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Interesting thread - thanks Ray. I won't dispute your findings because I've never done any scientific-like testing!! However, I have used an AO-L quite a bit (only at F11.7 on my Tak) and never experienced a degradation unless the AO guide parameters weren't correctly tuned (aggressiveness and, to a lesser extent, slew rate).
I set aggressiveness depending on guide star brightness (guide frequency) and seeing. The higher the guide frequency, the lower the aggressiveness and I moderate this based on seeing. The point being I never try to correct any one guide error with a single correction because that likely means you're chasing seeing (regardless of how good that might be). The objective is to minimize "wander". Wander is a measurement that indicates the amount of position error that has not been corrected (and it can never consistently be zero). Using TheSkyX and an AO-L it's possible to monitor Wander and adjust the AO settings to ensure wander is minimised and also diminished from the values observed without the AO switched on. The intent is to ensure there is at least some benefit to switching the AO on.
Slew rate just limits the maximum correction that the AO is allowed to apply (arcsecs/sec). The maximum correction is the slew rate divided by the guide frequency (Hz). Ie a setting of 10 at 10Hz limits any correction to less than 1 arcsec. This will help avoid over correction when the seeing is bad.
In your case, I'd be interested in seeing your guide error graphs with and without the AO.
Cheers, Marcus
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