[Shiraz (Ray)]

There is no simple answer Aidan - depends on too many interacting variables. However, although the SBIG marketing guys are gung-ho on AO, their tech guys are more realistic. "Based on our experience and knowledge, AO-L and AO-7 rates help only slightly with reducing ground layer atmospheric turbulence, but are quite effective in reducing guide errors and wind buffeting"

As I see it, the big problem with AO is that the major amateur implementation is being marketed as though it offers some of the ability of the professional systems to cut through seeing - when in fact it simply cannot do so when used as recommended. It helps correct some mount errors and is likely to be effective in good seeing and with mounts that are normally used with slow guiding updates (or that have inherently lower quality). In average to poor seeing it can certainly have a detrimental input to the guiding, but whether that will over-ride the advantages from improved mount correction will depend on other factors in the guide system.

It would be interesting to see what difference AO makes in a comparison where the mount+AO is compared to mount-AO at the same update rate. There is an assumption that mounts cannot correct at high rates, but I cannot find any data that shows if that is a reasonable assumption.