equipment Avalon X-Guider - Need Advice

[DeepSkyMan]

Ok, so this is a follow up to my earlier post, I’ve almost convinced myself to pull the trigger on The Avalon X-Guider,

http://www.avalon-instruments.com/products/x-guider-telescope-guide

but I’m hoping for some feedback from SGL members before I make the final commit.  Looking at the animation on the Avalon website the operation looks pretty slick however there is one area that concerns me and that is initial alignment of the device with the optical axis of the main OTA.  It appears that this is wholly dependent on the mechanical attachment to the OTA, in my case this will be the X-Guider Vixen clamp to Vixen (CGE) dovetail bar.  Is there an ability to fine tune this attachment with the X-Guider in addition to the normal Alt-Az adjustment.  Is this even an issue to concern myself with?  Also what is the build quality and function actually like in the flesh, it’s too easy these days to be fooled by glossy web-site advertising?

Would also appreciate additional feedback from anyone who uses the X-Guider.  I will be going for the clamp top and bottom variation as this seems the cleanest solution for attachment to my existing setup.  In addition to the X-Guider I will need to purchase a dovetail bar for attachment of my finder rings to the X-Guider, some recommendations in this area would also be welcome, although I think the 140mm Primaluce Labs bar looks ideal for this purpose (being of similar livery).

Kind Regards

Paul.

[ollypenrice]

You need have no fear concerning the engineering quality of Avalon products. It is absolutely excellent.

However, this attractive bit of kit is a solution to a problem which doesn't exist. Why would you be so determined to align your guide scope to your imaging scope? Historically imagers used to use adjustable guide rings, not to align the guidescope with the main scope but to do precisely the opposite, which is to say move the orientation of the guide scope in search of a bright enough guide star. In the bad old days of guiding by eye, and the slightly less old or bad days of guiding with the low sensitivity ST4 autoguider, it was necessary to move the guide scope in search of a guidable star. Now it never is. (Well, in the last ten years of running commercial imaging setups for guests I have never, ever, failed to find a guide star and my guide scopes are bolted down hard but with no attempt made to align them with the imaging scopes and no facility for changing their orientation.) In recent years the myth has arisen that guidescope and imaging scope need to be aligned. They simply don't. If you are polar-misaligned then your images will rotate around the guide star so, sure, ideally this would be in the middle of the image. But in reality the likely misalignment between guidescope and imaging scope using non-adjustable clamps will be insignificant and the solution, in any case, is to refine your PA.

So I've no idea why anyone would buy this device! There is, however, a need for alignment devices aimed at those using dual or multiple imaging rigs but that's another story.

Olly

[gorann]

15 minutes ago, ollypenrice said:

You need have no fear concerning the engineering quality of Avalon products. It is absolutely excellent.

However, this attractive bit of kit is a solution to a problem which doesn't exist. Why would you be so determined to align your guide scope to your imaging scope? Historically imagers used to use adjustable guide rings, not to align the guidescope with the main scope but to do precisely the opposite, which is to say move the orientation of the guide scope in search of a bright enough guide star. In the bad old days of guiding by eye, and the slightly less old or bad days of guiding with the low sensitivity ST4 autoguider, it was necessary to move the guide scope in search of a guidable star. Now it never is. (Well, in the last ten years of running commercial imaging setups for guests I have never, ever, failed to find a guide star and my guide scopes are bolted down hard but with no attempt made to align them with the imaging scopes and no facility for changing their orientation.) In recent years the myth has arisen that guidescope and imaging scope need to be aligned. They simply don't. If you are polar-misaligned then your images will rotate around the guide star so, sure, ideally this would be in the middle of the image. But in reality the likely misalignment between guidescope and imaging scope using non-adjustable clamps will be insignificant and the solution, in any case, is to refine your PA.

So I've no idea why anyone would buy this device! There is, however, a need for alignment devices aimed at those using dual or multiple imaging rigs but that's another story.

Olly

Yes, Olly is of course right - no reason to align a guide scope if you have a reasonably sensitive camera (almost any of the low end ASI or QHY would be fine). However, the device looks ideal for a piggy back camera with a telephoto lens on top of your scope since it would allow you to frame the wide field telephoto image quite precisely. They should sell them with that in mind instead. It is a pity it is so expensive since I would like one.

Cheers

[swag72]

I agree with Olly..... unless you are looking at using your guider also as a finder scope (as I did for some time before the days of plate solving) then I see no reason at all to have the guider aligned precisely with the the imaging scope. Just bolt the guide scope down facing in the same direction as well as you can by eye and that will be sufficient for guiding purposes for sure.

If you are determined that you want to use this, then it will be a good product I am sure. I used the cheaper Skywatcher guide scope alignment saddle for a while.... my guiding was no better with the guider being perfectly aligned by the way  

[DeepSkyMan]

4 minutes ago, ollypenrice said:

You need have no fear concerning the engineering quality of Avalon products. It is absolutely excellent.

However, this attractive bit of kit is a solution to a problem which doesn't exist. Why would you be so determined to align your guide scope to your imaging scope? Historically imagers used to use adjustable guide rings, not to align the guidescope with the main scope but to do precisely the opposite, which is to say move the orientation of the guide scope in search of a bright enough guide star. In the bad old days of guiding by eye, and the slightly less old or bad days of guiding with the low sensitivity ST4 autoguider, it was necessary to move the guide scope in search of a guidable star. Now it never is. (Well, in the last ten years of running commercial imaging setups for guests I have never, ever, failed to find a guide star and my guide scopes are bolted down hard but with no attempt made to align them with the imaging scopes and no facility for changing their orientation.) In recent years the myth has arisen that guidescope and imaging scope need to be aligned. They simply don't. If you are polar-misaligned then your images will rotate around the guide star so, sure, ideally this would be in the middle of the image. But in reality the likely misalignment between guidescope and imaging scope using non-adjustable clamps will be insignificant and the solution, in any case, is to refine your PA.

So I've no idea why anyone would buy this device! There is, however, a need for alignment devices aimed at those using dual or multiple imaging rigs but that's another story.

Olly

Olly, thanks for your as usual educated feedback.  In my particular case however, at least initially, I will not be using the X-Guider for guiding, but instead as a base for a conventional finderscope, (see my earlier post).  I find that one of the major issues, bearing mind that I need to setup everything from scratch for each observing session, is getting accurate alignment of my 80mm finderscope with my Edge OTA. The thumbscrews just don’t cut it for me.  The idea with the X-Guider is to cut down on setup time with having an initial baseline that is at least close to required alignment, then use the alt-az adjustment on the X-Guider for final accurate alignment.  Additionally my hope is to venture into EAA/ AP at some point in the future and it struck me that I might as well invest in quality accessories for when I make this step.

Paul.

[ollypenrice]

1 minute ago, DeepSkyMan said:

Olly, thanks for your as usual educated feedback.  In my particular case however, at least initially, I will not be using the X-Guider for guiding, but instead as a base for a conventional finderscope, (see my earlier post).  I find that one of the major issues, bearing mind that I need to setup everything from scratch for each observing session, is getting accurate alignment of my 80mm finderscope with my Edge OTA. The thumbscrews just don’t cut it for me.  The idea with the X-Guider is to cut down on setup time with having an initial baseline that is at least close to required alignment, then use the alt-az adjustment on the X-Guider for final accurate alignment.  Additionally my hope is to venture into EAA/ AP at some point in the future and it struck me that I might as well invest in quality accessories for when I make this step.

Paul.

Well I'd expect this to make a very nice finderscope aligner! Not cheap but it ought to do it sweetly. However, when it comes to guiding an SCT I really think you should use an Off Axis Guider. As a way of aligning your finder, Rolls Royce!

Olly

[gorann]

Yes, for just aligning your finder you may go for the cheaper Sky Watcher option that Sara once used. Looks OK. I never had a problem with the normal finder scope holders - they can be adjusted. This one is for heavier things, Mercedes style (or Rolls Royce as @ollypenrice puts it, which are nowadays also German cars)

[DeepSkyMan]

17 minutes ago, gorann said:

Yes, for just aligning your finder you may go for the cheaper Sky Watcher option that Sara once used. Looks OK. I never had a problem with the normal finder scope holders - they can be adjusted. This one is for heavier things, Mercedes style (or Rolls Royce as @ollypenrice puts it, which are nowadays also German cars)

Goran, I’m looking at the X-Guider because of the lower weight, 440g v 1038g.  My mount is a Sphinx SXW, so I’m always conscious of the mount capacity 500 odd grams is a significant weight saving.  I also bought a second hand Skywatcher Guidescope mount last year, which turned out to be the one and only time that UK ABS has let me down (the azimuth adjustment was broken).  The damaged azimuth axis aside, I was rather underwhelmed by the overall build quality :-)

Paul.

[gorann]

46 minutes ago, DeepSkyMan said:

Goran, I’m looking at the X-Guider because of the lower weight, 440g v 1038g.  My mount is a Sphinx SXW, so I’m always conscious of the mount capacity 500 odd grams is a significant weight saving.  I also bought a second hand Skywatcher Guidescope mount last year, which turned out to be the one and only time that UK ABS has let me down (the azimuth adjustment was broken).  The damaged azimuth axis aside, I was rather underwhelmed by the overall build quality :-)

Paul.

Good to know!

Cheers

[DeepSkyMan]

Thanks guys for your feedback, I’ve now placed an order with The Widescreen Centre for the X-Guider, seems like they are now the only official outlet for Avalon kit in the UK.

[AngryDonkey]

It's a nice piece of kit and really light which for me was also the main reason for choosing it (and paying the rather hefty price). It certainly manages to deliver what it promises - I use it for a WO71 plus Moravian 8300 and it manages to hold it rigidly in place without any problems. The only small downside I found is that you can't lock the azimuth adjustment in place. The screw and spring will hold it just fine but on more than one occasion I have turned the azimuth adjuster knob by mistake and buggered up the alignment. I've since stuck a small cube of foam on it to stop me from being stupid