This is an out-of-focus star shot. (Capella, in Auriga.)
Ideally, I should have this more centered in the viewfinder. Anyway, what you look for is perfect symmetry. This is pretty close. I'm going to tweak it a bit when I get some special hardware from Bob's Knobs. They're knurled-knob screws to replace the ones in the secondary mirror of my Celestron 11" CST. Bob's Knobs make it easier to adjust--no screwdriver needed.
Posted by Dave