Poor guiding graph on EQ6-R PRO

[Luca Bartolucci]

Hello everyone,

First of all, I’d like to thank those who helped me last year with my first post about the guiding issue with my Bresser. Since November 2025, I managed to buy a new SkyWatcher EQ6-R PRO mount, keeping the following equipment: RC 6” telescope, off-axis guider, Canon EOS 700D as imaging camera, and ASI 120MM Mini as guide camera.
I’m writing again because I need help — I can’t seem to get a decent guiding graph in PHD2 to take satisfying photos. Since I got this new mount, I’ve never been able to get a decent graph.
At first I thought it might be the polar alignment not being accurate, then I moved on to balancing the DEC axis, but nothing worked. In particular, during my last sessions at the end of February, I achieved a really good DEC balance by adding a small counterweight on one side of the telescope.
Below you’ll find a link to the PHD2 log file:

https://openphdguiding.org/logs/dl/PHD2_logs_uFXw.zip. 

I’ve shared multiple guiding sessions along with the related Guide Assistant reports. I’ve also tried adjusting several parameters such as hysteresis, aggressiveness, minimum move, and calibration step size.

In your opinion, should I send it in for service to have it maintained?

Thank you in advance for your help!
Best regards.

[Michael Waring]

1.  You probably have the "EQMOD ASCOM Pulseguide setting" on the default setting, which is too low:

"RA Guide Speed = 1.5 a-s/s, Dec Guide Speed = 1.5 a-s/s"

Needs to be at least 7.5arcsec/sec.

Don't alter the PHD2 Calibration Step Size once you've corrected the EQMOD setting, 

You may need to create a new Equipment Profile to regain the correct setting.

2.  "GA Result - Recommendation: Backlash is >= 19128 ms; you may need to guide in only one Dec direction (currently Sud)"

Dec worm needs adjusting.

Michael

Wiltshire UK

[Frederic Ruciak]

Hi, I had an EQ6R Pro and the guiding improved a lot once properly tuned (consistently 0.4 to 0.6" RMS ). You have two categories of issues: everything related to the guiding itself (eqmod, PHD2, calibration, parameters settings, ...) that I will not comment besides the expert of the group, (I'm an old guy I read the manual and everything related to eqmod extensively). And you have the  mechanical tuning of the EQ6R. On my own I dismounted it and changed all the bearings but it is not necessary to get 80 to 90% of the benefits. First of all you you have to check if your mount is moving smoothly on both axis. When balanced withou clampling RA or DEC, the axis have to move smoothly withou any effort, just a small push is sufficient to trigger a wide rotation. If not your mount has been delivered with too much torque on the axis compressing the bearings. This is almost systematic from SW. There are plenty of good tutorials on youtube like the ones of astrobloke or this one https://www.youtube.com/watch?v=0yzFTjlpZaI&t=472s. The second main thing to tune is the backlash for the DEC axis. This video  https://www.youtube.com/watch?v=rEgkPA-Cd84&t=1858s is very clear you do not need to dismount but the way to test that there is no blockiing point is very good. That way you can achieve the least backlash without blockiing point. When you tune the little screws that adjust the backlash you have to do very small move (1/16 of a turn) and be patient. It is worth to do it. On my mount these adjustements made a HUGE difference.

Hope this helps.

CS Frédéric

[Bruce Waddington]

Things would go better for you if you followed best practices and used the Calibration Assistant.  Follow all of its instructions especially increasing the guide speed setting in the mount driver to 0.9x sidereal.  Because this guide speed setting is so low, there's really not much we can tell you about the mount, including the huge apparent backlash.  It also seems that your guide camera was picking up only a single guide star, so I don't know if that's because of poor guide camera focus or poor skies.  Certainly, that guide camera is perfectly capable of getting better results and should be picking up multiple guide stars most of the time.  I think you should abandon your bad-pixel map and use a newly created dark library to get this sorted out.

Good luck,

Bruce

[Luca Bartolucci]

Hello everyone,

I want to thank all of you for your advice and promptness in replying. I wanted to wait before responding because I wanted to test your suggestions first.
I tried to fix the backlash on both RA and DEC. Through the Guide Assistant, I was able to verify that the backlash has decreased significantly, which is already a relief. I then tried setting the recommended speeds of 0.7 on both DEC and RA through EQMOD, and I reinstalled PHD2, but the graph shows no signs of improvement. Below I am attaching the PHD2 log file and the photo of M13 that I obtained, which I think looks good anyway (a stack of 30 frames at 5 minutes and 17 at 60 seconds). I would also like to get your opinion on the photo, please.

log phd2: https://openphdguiding.org/logs/dl/PHD2_logs_rgFV.zip

Thank you very much.

[Brian Valente]

Hi Luca

One of the main things I see is a 10 second uncorrected error in your RA, which is the constraint to your RA axis guiding. It varies in amplitude from 0.5-0.3" but you can see below it sticks out when looking at the residual (uncorrected) error:

This is a mechanical issue and is typically somewhere in the gearbox/motor

I'm not sure why you re-did calibration so often, and why you're changing the step size?  The first calibration seemed fine, so don't know what you are hoping to gain there.

RA is typically higher than dec, but dec backlash is still a factor. When you get RA tamed, i suggest you enable dec auto backlash compensation, maybe start around 250ms value

Yours is a classic M13 image, nothing to complain about there. 

Brian

--
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 visit https://groups.google.com/d/msgid/open-phd-guiding/361a2760-5734-4875-9485-645f6ee6bb84n%40googlegroups.com.

--

Brian 

Brian Valente

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

[Luca Bartolucci]

Thank you so much for your help.

What I try to do is have an RMS of about 0.5 - 0.6", because during the session it always gives me a very high error.