AO guiding

[Peter Ward]

In case you missed it, SBIG, aka Diffraction Ltd, have just announced their new StarChaser guiders....that finally deliver for non-SBIG users, AO supported guiding.

Admittedly, if you are using a 3rd party camera, it will not be a simple bolt-on (read you'll be spending some money at Precise Parts), and the guider plus AO will probably cost more than a low end Chinese camera...but...first order AO is now available for those that want it.

Interesting times!

[Atmos]

I wonder how these will compare to the SX AO versions as a way of doing AO with 3rd parties.

[codemonkey]

I wonder how much backfocus it'll take up. Lots of correctors have stringent ~55mm spacing requirements... that's a problem with the SX unit, otherwise I might have looked into getting one in the past.

[Peter Ward]

With an AOX around 52mm.... and enough aperture to allow 16803 sized sensors.

[Slawomir]

Thank you Peter for the heads up.



Can an Active Optics unit be placed in front of a corrector? Star shapes for the guide camera would be yuk, but perhaps the system would work well anyway?

I also thought about such unit in the past, but I’m concerned that it adds complexity and not sure how long the motors that constantly move the prism back and forth last.

[Peter Ward]

Yes, you could place the AO higher up the imaging train. But I'm not sure whether you'd see any distortion as a result.

My AOX is about 5 years old...still works flawlessly. The SBIG version does not use motors. Electromagnetic coils are use to modulate a "floating" refractive element's position.

[Slawomir]

Good to know - thank you Peter.

As for star shapes in front of the corrector - I believe that uncorrected field curvature in front of a flattener and far away from the optical axis will most certainly result in highly elongated star shapes in a guide camera. Whether that would impact guiding - I don’t know.

[gregbradley]

I think that would only be for short focal length fast scopes.
Longer focal length scopes or perhaps slower scopes do not seem to do that.

I see different star shapes with different scopes using a MMOAG to guide.

It doesn't seem to make any difference to the guiding anyway as the software calculates the centroid.

Greg.

[gregbradley]

Peter,

Diffraction Ltd website only mentions SBIG cameras as being supported by these Star Chaser guiders.

So to be clear, these guiders can run an AO using a FLI camera and filter wheel?

Greg.

[Peter Ward]

I'd obviously check with DL before I took anyone's money (Australian consumer law and that "fit for purpose" clause) , but yes, the Starchaser hardware will drive the AO, independently of the camera.

That said, I don't know whether MaxIm has a "lock-out" AO clause with non SBIG cameras....and will get a definitive answer soon.

[gregbradley]

Yeah that would be good as I have wanted an AO solution for some time.

Greg.

[Slawomir]

Me too! I just wasn’t sure about reliability and longevity of the existing SX AO, otherwise I would have tried it a while ago. Electromagnetic means of moving the prism has rekindled my interest in trying an AO.

[Peter Ward]

The definitive answer is, yes, the Starchaser 2/3 will guide plus drive the AO and AOX systems without needing a SBIG camera back end.

The rub however is.....you will need to get the appropriate adapters custom made to ensure a mechanical AND optical match to get focus with the guider and camera. SBIG will not support such efforts, so if you stuff up the back focus calculation for your particular camera...not their problem.

Of course, you could always buy the new 4k by 4k SBIG sCMOS camera announced at the 2019 AIC...:)

[codemonkey]

Ouch... counts me out!

[Peter Ward]

What..spacing or the price tag? :)

SX also offer a solution I was unaware of until recently....requiring around 20mm more back focus. No matter, if it won't fit, it won't fit.

[codemonkey]

haha both at the moment, but I was referring to the backfocus requirement. I guess I could do it if I moved to OSC... other than that it'll have to wait until I've paid off the mortgage and buy a CDK or similar and thus have a lot more backfocus.

[Paul Haese]

I would like something like this for my Newtonians, but back focus is an issue with short back focus on coma correctors. Great idea though.

[Peter Ward]

DL have been beavering away in the background for a while now
one of these (http://www.atscope.com.au/sbig/AlumaAC4040.html) would be nice too...but likely to run $A25k....less than FLI's Kepler...but not chump-change either.

One can always pray for a $A rally... :lol: