Guiding Consistency

[Chris Pendred]

Hi

I’m getting mixed results from tracking using phd2. Sometimes it’s good. Sometimes it’s not so good and I’m finding only about 30% of my light frames are good quality (no trailing).

Amongst the logs for 14 feb 2026 which I have provided the link to below, number 5 for  19 mins shows consistent guiding within 0.75” which I’m happy with.

However number 6 just afterwards is plus or minus 5”. It’s lost the good results and even after 10 minutes it hasn’t settled to the good results I just had.

How can i get more consistent results ?

I have tried a couple of different Dec options. My dec backlash came back as 3300ms. I’ve heard it’s an idea to polar align west by 10 minutes of arc and use the south only direction for Dec guiding (or is it north ?). Is this a recommended approach when you have poor Dec backlash ? I have adjusted the worm meshing as best I can.

I have tried using the guiding assistant  as part of setup for each imaging session. But for some reason the results I get at any session seems to be pot luck.

Also when I look at the live tracking for the guiding points only update about once every 15 to 30 seconds. I’ve seen YouTube videos where the points update every second or so. How do I change this ?

Any advice would be appreciated. 

https://openphdguiding.org/logs/dl/PHD2_logs_BrcS.zip

[al.mcl...@gmail.com]

While we wait for the experts (I am not one) a couple of things which may help them are some details of your rig.  

The log profile says 'guidescope' , but what mount?  

DEC guiding is turned off, there is probably a good reason for this, but it would help to know what it is.  

The guidescope focal length is set as 400 mm, is this correct?  

The last calibration was 20 January which may be fine if this is a permanent set-up (is it?), but it might be worth a recalibration, even so.  

HTH

al mcl

[Chris Pendred]

Hi

The mount is  skywatcher NEQ6 Pro.

I did have Dec guiding on and the guiding assistant measured 3300ms backlash. I so got the same kind of mixed results. I just turned it off to see if the results changed.

The guidescope  is 400mm fl. Its an orion shortube 80

I’m wondering if settling time is having an impact but it’s just a guess

Hope this helps

Sent from my iPhone

On 17 Feb 2026, at 6:08 pm, al.mcl...@gmail.com <al.mcl...@gmail.com> wrote:

While we wait for the experts (I am not one) a couple of things which may help them are some details of your rig.  

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[al.mcl...@gmail.com]

Settling time only comes into play after a dither and there don't seem to be any in the various runs in the log file, so it may be a case of looking elsewhere?

On Tuesday, February 17, 2026 at 11:27:06 AM UTC chris.p wrote:

Hi

The mount is  skywatcher NEQ6 Pro.

I did have Dec guiding on and the guiding assistant measured 3300ms backlash. I so got the same kind of mixed results. I just turned it off to see if the results changed.

The guidescope  is 400mm fl. Its an orion shortube 80

I’m wondering if settling time is having an impact but it’s just a guess

Hope this helps

Sent from my iPhone

On 17 Feb 2026, at 6:08 pm, al.mcl wrote:

While we wait for the experts (I am not one) a couple of things which may help them are some details of your rig.  

The log profile says 'guidescope' , but what mount?  

DEC guiding is turned off, there is probably a good reason for this, but it would help to know what it is.  

The guidescope focal length is set as 400 mm, is this correct?  

The last calibration was 20 January which may be fine if this is a permanent set-up (is it?), but it might be worth a recalibration, even so.  

HTH

al mcl

On Tuesday, February 17, 2026 at 5:53:39 AM UTC chris.p wrote:

Hi

I’m getting mixed results from tracking using phd2. Sometimes it’s good. Sometimes it’s not so good and I’m finding only about 30% of my light frames are good quality (no trailing).

Amongst the logs for 14 feb 2026 which I have provided the link to below, number 5 for  19 mins shows consistent guiding within 0.75” which I’m happy with.

However number 6 just afterwards is plus or minus 5”. It’s lost the good results and even after 10 minutes it hasn’t settled to the good results I just had.

How can i get more consistent results ?

I have tried a couple of different Dec options. My dec backlash came back as 3300ms. I’ve heard it’s an idea to polar align west by 10 minutes of arc and use the south only direction for Dec guiding (or is it north ?). Is this a recommended approach when you have poor Dec backlash ? I have adjusted the worm meshing as best I can.

I have tried using the guiding assistant  as part of setup for each imaging session. But for some reason the results I get at any session seems to be pot luck.

Also when I look at the live tracking for the guiding points only update about once every 15 to 30 seconds. I’ve seen YouTube videos where the points update every second or so. How do I change this ?

Any advice would be appreciated. 

https://openphdguiding.org/logs/dl/PHD2_logs_BrcS.zip

[Chris Pendred]

Hi

I've uploaded another set of logs which shows dithering  during  Nina sequence

https://openphdguiding.org/logs/dl/PHD2_logs_PSP3.zip

Thanks for your help

Cheers

Chris

[Bruce Waddington]

You've definitely got a very strange situation here.  I think the critical point is your observation that the real-time display is only updating every 15+ seconds.  That observation is correct and that's the first problem to address.  It isn't a display or a PHD2 problem, it's an indication that you're only getting a fresh guide camera image every 15+ seconds and your mount isn't nearly accurate enough to go that long between corrections.  Normally, PHD2 would be showing alerts that these 2-second exposures are taking too long to complete, but I don't see that.  What I do see is that you seem to be using a OneDrive folder as a repository for all the log files and probably all of the main camera images.  If this means that all of this data is being streamed real-time to a cloud storage service, that's a really bad idea.  So the first thing is to stop doing that - store all your astro-related real-time data in a folder on the local PC.  When the imaging session is complete, then you can migrate those files to a cloud store if that's what you need to do.   It will be easy to see if this fixes the problem - just run PHD2 by itself, start looping 2-sec exposures on a star field, and watch the display to see if it's updating quickly.  Until this problem is resolved, you won't get anywhere with guiding.  By the way, what kind of PC are you using for all this?

Once the timing problem is fixed, follow the procedures in the attached document to get a measurement baseline of how well your mount tracks.  Also, fix the saturation setting in PHD2 - you're using a 16-bit camera but you've defined the saturation level (Saturation ADU) as 255, a value appropriate for an 8-bit camera.  You need a setting of around 65500.  Actually, if you create a new profile for testing using the new-profile-wizard, this should get fixed for you.  Don't mess around with any of the PHD2 parameters in the new profile.  Leave Dec guiding active, run the Calibration Assistant while following all its directions, then run the GA.  Let the GA re-do the backlash test so we can see that.  I would also extend the directions in the baseline document by doing 20-min guiding sessions on both sides of the pier rather than just one.  Naturally, all of this must be done without an imaging/session manager app running - just PHD2.

Good luck,

Bruce

[Brian Valente]

>>>> What I do see is that you seem to be using a OneDrive folder as a repository for all the log files and probably all of the main camera images.  If this means that all of this data is being streamed real-time to a cloud storage service, that's a really bad idea.  So the first thing is to stop doing that 

unless you are using OneDrive, I recommend you disable it completely (and uninstall if possible). that will address this issue

To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/4e1a6c91-e264-42f1-a841-c092b0faf895n%40googlegroups.com.

--

Brian 

Brian Valente

astronomy portfolio https://www.astrobin.com/users/bvalente/ 

[Chris Pendred]

Hi guys

Thank you for all the advice. I will definitely run through all the steps and make the changes you have advised.

With my qhy5ii camera i have noticed that if i try to take a 2 second image with nina it does take a long time (maybe 15 seconds) before the image appears. Maybe i should just use 8 bit from the start. Or maybe the camera is too old and i need a new one. I did find something in the camera manual about using a different camera driver selection so i might try that also. Hopefully running the wizard will fix it as you say

The pc is a Mele quieter 4C 

I’ll let you know how i go but might be a few days.

Thanks again

Sent from my iPhone

On 18 Feb 2026, at 12:41 am, Brian Valente <bval...@gmail.com> wrote:



To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/CAJa45i4prKzAOKPjbAcz4SNGWuF0_sqUAQ%2Bd9RKj0aJpx6d4Vg%40mail.gmail.com.

[Brian Valente]

I have a QHY5II mono camera, it works fine, so I don't think a camera swap is needed only because of age/model .

you might just work on getting the camera to respond within a reasonable amount of time. you can do this during the daytime

To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/D32D801C-2E7E-40BA-BBDF-1388C8622EBC%40gmail.com.

[Bruce Waddington]

@Chris:  I saw another problem in your guide log that relates to a long-standing problem with the GSServer mount driver.  I didn't bring it up because it isn't relevant to your most important problem.  However, I'm now in touch with one of the developers of the mount driver and he was unaware of the problem.  Assuming that it happens again on your system, we can probably get it fixed if you can also capture the log that is generated by the mount driver itself.  Do you know about that and where it's located on your system?  If you don't, I can probably get additional instructions on that.  The problem is the underlying reason for the PHD2 alerts that "pulse guiding has failed", an alert you've chosen to disable.

Regards,

Bruce

[Chris Pendred]

Hi Bruce. I wasn’t aware. If you could send me some instructions as to what i need to do that would be great.

Thanks

Chris

Sent from my iPhone

On 19 Feb 2026, at 2:45 am, Bruce Waddington <bw_m...@earthlink.net> wrote:



To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/a436a669-dbb2-46b0-bd3e-b26186a9a648n%40googlegroups.com.