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GEM45 auto guiding with Asiair


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Morning All

Im pulling my hair out (what’s left of it) with auto guiding an Ioptron GEM45 with ASIAIR Pro.

when I leave the very limited settings available as std on the AAP guiding,

0.5x guide rate, 2000ms, AGGR RA 70%, AGGR DEC 100%

performance is shocking !!! BIG sharp spikes above and below the 0 line for both axis. Anyone else had this issue and overcome ?

The only way I could get reasonable guiding was to back the aggr WAY off in both axis !! This seems at odds with my other mount I was using that was a tuned eqm-35 pro that was impeccable on the std settings at around 0.5arcs RMS.

Suggestions pleeeaase…

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21 minutes ago, newbie alert said:

How well are you balanced?

Did you run the guide assistant and apply the settings?

Your RA and DEC should go either side of the trend line otherwise it's showing your PA is out 

Very well balanced, Ioptron doesn’t have any friction at all when axis are unlocked so balancing is not guess work, there is no guide assistant in aap guiding.

PA was within 1min, not the best but not bad.

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8 minutes ago, Newforestgimp said:

Very well balanced, Ioptron doesn’t have any friction at all when axis are unlocked so balancing is not guess work, there is no guide assistant in aap guiding.

PA was within 1min, not the best but not bad.

The axis on the ioptron are very fluid, I have a cgem 60 myself.. but also they highlight the 3rd axis that also needs to be balanced

I don't rate the air, never had one but the figures never translate to what phd is saying in its native state.. but usually in a obscenely low rms figures, that don't translate to what the graph tells you peak to peak

Can't you run phd as a standalone software? Seems pointless not to have all of its  functions 

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6 minutes ago, newbie alert said:

I don't rate the air, never had one but the figures never translate to what phd is saying in its native state.. but usually in a obscenely low rms figures, that don't translate to what the graph tells you peak to peak.

That is quite a significant statement.  What evidence leads you to that conclusion? 

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I appreciate I could use Phd2 from the laptop and I may well return to that method and the suggestions the guide assistant would provide aren’t present in AAP, but the AAP works so well for everything else I don’t want to give up on it, and would rather persevere with it.

As I say if I back the AGGR way off the graph looks much more reasonable but I’m not experienced enough to manually diagnose autoguiding to know if this is the right thing to do or if I should be looking at the guide rate, exp time or some other setting in AAP guiding.

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14 minutes ago, Newforestgimp said:

I appreciate I could use Phd2 from the laptop and I may well return to that method and the suggestions the guide assistant would provide aren’t present in AAP, but the AAP works so well for everything else I don’t want to give up on it, and would rather persevere with it.

As I say if I back the AGGR way off the graph looks much more reasonable but I’m not experienced enough to manually diagnose autoguiding to know if this is the right thing to do or if I should be looking at the guide rate, exp time or some other setting in AAP guiding.

It’s the right thing to do if you get round stars. Proof of the pudding and all that. :) 

Forgive a silly question, but have you checked you input the correct guide scope focal length and guide camera pixel size?  The wrong values could display the wrong guiding error. 

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1 hour ago, GoldTop57 said:

Might be worth reducing reducing the guide rate. Also what settings do you have for Max DEC and RA duration? I found this article useful when I was setting up my mount:

https://eastwindastro.blogspot.com/2021/02/how-to-adjust-asiair-guide-aggression.html?m=0

Funnily enough I just found that article and it seems I was inadvertently doing what the article suggests, so I will make a more conscious approach next session with this article as a guide.

currently at the standard 0.5x and 2000ms max 

I’m beginning to think that the mount is actually working VERY well with limited guide corrections required whereas at the beginning I thought the mount was a dud !!

Edited by Newforestgimp
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1 hour ago, Ouroboros said:

It’s the right thing to do if you get round stars. Proof of the pudding and all that. :) 

Forgive a silly question, but have you checked you input the correct guide scope focal length and guide camera pixel size?  The wrong values could display the wrong guiding error. 

Tbh I can’t remember entering a pixel size, I selected my guide camera ASI120MM and the f/l as 200mm as taken from the William optics site for the WO 50mm uniguide slide base.

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1 hour ago, Newforestgimp said:

Tbh I can’t remember entering a pixel size, I selected my guide camera ASI120MM and the f/l as 200mm as taken from the William optics site for the WO 50mm uniguide slide base.

OK. Well, it was worth asking. I have noticed that my ASIair sometimes forgets some or all of the settings between sessions. (I don’t know why. You’d have thought it would either always remember or always forget wouldn’t you?) And I think you’re right. It already knows the pixel size from the camera model. 

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5 hours ago, Ouroboros said:

That is quite a significant statement.  What evidence leads you to that conclusion? 

Several reasons why.. 

Because people think they're guiding at the figures that the air is telling them .. even thou they're using a Chinese mount but getting figures that a mesu would be happy with.. 

You can't have a graph that's reading over 2 secs peak to peak with RMS in the .3 range

Some have compared the air with phd2 standalone and if drastically differs 

So with that plus the connection issues, it's ability to forget what equipment it's being used with ,i stand back and not race to the shops to buy one..

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As I understand it the ASI Air Pro is using a cut down version of PHD2, so I would be surprised if there is a difference between the figures reported by the app and the figures reported by PHD2 in standalone mode on a PC - where are the reports that there is a significant difference? (the numbers I have been getting on my Losmandy on the ASI Air Pro look comparable to what I was getting when I ran PHD2 on a laptop before I got the ASI Air Pro)

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I have a StellarMate setup with A Frac and an ASIAIR setup with a Samyang 135 and used both on my trusty old NEQ6. Both showed between 0.6 and 1 RMS all night so my experience leads me to trust the Air figures. I now use the Air setup on my new Gem45 and it’s between .45 and .65 all night. Next time I set up I will jot down my settings   I admit that neither setup weighs more than 5kg so not really pushing either mount. 

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On 30/09/2021 at 08:24, Newforestgimp said:

Ioptron doesn’t have any friction at all when axis are unlocked

I think that this statement is significant. The mount is considerably different from your previous SW mount and probably runs a lot smoother. It would therefore need less aggression in the guiding pulses. And your description of large + and - deviations sugessts the same.

What I would do is to hook up the mount to PHD on a laptop, create a new profile, and run the guiding assistant. Then use its recommended values as a baseline for AAP guiding.

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37 minutes ago, wimvb said:

I think that this statement is significant. The mount is considerably different from your previous SW mount and probably runs a lot smoother. It would therefore need less aggression in the guiding pulses. And your description of large + and - deviations sugessts the same.

What I would do is to hook up the mount to PHD on a laptop, create a new profile, and run the guiding assistant. Then use its recommended values as a baseline for AAP guiding.

Thinking the same, I was getting fantastic guiding from the SW EQM-35 and expected better out of the box from the GEM45, with the responses here and further research it’s almost behaving as if the mount needs minimal corrections. It just seemed alien to drop the AGGR values down below 50%

now I understand the logic a bit more I will start with very minimum values and build up rather than starting with standard and everything bouncing around.

my hesitancy in using the guide assistant is it will no doubt suggest making changes to settings that aren’t available on the AAP version of phd.

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1 hour ago, Richie092 said:

I have a StellarMate setup with A Frac and an ASIAIR setup with a Samyang 135 and used both on my trusty old NEQ6. Both showed between 0.6 and 1 RMS all night so my experience leads me to trust the Air figures. I now use the Air setup on my new Gem45 and it’s between .45 and .65 all night. Next time I set up I will jot down my settings   I admit that neither setup weighs more than 5kg so not really pushing either mount. 

That would be magic !!

much the same here I have a very light set up currently which could also contribute to the minimal guide nudges required.

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I am having a similar problem with a GEM28EC using PHD2.  I have the exact same result using Linux/INDI or Windows/ASCOM.  Per manufacturer recommendations, my drivers turn off the PEC chip.

The result is marginally acceptable guiding with occasional spikes and non-specific intervals.  Best guiding is TOTAL RMS error of 1.29" with typical "stable" guiding of 1.5" over long periods separated by random spikes up to 6.0"  The spikes occur 1-3 in a batch after which the mount settles down again.  All the testing has been done in areas where a meridian flip wasn't going to happen any time soon.  Polar alignment was spot on with iPolar (although PHD2 Guiding Assistant reports it as very slightly off).

Reducing the AGR and MinMov helps most.  I'm currently using 75 RA/50 DEC and about half what Guiding Assistant recommended for MinMov.  Guiding Assistant isn't much real help in this instance.  I sent PHD2 logs to iOptron at their request, but haven't heard back yet.

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On 30/09/2021 at 07:44, Newforestgimp said:

Suggestions pleeeaase

Hi

-  Look at the numbers if and only if the images from your main camera are not to your satisfaction.

- Adjust polar alignment to around 5' error.

Cheers

Edited by alacant
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1 hour ago, JonCarleton said:

I am having a similar problem with a GEM28EC using PHD2.  I have the exact same result using Linux/INDI or Windows/ASCOM.  Per manufacturer recommendations, my drivers turn off the PEC chip.

The result is marginally acceptable guiding with occasional spikes and non-specific intervals.  Best guiding is TOTAL RMS error of 1.29" with typical "stable" guiding of 1.5" over long periods separated by random spikes up to 6.0"  The spikes occur 1-3 in a batch after which the mount settles down again.  All the testing has been done in areas where a meridian flip wasn't going to happen any time soon.  Polar alignment was spot on with iPolar (although PHD2 Guiding Assistant reports it as very slightly off).

Reducing the AGR and MinMov helps most.  I'm currently using 75 RA/50 DEC and about half what Guiding Assistant recommended for MinMov.  Guiding Assistant isn't much real help in this instance.  I sent PHD2 logs to iOptron at their request, but haven't heard back yet.

That’s really interesting, I too am getting the high PEC around 6” and when that passes it settles to around 0.8 RMS before again hitting what i assume is the PE.

experimenting last night I was running on

Guide rate 0.25x

AGGR RA 20%
AGGR DEC 20%

(I have no option for min move on the AAP version of phd, only AGGR and guide rate.)

Certainly not the usual advice of “just use the std settings”.

this seemed to give a nice neat graph hunting the 0 line all bar the assumed PE peaks and dithers.

Would be interested to hear what iOptron have to say.

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1 hour ago, alacant said:

Hi

-  Look at the numbers if and only if the images from your main camera are not to your satisfaction.

- Adjust polar alignment to around 5' error.

Cheers

Hi,

Regarding your suggestion for PA accuracy, you've said 5minutes was this intentional or did you mean 5 seconds ?

 

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2 hours ago, Newforestgimp said:

Good, 5’ I can do, 5” would take all night !

The mechanical construction of altitude and azimuth adjustments on most mounts don't allow for better than a few arc minutes in polar misalignment. Whenever I try to really zero in on PA, I notice that I adjust it to different positions without really improving. Two bolts pushing against a metal block are just not that accurate.

In my experience (with a sw AZ-EQ6 mount), belt tension and backlash adjustments are more important for smooth guiding than accurate polar alignment.

Btw, those low numbers for guide rate and aggression make sense for a smooth running mount. A "rougher" mount needs more force to get it moving. And a smooth mount will keep on moving (overshoots) if it gets too much force.

Edited by wimvb
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