[Peter Ward]

Originally Posted by RickS

Did you see similar results for multiple stars and multiple subs, Peter?

Cheers,
Rick.

Yes

Originally Posted by rogerg

AO is all very well and good if there's a bright guide star, but so often my ST8-XME simply doesn't have a 500ADU+ guide star in the guider chip for anything less than a 15 second exposure. As a result I struggle to see how I'd get value for money out of AO, as much as I'd love to have it

Filter attenuation is indeed a problem with the legacy cameras. That said, I've not found any issues with current systems that place the guide chip ahead of the filters.

Originally Posted by multiweb

Very significant improvement. I wouldn't have thought so. Not by that much anyway.

Well, not whole lot in intensity, but the FWHM reduction makes it worthwhile.

Originally Posted by ZeroID

AO ? Adaptive Optics ?

Yes

Originally Posted by Spookyer

Hi Peter, thanks for the comparison data.

I have never used/owned an AO so if I am understanding this correctly the AO allows you to get tighter stars during each exposure with smaller FWHM readings?

You mentioned you had good seeing what is the expected effect as the quality of the seeing goes down? Would you expect even bigger gains from the AO in comparsion to the same rig without the AO in poor seeing?

I imagine as the focal length of the scope increases the benefits of the AO also increase?

At what focal length scope do you think the benefits of the AO would make it worthwhile having one? I mean at what point would the results be noticeable in a sub image.

Cheers
Brett

To use a marine wave analogy, I find AO works really well when there is a smooth swell, with no chop. i.e stars don't look like fuzz-balls, and indeed results improve with focal length

While I've not seen AO make things better in "fuzz-ball" or seeing, or to put it another way, when the higher frequency atmospheric disturbances dominate the image, I've not seen AO make things worse.

I've not used AO's on focal lengths less that about 1000mm, so can't give you any insight on what the cut-off would be, but I'd wager when your pixel sky coverage approaches 3-4 arc sec per pixel, unless the seeing or guiding errors were absolutely tragic, light will fall on a single pixel anyway, hence no benefits to be had.