Autoguiding choices

[cacophonist]

So what's the difference between a great autoguiding setup and a functional one? If I was going to spend extra money I'd certainly look at kit that is lightweight because I use a SW EQ3-Pro and it won't a load of extra weight.

My initial understanding is that it corrects for movement error in the mount which in my case is not a great deal. Would any guiding make a great difference on my mount?

But assuming I should get at least a basic 50 mm guide scope and a dedicated guide camera what's wrong with the cheapest of the ASI models or is there nothing at all wrong (perhaps at my aperture it's perfectly acceptable to have some error or lack of precision??)

[Stickey]

If you're using a SW EQ/3 Pro then It won't carry the weight of equipment necessary for the sort of Astrophotography that requires "great" guiding.

Having said that, I use a basic 50mm finder/ guider with an ASI120MM as a guide camera but I actually use it with my ASIAir Pro for finding objects and tracking them. It also enables me to use the Polar Alignment feature and if I get it good enough, the mount will track quite well without needing guiding.

If the finder/guider are properly aligned, then the Goto feature will put the target object slap bang in the centre of view in the main telescope. I can spend all night observing to my heart's content, sketch or use a DSLR to image the target. 

So, I'd suggest a finder/guider scope rather than a pure guide scope. 

Good luck in whatever you decide to do. 

Mike

[vlaiv]

33 minutes ago, cacophonist said:

So what's the difference between a great autoguiding setup and a functional one?

Mount

33 minutes ago, cacophonist said:

But assuming I should get at least a basic 50 mm guide scope and a dedicated guide camera what's wrong with the cheapest of the ASI models or is there nothing at all wrong (perhaps at my aperture it's perfectly acceptable to have some error or lack of precision??)

Even modified 30mm or 50mm finder scope and web camera will get you 90% there. It is fully functional system on any cheap mount.

Your problem won't be guide system - your problem will be mount.

[cacophonist]

Thank you both, that's really helpful!

I'll of course upgrade the mount in time but at least for now I won't spend more than a few hundred on guiding when I have such a basic mount.

[Budgie1]

1 hour ago, cacophonist said:

My initial understanding is that it corrects for movement error in the mount which in my case is not a great deal. Would any guiding make a great difference on my mount?

What you have to ask yourself is; Am I happy with my exposure times without guiding? If you're currently getting good results with 30 second exposures and no start trails then maybe that's all you need. If you want to try longer exposures, anything up to 5 minutes, then guiding allow you to keep the target in view and the stars round during longer exposures.

You may be able to just use a 30mm guide scope & a ZWO ASI120MM Mini camera, linked into an ASIAir or a laptop running PHD2 software. This would fit onto the finder scope mount and shouldn't add that much weight to your rig.

[Xilman]

1 hour ago, cacophonist said:

Thank you both, that's really helpful!

I'll of course upgrade the mount in time but at least for now I won't spend more than a few hundred on guiding when I have such a basic mount.

You may wish to consider a software solution before, or as well as, spending money. It will not be anywhere near as good as a decent mount or a decent autoguiding system but it may well help.

Essentially, find out the difference between a true point object and what it looks like after it has been through your system and onto the camera. That is the point spread function (PSF) and is the combination of seeing, diffraction effects, optical misalignment, poor guiding and more besides.

Once you have your PSF you can then feed it into deconvolution software. As I said, it will not solve all your problems but could well improve your image quality. From my experience it can improve resolution by a factor of somewhere between 1.1 and 2.0 and I have a good mount and optics. What I rarely have is superb seeing.

Do not expect miracles. Do not use it if you wish to perform precision photometry or it will destroy your measurements --- that is why I rarely use this technique.

 

One further thing: it is likely that a half-way decent autoguider will improve the results even after getting a better mount, so your investment is unlikely to be wasted. At the very worst, it won't harm anything.

Edited December 9, 2023 by Xilman
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