Mike,

Thanks for the correction about mirrors . . . I suppose I was referring to the curvature properties resulting from the employment of Schmidt corrector vs. meniscus.

Thanks also for the clarification on the crescents. So that is what vignetting looks like in a defocused state . . .

Even at best focus, I'm still getting elongation of the stars, so apparently, the Meade R/C is not a good match for my system . . . darn. I guess I'll just have to keep looking. I wish it wasn't such a guessing game, but with a long focuser, filter wheel and uncommon telescope, I guess that's what you have to contend with.

Thanks for your help.