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Improving Avalon Linear guide settings


Beeko

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Hi All,

Really enjoying using my new Avalon Linear mount. Stars are tight but I'd like to make my guiding graph a little smoother. Can anyone suggest how to tweak the settings on the graph? It was a little windy when I took this screen shot. 

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Hi. Try resist switch for DEC, calibrate near the equator and meridian, drift align, make sure you're east heavy [1] then run the guiding assistant for at least 5 minutes. Take all its suggested values. HTH.

[1]Sorry. It shouldn't be heavy. I stand humbly corrected.

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Thanks for the suggestions but the linear does not need to be East heavy and the guide assistant will likely throw out inaccurate suggestions as this mount is purely driven by belts not gears. Sara, Olly any suggestions?

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You should post the guide log. Screen shots don't give enough information. For instance, you are only showing 200 seconds worth of samples . And the screen shot gives no indication of the size of the corrections as they are auto-scaled and on a different scale to the main graph

That said, its pretty hard to say how you could improve much on what you have. If you really want a smoother graph, change the x-axis scale to 50 and the y-axis scale to 16" or even 16px Then it will look almost flat :icon_biggrin:

 

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Will try to see if I've saved the logs. The guiding for the night was pretty much all like this but I've seen graphs with this mount that are almost flat! Just wondering how people do it and if it'll improve performance. 

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Firstly, you don't run east or west heavy with the Avalon, it's a belted mount and so needs balance. I n longer have the Avalon, so can't offer any real time help, but on my website here I have the settings in PHD that I used to use :) 

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Certainly don't run out of balance but you know that.

The Avalon is at its weakest in wind. From the sample you show here I would suspect that the spikes are wind gusts and that with those out of the way the RMS would be significantly better.

I use 1 second subs, as you do, and I give the guide assisstant a good few minutes then apply it. I calibrate in the same part of the sky as I'm imging. Mine is the EQ6-electronics version and I have it set to 0.5x sidereal, not the lowest value as recommended by Avalon. I don't know how the guide rate is specified in the Stargo or whether it can be changed.

I always feel that the real guiding is, with the Avalon, rather better than the trace implies. I'm not alone in this view. Remember we don't really know anything about where the scope is pointing. We only know where the guide star was on the chip at the time of correction. The seeing affects the apparent position of the guide star anyway, and what happens between guide corrections? We don't know! Because of its 'fast reverse' the Avalon may well be put back on target faster than a normal mount and so spend longer in the right place between corrections. This would explain my strong impression that a given guide trace gives a better result on the Avalon than would be the case with a worm and wheel mount like our EM200 or EQ6.

Polemasters. Hmmmm.... my personal jury is still out. A guest gave me a run of subs from his Polemaster aligned Avalon, saying he was confident the PA was good. When we aligned the first and last sub on the stars using 'translation and rotation' there was considerable rotation on the image frames. When we aligned on the stars using 'x-y only' the frames aligned but the corner stars were in entirely different places. PA wasn't that good after all. You could try this test on yur own run of subs.

Olly

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50 minutes ago, ollypenrice said:

Polemasters. Hmmmm.... my personal jury is still out. A guest gave me a run of subs from his Polemaster aligned Avalon, saying he was confident the PA was good. When we aligned the first and last sub on the stars using 'translation and rotation' there was considerable rotation on the image frames. When we aligned on the stars using 'x-y only' the frames aligned but the corner stars were in entirely different places. PA wasn't that good after all. You could try this test on yur own run of subs.

Olly

I have a Polesmaster and have used it a few times - Last time out I checked the PA after using it and it was poor..... I got it much closer with PemPro software. So in my experience, Polemaster certainly doesn't work for me.

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1 hour ago, swag72 said:

I have a Polesmaster and have used it a few times - Last time out I checked the PA after using it and it was poor..... I got it much closer with PemPro software. So in my experience, Polemaster certainly doesn't work for me.

Interesting. Not just me, then.

I always drift align but that's fine in a permanant setup. The great mystery is why others don't use the Tak polarscope system which is fast, easy and good enough for almost all imaging needs. 

Olly

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5 hours ago, Beeko said:

Will try to see if I've saved the logs. The guiding for the night was pretty much all like this but I've seen graphs with this mount that are almost flat! Just wondering how people do it and if it'll improve performance. 

PHD2 saves the logs automatically in Documents\PHD2. What I was alluding to, tongue in cheek, is that the appearance of the graph is highly dependent on the graph settings. So don't go by the appearance of PHD2 graphs.

Tweaking the guiding settings is unlikely to give much improvement over what the guiding assistant recommends.

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