Getting backlash under control

[Gary Siegel]

Beautiful cool night to focus on polar aligning my Celestron Evolution 8 and Pro HD wedge. It took me 3 hours but after 2 ASPA (All Star Polar alignment) in CPWI and another polar alignment in PHD2 (Drift Align) I think I got it with my total RMS under 1 (.83). PHD2 does a better job with Polar alignment than CPWI.   My calibration Dec and RA lines are perpendicular (first time).  

The problem I'm having is that I can't seem to get my backlash under control. Guiding Assistant says "my mount never established consistent south moves".   I'm not sure what to do.  Has anyone experience an issue similar?

P.S.  I meant to change my exposure back to 2 seconds after running guiding assistant.  It was set to 1 second when I was using the Drift Align tool.  

Thanks everyone.

- Gary

https://openphdguiding.org/logs/dl/PHD2_logs_EVoU.zip

 

[Brian Valente]

Hi Gary

backlash is a common issue/concern. It's a common warning but there are features and techniques to deal with it.

In your case let's look at the last guide run

There was some initial stiction in your Dec at the start (Dec in red), so if I remove that from the analysis, you can see RA and Dec are actually quite close. So in general it's not an issue for you.... yet

Dec backlash is a non-issue in this specific run because your polar alignment was enough misaligned that Dec guiding only happened in one direction, so there isn't any backlash present in your guided output. You csn see here all the guide pulses (the lines going up) are all on one side

That does point to the need to improve your polar alignment which the GA run also alerted you on. Once that is done, you may experience Dec backlash. Enabling auto backlash compensation will help here

--
You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/5f5b9e59-b241-40df-88ee-a26f72ed5b38n%40googlegroups.com.

--

Brian 

Brian Valente

astro portfolio https://www.brianvalentephotography.com/astrophotography/

portfolio brianvalentephotography.com 

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

[gmsie...@gmail.com]

Thank you Brian for looking at my log.  You certainly need to be patient when running Drift Align (rerunning it every time I set up).  I enabling auto backlash compensation and will try again the next clear night. Will this help correct the backlash results as shown in Guiding Assistant?

 

 

Regards,
 
Gary Siegel
M: 860.466.9582
_____________________________
Together
Everyone
Achieves
More

 

We're at our best when we work together!

 

From: open-phd...@googlegroups.com <open-phd...@googlegroups.com> On Behalf Of Brian Valente
Sent: Monday, July 11, 2022 10:17 AM
To: Open PHD Guiding <open-phd...@googlegroups.com>
Subject: Re: [open-phd-guiding] Getting backlash under control

 

Hi Gary

 

backlash is a common issue/concern. It's a common warning but there are features and techniques to deal with it.

 

In your case let's look at the last guide run

 

 

There was some initial stiction in your Dec at the start (Dec in red), so if I remove that from the analysis, you can see RA and Dec are actually quite close. So in general it's not an issue for you.... yet

 

Dec backlash is a non-issue in this specific run because your polar alignment was enough misaligned that Dec guiding only happened in one direction, so there isn't any backlash present in your guided output. You csn see here all the guide pulses (the lines going up) are all on one side

 

 

That does point to the need to improve your polar alignment which the GA run also alerted you on. Once that is done, you may experience Dec backlash. Enabling auto backlash compensation will help here

 

On Mon, Jul 11, 2022 at 6:26 AM Gary Siegel <gmsie...@gmail.com> wrote:

Beautiful cool night to focus on polar aligning my Celestron Evolution 8 and Pro HD wedge. It took me 3 hours but after 2 ASPA (All Star Polar alignment) in CPWI and another polar alignment in PHD2 (Drift Align) I think I got it with my total RMS under 1 (.83). PHD2 does a better job with Polar alignment than CPWI.   My calibration Dec and RA lines are perpendicular (first time).  

The problem I'm having is that I can't seem to get my backlash under control. Guiding Assistant says "my mount never established consistent south moves".   I'm not sure what to do.  Has anyone experience an issue similar?

 

P.S.  I meant to change my exposure back to 2 seconds after running guiding assistant.  It was set to 1 second when I was using the Drift Align tool.  

 

Thanks everyone.

 

- Gary

 

 

https://openphdguiding.org/logs/dl/PHD2_logs_EVoU.zip

 

 

 

 

--
You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/5f5b9e59-b241-40df-88ee-a26f72ed5b38n%40googlegroups.com.

 

--

Brian 

 

 

 

Brian Valente

astro portfolio https://www.brianvalentephotography.com/astrophotography/

portfolio brianvalentephotography.com 

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

--
You received this message because you are subscribed to a topic in the Google Groups "Open PHD Guiding" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/open-phd-guiding/1e7YOmOPx7k/unsubscribe.
To unsubscribe from this group and all its topics, send an email to open-phd-guidi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/CAJa45i49O_1eeBR1JQ%3Dok8RP5nE1qkgiUy9EWLxTPiLPTa-2Dw%40mail.gmail.com.

[Brian Valente]

>>>  I enabling auto backlash compensation and will try again the next clear night. Will this help correct the backlash results as shown in Guiding Assistant?

No, you will still get those messages

From your graph it looks like a mechanical issue.

However, my point was this: looking at your guiding and additional tools available to you to manage your backlash, you may not need to do anything to get good results.

The jury is still out because of your polar misalignment resulted in no Dec reversals, so we don't yet know how much of an issue it can be

Looking at your attached graph, it could be a problem but let's see what happens.

Brian

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/00fa01d8953e%245a3a49b0%240eaedd10%24%40gmail.com.

[gmsie...@gmail.com]

Just to be certain, are these yellow circles (on the Stellarium map) the correct location to aim for when using Drift Align?  I live in a heavily wooded area and my view of the celestial equator is limited with pockets of open sky.  Thanks

 

 

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/CAJa45i5vJ1k49%3Deb_vFhC0w53xuhPBcY7iNPWAu8q9Fif55E1Q%40mail.gmail.com.

[Bruce Waddington]

What does the blue arc represent?  The celestial equator?  If so, those are the recommended pointing positions.

Bruce

[Brian Valente]

Yes that looks like the celestial equator 

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/307ee8ca-c63e-4c0a-bfd3-0d63814ceaaen%40googlegroups.com.

[gmsie...@gmail.com]

Yes celestial equator. That’s what I believe Stellarium means by “Equator”.  Thanks everyone.

 

 

Regards,
 
Gary Siegel
M: 860.466.9582
_____________________________
Together
Everyone
Achieves
More

 

We're at our best when we work together!

 

From: open-phd...@googlegroups.com <open-phd...@googlegroups.com> On Behalf Of Bruce Waddington
Sent: Friday, July 15, 2022 9:09 PM
To: Open PHD Guiding <open-phd...@googlegroups.com>
Subject: Re: [open-phd-guiding] Getting backlash under control

 

What does the blue arc represent?  The celestial equator?  If so, those are the recommended pointing positions.

 

Bruce

 

On Thursday, July 14, 2022 at 1:57:42 PM UTC-7 gmsie...@gmail.com wrote:

Just to be certain, are these yellow circles (on the Stellarium map) the correct location to aim for when using Drift Align?  I live in a heavily wooded area and my view of the celestial equator is limited with pockets of open sky.  Thanks

 

 

 

There was some initial stiction in your Dec at the start (Dec in red), so if I remove that from the analysis, you can see RA and Dec are actually quite close. So in general it's not an issue for you.... yet

 

Dec backlash is a non-issue in this specific run because your polar alignment was enough misaligned that Dec guiding only happened in one direction, so there isn't any backlash present in your guided output. You csn see here all the guide pulses (the lines going up) are all on one side

 

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/307ee8ca-c63e-4c0a-bfd3-0d63814ceaaen%40googlegroups.com.