"?what was wrong with the mirror locks?"
Hi Dave
Imo, nothing.?The mirror locks work very well holding and maintaining?the mirror "flat" relative the rest of the optical components,?even?though?the mirror?shifts sideways. When I stopped the mirror shifting laterally, the star trail?problems stopped too.
Fwiw, and imo related, The doughnut hole of?a defocussed star, when looking at a star at the zenith vrs near the horizon, shifts a little, but not a much. However?a?dust particle, (becoming nicely visible?in the defocused state)??shifts A LOT, In fact about as much as a star would trail over that same amount of OTA?movement.
As for differential flexure of?the many of the components,... with an?identical setup put?on either?the?C11 or Meade 10" OTA, swapping only the OTA,?the problem would?come or?go, respectively, to the same amount, every time.
I did?wonder if the C11 OTA was flexing?so much?as to be?part, or all,?of the problem.?The Meade castings (classic, circa 1997)?are heavier, and?the connecting tube is both?glued and bolted to both?the front and rear castings. The C11 castings are lighter, and?are?bolted only. But once I?prevented the mirror from shifting? relative to the rear casting, that?pretty much solved the problem, so?I'd have to say flexure of the OT?is not much of a problem. I'd bet the built in mounting rail is?a necessary part of the?structural rigidity. I have one on top too, which probably helps too.
I don't mind going to OAG. It's just that I was forced to well?before I was ready to.?Along with the C11 Edge, I bought a cooled CCD camera to replace my DSLR. That meant I would be able to?go beyond the?10-15min?subs I was accustomed to getting.?Given the info Celestron provides about the Edge, I think it was?reasonable to?expect I'd be able play with my new camera and scope for a year or so, using a guide scope,?within the 10, maybe even 15min?limits,?before spending the $?for OAG, to go further.
