ATM Star Testing Results

[Brad Davy <bdavy@bigdog.fred.net>]

I finally got the collimation on my 8" f8 right, and had a good night of
seeing.  Turns out that with sky glow, my limiting magnitude is around 6-7
(based on observation of M4).  Star testing on Polaris reveals circular
images both inside and outside of focus, with the diagonal shadow perfectly
(to my eye) centered, and no obvious coma.  Now for the bad part.  I can't
make out any diffraction rings.  The out of focus images are pretty
uniformly lit, with a very bright ring at the outer edge.  Mars is a bright
disk, but no features (polar caps) are evident.  Could this be an edge
effect?   My choices for improving the view are mask off the outer 1/8-1/4"
of the primary or install baffles (yes I know, do both).  But I'm
interested in comparing the effects of each.  Any suggestions as to which I
should do first?

FWIW, my wife and kids got their first look at the moon last night through
the scope.  After griping about the time I spent in the basement perfecting
this, my wifes first words were "Oh my God!!"  

Thanks.
Brad
bdavy@fred.net               http://www.fred.net/bdavy/home.html
bdavy@nox.cs.du.edu