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A couple of points relating to previous posts:
1) In practise ,its a complete myth that a larger scope is somehow going to show less than a smaller one in inclement seeing. A smaller scope will show superficially sharper images , but will never show more than a bigger telescope, and the larger scope will always generally show more even poor seeing.
A classic memory I have of this - an APO showing a crisp small dim image of Jupiter with some festoons at the `just visible' level. At the same time a mediochre Coulter 17.5" showed a large bright softer looking image with breathtaking level of detail in the belts due to colour perception and image scale - numerous features of all different colours because there was enough light to activate the cone cells which were completely invisible in the 7" APO and the 17.5" was operating no where near its resolution limit.
2) Central obstruction issue is way overrated. Any larger telescope with a visual optimised secondary below 20% suffers negligible effect on the Contrast Transfer Function according to Dick Suiter . Similarly spider vanes although creating a visible spike do not significantly effect planetary contrast unless exceeding 1/128 the aperture in thickness according to Suiters Star testing book. Another red herring !
My 14" Newt with 20% obstruction and standard 3 vane spider , has shown salt and pepper granulation inside certain markings at Mars opposition which I have been able to correlate with photos from the HST....
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