More Like Wrong Ascension...EQ6-R Guiding/Tracking issues

[Rex Robichaux]

Hello everyone, 

 I recently returned from astrophotography after about a year hiatus...partially because of life/family/moving, and partly because I got fed up with my EQ6-R performance resulting in egg-shaped stars in most of my 60-300 second subs (at 750-900mm FL). Well, no surprise, the mounts performance issues are still there but I'm determined to find the culprit- and was hoping someone here might be able to help point me in the right direction. 

Although declination isn't perfect, it's acceptable for now, and on good calm, nights can be in the .5" RMS range. Right ascension on the other hand is all over the place but typically .9"-1.5", with large and sudden dips and jumps. Typically, RA performance tends to be worse when the scope is east-side, pointing west, but not always. Last night, it was actually performing worse when the scope was west side, pointing east. For the first year+ I had this mount, both axes were performing well (.4"-.7" consistently). I'm unsure what changed.

My Setup: 

Skywatcher EQ6-R

TSO 130mm APO

Primalucelab 60mm guidescope

Orion Starshoot Autoguider cam

QHY Polemaster

ST4 guiding

ASCOM telescrope control (GS Server, APT, PHD2)

I've ensured my tripod is level, and extremely sturdy through various reinforcements. I've experimented with various balancing (east-heavy, equal balance, west-heavy), and over a variety of seeing conditions, temperatures and nights. I performed a DIY hypertune a year and a half ago which really seemed to neither help, nor further hurt the performance. I also have tuned/adjusted backlash (particularly RA) until I'm blue in the face and (by feel at least) it's nice and tight right now without any binding. I also performed PPEC training via GS Server last night, but with PPEC on, I still didn't notice any large improvement in average RMS values. 

My debug and guide logs from last night can be found here: https://drive.google.com/file/d/15rhaa2LF5qIJj-jQtA_e1V3TLq-jChRX/view?usp=sharing

Last night's workflow was essentially hook up only the cables/gear necessary for guiding and:

• Polar align using QHY Polemaster for fairly accurate alignment
• Slew to the area around Spica 
• Perform calibration
• Run guiding assistant - record and apply values
• guide for a while, while monitoring performance (bad)
• Perform PPEC training and apply PPEC.
• Return to Home/park
• Slew to area around M81/M82
• Recalibrate in different part of the sky
• Perform guiding, while monitoring performance (better but not great)
• Perform PPEC training and apply PPEC.

Below are a few screenshots of what I observed:

Here are about 10 minutes of letting the guiding assistant run...you can probably spot the problem (or symptom at least)...

Here's the output of the guiding assistant once completed: 

Backlash Results:

Finally, after flipping, recalibrating (in a poor area of the sky), and re-guiding, things were looking at least a little better around M81/M82 facing (slightly) west:

I sure hope someone can bail me out of this one. I'm nearing the point of reaching out to OPT about their used trade-in program for this mount lol. 

Thanks for any/and all help and suggestions you can provide!

-Rex

[wave...@talktalk.net]

Hello Rex, the GuideLogs you iinked to are empty. You may have selected the wrong sessions.

The usual recommendation is to use the PHD2 uploader which lists the dates of your guiding runs and does it all automatically.

Cheers,

- Jack

[Rex Robichaux]

Hey Jack, 

 Woops sorry about that- just read up on the uploader...pretty nifty. The logs from last night should now be available here: https://openphdguiding.org/logs/dl/PHD2_logs_go6Y.zip

[Bruce Waddington]

Hi Rex.  I know you're trying to figure this thing out and are probably getting frustrated, but there's just too much flailing around here to support any solid diagnosis.  So try following this procedure:

https://www.dropbox.com/s/zrf0au7jaisvt85/How%20to%20create%20a%20baseline%20for%20guiding%20results%20using%20OpenPHD2.pdf?dl=0

1.  Start over with a new configuration profile using the new-profile-wizard.  Don't change any of the default guide algorithms or guiding parameters afterward

2.  Don't calibrate "in different parts of the sky" - get one good calibration near Dec = 0 and use it.  It looks like your mount has a massive amount of Dec backlash (reversal delay) so you will probably need to clear it manually before the calibration.  Just use the hand-controller to move the mount north (up-arrow) until you see the stars in the PHD2 display clearly moving.  The calibration you got in these log files looked fine so you shouldn't have any trouble getting another one.  With this much backlash, you must stick with the default guide algorithm in Dec.

3.  When you run the GA, let it measure the backlash again and apply only the changes it recommends.  If it squawks again about the guide camera focus, you should spend time to improve it.  That process requires some kind of measurement help, you can't just squint at the display.  You can use the PHD2 star profile tool, a Bahtinov focus mask, or an app like SharpCap to get critical focus.

4.  Do all of your testing near Dec=0 and within an hour or so of the celestial meridian, roughly the same area of the calibration.

5.  Use multi-star guiding always, don't try to pick a star manually. 

If you can get us some nice long guiding sessions from both sides of the pier, we can probably give you some advice.  Obviously, the Dec reversal delay will take some mechanical adjustment but that should be left until you have a more complete view of how the mount is performing in its current state.  Obviously, testing needs to be done with at least average seeing conditions.

Regards,

Bruce

[Rex Robichaux]

Hey Bruce- this is perfect. Thanks for taking the time to review the logs, and offer up some solid guidance. As soon as we get another clear night here (unfortunately...there aren't any in the extended forecast)- I'll give this all a shot and post my results. Thanks again for your time and input!

Best,

Rex