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Only picked up on this thread recently... hopefully this may give some more insight to the topic.
Amateur AO systems (and they are *adaptive* as they correct the overall wavefront tilt ) are not all equal. They vary in:
1) maximum tilt
2) slew rate
3) optical quality
4) positioning accuracy
5) tracking accuracy
6) jitter (internal noise)
I have used both mirror and refractive based systems, sadly due to calibration difficulties, mirror based systems were discontinued. More the pity as they were *fast* , as with a bright guide star they could easily guide at 30Hz.
The practical limit on AO systems nowdays seems to be about 15Hz
SBIG's implementation is quite strong on points 4 & 5 above as the system is looking at a patch of sky *very* close the what the imaging sensor sees.
Rick, your contradictory FWHM's may not be a problem. Use of AO will often give much taller stellar profiles, albeit with a slightly wider sigma spread at the base.
That said, when the seeing is poor, tip-tilt AO systems don't help much, as wavefront errors easily swamp any positional error. When the seeing is good however, AO can and does bring out very faint stars and structures
that will otherwise get lost in the noise.
Just my 2 cents worth.....
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