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Not really sure Greg,
Its not really my area of expertise
It depends a lot on what you are trying to achieve and what camera you prefer to image with.
The AOL and AOX both operate slower than the AO7
I think the AO8 was in between
The AO7 used a tilt/tip mirror and thats why the camera sits perpendicular to the optical path, whereas the later AOs used a prismatic tilt/tip arrangement - its just flat parallel glass - so its a straight through light path.
As the design changed from mirror to prism and the size of the glass has progressively increased to cater for bigger CCDs, the increased mass has meant that the energy to tilt/tip has also increased - somewhere along the line the constraints of effective operation has meant that the maximum correction frequency has gone down.
So the AO7 can correct at higher frequencies than the others - but obviously only with a smaller aperture - aka smaller CCD chip
Is this good or bad ? - I'll leave that to others to argue about !
Some will say its a big disadvantage as you cannot correct for higher frequency wavefront aberrations, some will say it doesnt matter as this type of adaptive optics is so limited by its low overall frequency that any gain is better than nothing, and that the best we can hope to correct is only the slow stuff anyway !
Truth is all of these AOs are barely able to correct 50% of the movement
The Pros would like to be able to correct at high speeds up to 1000Hz which is difficult for mortals, but I think typical speeds are maybe 100Hz
But they are also trying to truly use adaptive optics for correction for the shape of the wavefront aberration which is much different to a simple tip/tilt correction.
The AO7 could go to about 20+Hz I think - the internal guide camera is only doing at most about 40 frames per sec anyway and it took about 10ms for the mirror to fully react to any move
The later AO models were much slower - 10Hz or less - I think they took about 50ms to react to a full move
So this makes them very good for high speed guiding correction which is useful - but really for true AO I think they are quite limited
In answer to your specific question If the 16803 is your chip of choice being a square STL11000 then that is really the constraint.
The underlying software will be the same, the speed of the AOX and AOL is probably about the same - I havent checked and havent owned an AOX so Im not sure about it - havent even read a spec sheet !
But you would still only be able to use an AOL (or AOX) with the STL11000m - the AO7 and AO8 are too small to cover the chip and the AO7 has some rotational effects occurring that would make things even worse on a big chip.
I think you need to assume that what you are going to get is much better guiding, so it keeps your stars centred without bloating due to continual wobbling between guide intervals - any magic for true adaptive optic correction isnt likely.
This is only relevant for longer focal lengths, atmospheric effects will mean that what is happening on one corner of your CCD is not necessarily the same as what is happening on the other ! - ie there is enough physical distance in the lower/middle atmosphere between these stars across say an angular patch of sky across 30-60 arc secs.
So the gains may or may not be there across the complete image, but your guiding will be better !! and that will improve your FWHM - better stellar profiles.
You can use a ST7 for AO control by using a Remote Guide Head - so the camera can be positioned on top of the OTA rings for arguements sake and just plug the RGH into the MOAG - makes life easier if you have the spare $500+ worth of RGH laying around.
The other thing is that the latest SBIG cameras and AOs mean that the guide camera is in front of the filters not behind with the main chip on the ST, STL series. This makes guiding especially high speed better - especially if you are using NarrowBand, but if you are using an RGH and ST7 then that has already been achieved anyway. So that makes good sense as a cheaper option too.
Bit of a ramble - hope it helps
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