Trying to diagnose Asiair Pro guiding issues, can someone take a look at the detailed log I have?

[Jay6879]

Equipment --

 

Star Adventurer Pro 2i

Canon t3i Ha modified

Zenithstar 61ii

Asi 120mm mini

Asi 30F4 guide scope 

 

 

 

Ok so for the first month or so that I had the Asiair Pro it worked phenomenally. I could set everything up and go to sleep, let it run the whole night no issues. I do that at least seven or eight times. There have been multiple updates to the AAP since then and I can't figure out if this is a software issue I'm having or it's hardware?

 

There have been numerous threads and numerous people who have mentioned issues with guiding, especially since the multi star update but it's hard to say for certain if the issue was update related since there are so many hardware combinations out there.

 

So the other night I was out for around three hours and tried all sorts of different settings and combinations to remedy the issue and I'm hoping I managed to get enough data to be useful. I'm still quite new to all this so I don't fully understand the nuances of what's contained in the guide log so any help is appreciated. 

 

Here is the issue, I will set up calibration (single star or multi star, it doesn't seem to matter) and everything will go fine. I am easily getting 2 minute subs with round stars and could go longer. Unguided it appeared 60 seconds was max with the Zenthstar 61ii before stars went oblong so it is obvious the guiding works. I will get six to seven subs in and the RA guiding goes wild. I've seen it shoot up 50"! The star is completely lost.

 

Here is a screenshot of my polar alignment...

 

Throughout the night when checked through plate solving my DEC moved less than 2', I slightly adjusted it once if I remember correctly. Everytime the guiding went wild it was only the RA I needed to adjust so my polar alignment is good I believe.

 

As the night went on I tried fiddling with different settings in the app, and it showed some improvement with RA numbers. When it was working it tightened up the RA, at times to sub 1". That's good! Unfortunately, like clockwork, six or seven two minute exposures later and boom it would go wild again.

 

 

I am so close to just being ready to rock here, my setup and takedown routine is *chef kiss*. I can use plate solve to find my object in minutes despite no goto. Everything is mint, except I have zero confidence in the guiding now because of these issues. I have to sit and babysit the thing, and it slaughters any exposure time I have. I managed to gather about an hour and a half worth of data in almost three hours because of this nonsense.

 

I hope I've providing enough information here to help with trying to figure this out, this forum hasn't let me down yet when it has come to my incessant questions since I started last year and I'm hoping I can get some answers on what exactly is happening here! I appreciate any help, thanks in advance.

 

Here is the log...

 

PHD2_GuideLog_2021-07-03_232628.txt

 

[Clarkey]

I am far from an expert in PHD guiding, but looking at the log files (with my basic interpretation) it almost looks like the tracking stops and then PHD is desperately trying to get the mount back on track. Is there any way you mount was stopping or sticking that stopped the tracking? Obviously the mount you are using is relatively lightweight so any snagging might stop the tracking or if the balance is out slightly that might cause it.

I know I had some problems with the mount suddenly stopping which made everything go haywire - but that was an issue with EQMOD and a loose connection.

[Jay6879]

43 minutes ago, Clarkey said:

I am far from an expert in PHD guiding, but looking at the log files (with my basic interpretation) it almost looks like the tracking stops and then PHD is desperately trying to get the mount back on track. Is there any way you mount was stopping or sticking that stopped the tracking? Obviously the mount you are using is relatively lightweight so any snagging might stop the tracking or if the balance is out slightly that might cause it.

I know I had some problems with the mount suddenly stopping which made everything go haywire - but that was an issue with EQMOD and a loose connection.

 

I dont believe anything was stopping the mount, there is only a single 12v cable leaving the whole setup and the rest are fairly tidy. I originally thought it could be that but I had checked everything and it looked good. Not to mention the consistency of the drops being after 6 to 7 exposures each time I kinda ruled that out. Though I will definitely pay attention to cables next time.

Here is a screen grab from someone else who had a look at the log and it appears once the guiding goes wild there aren't even any pulses to correct it?

 

[Davey-T]

Excessive backlash or could be something come loose, maybe a grub screw on the worm drive.

You could try setting max move in RA to max allowed but all PHD does is keep ramping up the movement until something happens which looks like what it's doing.

Dave

[Adreneline]

3 hours ago, Jay6879 said:

I will get six to seven subs in and the RA guiding goes wild.

This is of no comfort to you - or help - but that has been exactly my experience with a CEM25-EC. Every so often the RA goes off on one for no apparent reason. I've tried numerous things/adjustments and watched lots of YouTube videos - helpful and contradictory - I've even tried three different guide scope - nothing has made any difference. Also had exactly the same problem with an original ASIair. The whole things is made all the worse if I attempt to introducing dithering into the mix. I've begun to think it is a conflict between the CEM25-EC and the ASIair.

At some stage I will try using a PC based setup and PHD2 to see if that works. 

I am following this thread with interest to see if anyone can shed light or help. Maybe you can seek solace in knowing you are not alone - well there's you and me at least.

 

 

[wimvb]

1 hour ago, Jay6879 said:

 

I dont believe anything was stopping the mount, there is only a single 12v cable leaving the whole setup and the rest are fairly tidy. I originally thought it could be that but I had checked everything and it looked good. Not to mention the consistency of the drops being after 6 to 7 exposures each time I kinda ruled that out. Though I will definitely pay attention to cables next time.

Here is a screen grab from someone else who had a look at the log and it appears once the guiding goes wild there aren't even any pulses to correct it?

 

I'm confused here. This image is not from your phd log file, because the equipment is a G11 mount connected with ASCOM, whereas in your original post you wrote that you use a star adventurer. And the guide log that you provided is for a star adventurer (ST4 port and only RA calibration).

Anyhow, when the guiding suddenly starts to wander off, it is usually a mechanical failure or cable snag.

[Jay6879]

2 hours ago, wimvb said:

I'm confused here. This image is not from your phd log file, because the equipment is a G11 mount connected with ASCOM, whereas in your original post you wrote that you use a star adventurer. And the guide log that you provided is for a star adventurer (ST4 port and only RA calibration).

Anyhow, when the guiding suddenly starts to wander off, it is usually a mechanical failure or cable snag.

 

Wtf for real? Someone else who said they took a look at the guide log shared that pic so I assumed that's what it was. Ugh.

So could a cable snag or mechanical failure cause issues that occur at consistent repeatable intervals like what has happened?

[Clarkey]

When I looked at the guide log it appeared to be trying to give a maximum 2000ms move (lines 371 up on the first log file) when the guiding went off. So PHD is 'seeing' the fault and trying to correct. This suggests to me that it is mechanical or a connection issue.

[Clarkey]

5 hours ago, Jay6879 said:

So could a cable snag or mechanical failure cause issues that occur at consistent repeatable intervals like what has happened?

No not really. But the interval between starting and failing is not the same on each log. It could be the mount sticking at a certain point in it's gear cycle. Have you checked the balance and weight of you set up. If the mount is near the limit of what it can carry / guide it is likely to be more of an issue.

I thought the ASI Air had built in guiding so you did not need to use PHD?

[JSeaman]

 

For the guiding, PHD has calculated 6.45 arc second per pixel, the calc is 206 x (3.8 u pixel size on the ASI 120 / 120mm Asi 30F4) 
For imagine, your APO has a 360mm focal length and it looks like a 4.3 u pixel size I think for the T3i which gives 206x(4.3/360) = 2.48 arc seconds per pixel

If we assume the guide scale should be no more than 4 times the size of the imaging scale then it should be OK

You are generally getting about +/- 5 arc seconds when the guiding is behaving

 

Note on the log at midnight, your corrections do pull it back in:

I would suggest increasing the maximum pulse beyond 2000mS to see if this is repeatable recovery

 

It seems you have no guiding in DEC:

Calibration step = phdlab_placeholder, Max RA duration = 2000, Max DEC duration = 2000, DEC guide mode = Off

Cal in RA only:

This results in a continual drift in dec and it is 10s of arc seconds:

 

Note also the pulses (bar graph bit) on the right hand side at the 2000mS limit, PHD is trying to correct but unable to make the mount behave. I would be checking how freely the mount moves and balance of equipment

[JSeaman]

Oh and your last log at 1:25 is interesting, no corrections being made and you get the RA runaway but it stops at about 20 arc seconds:

[wimvb]

9 minutes ago, JSeaman said:

It seems you have no guiding in DEC:

It’s a star adventurer, so no dec motor. This is ok in the settings.

20 minutes ago, Clarkey said:

It could be the mount sticking at a certain point in it's gear cycle.

According to the log, there are sections where guiding is fine during at least 1.5 worm cycles. If the mount gets stuck, it must be in the main RA wheel.

When this issue is resolved, there is still room for improvement, because the guiding shows a period of about 17 s, which is in the gear near the stepper motor.

27 minutes ago, Clarkey said:

I thought the ASI Air had built in guiding so you did not need to use PHD?

If the ASIAIR guider outputs a guidelog, the OP should try this guider and compare with phd.

The only conclusion I can draw so far is to check the mechanics: balance, clutch, cables, free movement. For the latter, with no load, release the clutch and spin the RA. It should move easily and not get stuck anywhere.

[wimvb]

26 minutes ago, JSeaman said:

That step in DEC is interesting. Something caused a sudden jump, even in RA. But guiding recovered. There is a smaller step earlier in the sequence. Even here, guiding took care of it. But it makes me wonder; how is the guidescope attached?

[JSeaman]

Thanks Wim, with the Dec drifting so much then alignment should be checked too I think

[Chefgage]

From the log it mentions dithering. Is this the case and if so have you tried it with the dithering turned off?

Edited July 7, 2021 by Chefgage

[michael8554]

14 hours ago, Jay6879 said:

I will get six to seven subs in and the RA guiding goes wild. I've seen it shoot up 50"! The star is completely lost.

You are ST4 guiding, which is fine in itself.

But means that unlike an ASCOM connection, your Guide Rates and RA/Dec positions aren't reported in the Logs, which makes diagnosing more difficult.

Your first Cal with a step of 2000ms gave 12 steps in the Cal, which in PHD2 would be correct, so stick with that.

You are only guiding in RA, so PA has to be good.

The logs report that PA Error is at least 5arcmins. Yes ASIAir is reporting only 2 arcmins, but that amount of drift is apparent in the logs.

That would be good enough if you were guiding Dec, not not good enough without.

So what is happening ?

You managed to guide for five sessions of 10 minutes or more, then RA went "wild".

I believe that during that period the guidestar has been horizontally central in the guide box, but the unguided Dec has been drifting vertically in the box, due to that PA Error.

Eventually Dec drifted vertically out of the box, and guiding failed.

There are flaws in this theory. In the log the Star Mass remains good, and often many RA corrections are being sent. Perhaps the Auto Select has move to another star ?

Despite that, it would be worth seeing what happens if you improve your PA, or stop/start guiding every 10 minutes or so, to reset the star position ?

IMO the sudden jump in Dec at 01:25 is an isolated event, not seen anywhere else.

Your image scale is 6.45arcsecs/pixel, it would be worth Binning X2 to reduce that to 3.27 and entering that into ASIAir.

RA guiding is very choppy, but lets see what guiding is like after these changes.

Michael

[wimvb]

1 hour ago, michael8554 said:

Your image scale is 6.45arcsecs/pixel, it would be worth Binning X2 to reduce that to 3.27 and entering that into ASIAir.

?

Binning has the effect of doubling the pixel scale (”/pixel), not dividing by 2.

[michael8554]

1 hour ago, wimvb said:

?

Binning has the effect of doubling the pixel scale (”/pixel), not dividing by 2.

Oops ! And a Beginner's mistake too !

Michael

 

[Jay6879]

9 hours ago, wimvb said:

That step in DEC is interesting. Something caused a sudden jump, even in RA. But guiding recovered. There is a smaller step earlier in the sequence. Even here, guiding took care of it. But it makes me wonder; how is the guidescope attached?

First off I want to thank all of you for joining in on solving this conundrum, as I said despite being very new to this I feel I've gotten everything down, and if guiding just worked properly I'd be on my way so thank you for the discussion here. I am going to read through the replies so far and respond as best I can. For now...

This isn't my image but it's essentially the way my guidescope is attached, using the provided rail on the Zenithstar 61.

 

[Jay6879]

9 hours ago, wimvb said:

It’s a star adventurer, so no dec motor. This is ok in the settings.

According to the log, there are sections where guiding is fine during at least 1.5 worm cycles. If the mount gets stuck, it must be in the main RA wheel.

When this issue is resolved, there is still room for improvement, because the guiding shows a period of about 17 s, which is in the gear near the stepper motor.

If the ASIAIR guider outputs a guidelog, the OP should try this guider and compare with phd.

The only conclusion I can draw so far is to check the mechanics: balance, clutch, cables, free movement. For the latter, with no load, release the clutch and spin the RA. It should move easily and not get stuck anywhere.

When you say it must be in the RA wheel, should I try tightening the clutch up more? I read somewhere that tightening too much would be detrimental so I would lightly tighten it. I will check the free movement tonight and will also experiment with my balancing setup...things that can be done while it is cloudy and rainy! 😞

 

 

7 hours ago, michael8554 said:

You are ST4 guiding, which is fine in itself.

But means that unlike an ASCOM connection, your Guide Rates and RA/Dec positions aren't reported in the Logs, which makes diagnosing more difficult.

Your first Cal with a step of 2000ms gave 12 steps in the Cal, which in PHD2 would be correct, so stick with that.

You are only guiding in RA, so PA has to be good.

The logs report that PA Error is at least 5arcmins. Yes ASIAir is reporting only 2 arcmins, but that amount of drift is apparent in the logs.

That would be good enough if you were guiding Dec, not not good enough without.

So what is happening ?

You managed to guide for five sessions of 10 minutes or more, then RA went "wild".

I believe that during that period the guidestar has been horizontally central in the guide box, but the unguided Dec has been drifting vertically in the box, due to that PA Error.

Eventually Dec drifted vertically out of the box, and guiding failed.

There are flaws in this theory. In the log the Star Mass remains good, and often many RA corrections are being sent. Perhaps the Auto Select has move to another star ?

Despite that, it would be worth seeing what happens if you improve your PA, or stop/start guiding every 10 minutes or so, to reset the star position ?

IMO the sudden jump in Dec at 01:25 is an isolated event, not seen anywhere else.

Your image scale is 6.45arcsecs/pixel, it would be worth Binning X2 to reduce that to 3.27 and entering that into ASIAir.

RA guiding is very choppy, but lets see what guiding is like after these changes.

Michael

There is declination drift despite the Asiair reporting 2 arc minutes...so would that mean it isnt to be trusted? Should I just try to get it even tighter? (1 arc minute? Not sure what happens below 1 arcminute ha)

 

[wimvb]

3 hours ago, Jay6879 said:

Should I just try to get it even tighter?

I would probably run the polar alignment procedure twice. That should get it close enough.

[JSeaman]

I don't think it's slip, if the clutch holds I'd leave it alone

From the graphs Dec is definitely drifting and quite a lot, definitely worth looking at polar alignment again

[Jay6879]

1 hour ago, wimvb said:

I would probably run the polar alignment procedure twice. That should get it close enough.

Ok I'll give that a go next time I'm out. So could the declination drift be the cause of these issues in your opinion? Like it drifts so much, and without any way to correct the drift, it eventually just fails?

If I remember correctly in the guide cam screen the little circle around the star would drift to the right.

[michael8554]

12 hours ago, Jay6879 said:

If I remember correctly in the guide cam screen the little circle around the star would drift to the right.

Depends on the rotation of the guidecam.

"to the right" could be Dec if the long side of the guidecam sensor is at 90 degrees.

[Jay6879]

2 hours ago, michael8554 said:

Depends on the rotation of the guidecam.

"to the right" could be Dec if the long side of the guidecam sensor is at 90 degrees.

The orientation of the camera matters as well! This is quite involved.l, a lot of variables.

For what it's worth this is the orientation of the guide camera from the other night...

 

Last night I set up the whole thingand played around with balance. What I had originally thought was well balanced I found needed to be tweaked more. I modified the counterbalance rod and added a bit more weight to the end, allowing me to adjust the counterweight that came with the Star Adventurer. It allowed me to get better balance than I did before, quite a bit better actually.

I tried rotating the Star Adventurer and either felt smooth the whole way. From what I'm gathering since it's showing Dec drift I'll tighten up PA and now I've got a much better balance. On top of that I'll manage the cords better to avoid snagging, hopefully tomorrow I'll be able to check if this has made a difference.

If you all don't mind I'll try to get a log at least as long as the one posted above to make a comparison? I do appreciate the help so far!