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Mark,
I’ve spent hours and hours on both my EQ6-R mounts re balancing, minimising Dec and Ra backlash via the worm drive carrier and the drive motor belts and the lowest I can get down to according to the PHD2,Guiding Assistant is around 900ms
However this figure changes in different parts of the sky and under varying Sky conditions.
I wouldn’t pay too much attention to the backlash figures in the GA ( unless they are quite high + 2000ms ) I tend to analyse my guiding error numbers over a nights imaging from night to night
2 weeks ago on Thursday night my guiding was 1.25 to 1.50 arc sec see sawing all over the place ( obviously chasing the seeing ) pretty bad , then the next night 0.60 to 0.70 arc sec and really tight and stable. Conditions can change so much.
Since 2020 , I’ve changed from the Hysterisis algorithm to the predictive periodic error correction PPEC in PHD2 and found without any doubt that my overall guiding is not so much tighter, maybe slightly tighter ( as this is mostly dependent on prevailing conditions ) but more stable over a session.
Tuning and rebalancing my mounts has improved guiding by at least 20%
A backlash figure of 750ms is fine for your mount
At the end of the day the proof in the pudding is your images and whether your stars are nice and round and tight
One thing I’ve found again and again small tight stars are a result of excellent seeing and therefore good tight guiding
Bloated or fatter stars , but still round are a result of poor seeing and therefore poor guiding ( see sawing )
If your getting nice round tight stars with 5 min subs , don’t fiddle with your mount, I think it’s telling you I’m Ok.
Cheers
Martin
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