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I read both sides of this argument here and elsewhere and I don't get it. Logically what Ray is saying has to make sense; seeing will be different in different parts of the FOV. If the AO makes a correction based on seeing only around the guide star - and - seeing is different (or moving in the opposite direction elsewhere in the FOV) then part of the image should improve at the expense of areas in the remainder of the FOV.
However, if the mount is tracking improperly, then what the AO sees around the guide star applies to the rest of the FOV providing that seeing is reasonably good.
So, if I've got that right, I don't understand why many are seeing improvements with high end mounts (like ME, MEII, APs etc) where protrack and great polar alignment can provide terrific 10 min unguided round stars.
The only explanation that comes to mind is that perhaps seeing really doesn't always vary so much over the FOV on average. Certainly I can see the benefit to using AO on lesser mounts. I just don't understand from any theory why a really high end mount properly set up should see such improvement. I'm not doubting anyone's statements to the contrary. I just want an explanation.
Peter
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