Posts Made By: Ron Sowers

Do you mean using an equitorial mount for tracking instead of the alt-az mount?
It would be easier to track with, but an EQ mount that would handle an 8 inch dob definately would be less portable than the dob's original mount. Tripods, with the head and counter weights are more difficult to transport.
I have a 6 inch newt on a EQ mount, and a 10 inch dob, and I can actually get the 10 inch dob out in the back yard faster and easier than I can the 6 inch.

Hope that helps!
Ron

OH man!!!!!!!!!!!!! $%%$##$#$

I hope not too!!!!

Ron

I think it's an adjustable popcycle stick ;-)

Ron

Mirrors only have the tolerance in the center since they have a central obstruction, the center of the mirror is blocked so an error that is the size or smaller of the obstruction wouldn't affect optical quality.

I remember seeing that image that you describe in Suiter's book, I don't have it handy right now, maybe someone else does? It seems to me it was an indication of a turned edge, but that's for a newt, I'm not sure what the equivalent abberation would be on a refractor, anyone correct me if they know :-)

I just ran the abberator program and set it for zero central obstruction (refractor) I can get close to an intra/extra focal image where there is a black dot in the center by adding some spherical abberation and adjustion the focus waves. How did the rings look between the two sides? Were they fuzzy and mushy on one side and sharp on the other?

Ron

Can you some how use a mask, either make a central obstruction OR mask off the outer to just leave the center and get a better analysis that way? If the center is indeed bad, then by masking out most of the outer "good" area, you should see the star test show more of the real abberation the center is displaying.