First light for my 8" Dob. It came with 25mm (48x) and 10mm
(120x)Plossls. Deep space was very nice, but I don't think I'm getting
the sharpness I should be getting:

-in focus, with either eyepiece, stars don't show any diffraction
pattern or rings...only a disk which is slightly grainy/sparkly on the
bright stars at 120x (my cheapo 60mm Jason refractor shows textbook
diffraction patterns/rings). Look at the left star pattern in the
following link...this is what bright stars look like:

http://www.geocities.com/beerauth/dobstars.2jpg.jpg

-moving very slightly out of focus on either side of focus, I start to
get a hint of rings forming, but they're faint, indistinct, and broken

-moving more out of focus on either side, I get a nice round doughnut
(but no rings)

-Castor could split at 120x, though barely, and somewhat grainy (look
at the right star pattern in the link above)

-on Saturn, I had a very very difficult time seeing the Cassini
division

-slight blue and orange fringing on planets (maybe it's the
eyepieces?)

-in M42, the Trapezium resolved to 4 stars at 120x (don't know how
many an 8" should show)

Is something wrong, or is this about right for an 8" f/6 Dob? Skies
were very clear (I could see M37, M36, and M38 naked eye with averted
vision when Auriga was near zenith), though it was windy. I got the
same results using it slightly out of collimation as it came, and
again after collimating it almost perfectly.
I'm thinking it could be: the main mirror, the presumably cheap
Chinese-made eyepieces, or seeing conditions.