To gauge if your 7" and larger Mak or SCT is up to scratch, here's a few target objects that you can try. Best thing about these items is they are either planetary or lunar as it is all about extended object resolution which is much finer than the Dawe's Limit (
see this link for more info on the actual resolution of telescopes and associated thread).
Also, perfect seeing conditions is not mandatory for these. On the contrary, some thermal distortion is GREAT as it will really test the optical quality of the scope and an indicator that some tweaking of the retaining ring may be an easy fix, or even collimation. You will be maxing out the scope's magnification with these too.
Planetary
* Encke Division in Saturn's rings.
* Fine festoons and smaller cyclonic swirls on Jupiter. Colour contrast an additional trick.
Lunar
* Craters Armstrong, Aldrin and Collins - if you cannot see all three, especially Collins the smallest at 2.5km diameter, you have a very sick scope! You should be able to resolve knife-edge details as thin as 150m, and finer with scopes 10" and larger.
* The thin rille that cuts down the middle inside Vallis Alpes (Alpine Valley)
* Fine rille inside crater Campanus
Struggle to see any of the above, even with seeing conditions say at 7/10, then the opitcs need some attention, including collimation.
And of course the above test targets also apply to all 7" and larger instruments, not just SCT's and Maks.
Alex.