the LX200R in perfect focus and colomation and perhaps a bit of decon with decent data, I cant tell the difference between them apart from the extra depth from the 12".
The huge difference is in the tube mechanical stability, I focus the RCOS every 2 weeks or so and the secondary focuser/thermal management (fan/heater control) is insanely accurate and reliable. I havent colomated the RCOS in years.
If your willing to put the effort (im not) into countering these mechanical deficiencies, then you can save a lot of money for the same result. The old rule applies, less money, more effort for the same result, its doable.