ASIAIR PLus Autoguiding a CEM70EC2 Mount

SFn8CieR

The Encoders on my new Ioptron CEM70EC2 Mount cannot be turned off as far as I know. I have been using 2 or 3 secs for Guiding Exposure time, so its bumping the mount too often. From what I understand the Encoders reduce the Mounts PE so it runs accurately and the Guiding Software should only occasionally bump the Mount where needed to keep it in line, someone previously mentioned that using a longer guide exposure makes a lot of sense.

Also what calibration Step and MAX RA and DEC Duration figures should I use on the ASIAIR's Mount setup page?
The current ASIAIR defaults are 2000, 2000, 2000 and I have read that if you are using a ZWO mini Guide scope with FL=120mm these figures should be in the vicinity of 8000 to 10000? I know when you do a calibration, these higher values move the mount more than if you use the default 2000 values and requires less Steps to calibrate. However if you are using an OAG with the FL of the Guider being the same as the FL of the scope, then these figures should be in the range of 250 to 500ms. I would be interested to know your thoughts on all of this.

Also when guiding, what aggression values should I use? I would presume using lower figures such as 10 to 25% would keep the autoguiding bumps down to a minimum? Also with the Guiding Rate, should I try different values 0.25, 0.5, 0.75 x Siderial to see which gives better RMS values or just leave it at 50%?

I forgot to mention that I am currently using a SW ED72 Scope with native focal length, with ZWO guidescope and camera, and once I have sorted out autoguiding my double encoder mount with this setup, I will try autoguiding my C11 with 0.63 Reducer and OAG, so autoguiding will be more critical then.
thanks.
Nick

SFn8CieR

Hello anyone there to answer please?

alastroct

It isn't clear from your post what issues you are experiencing. Posting a guide log here may shed some light.

I don't have a CEM70EC2 but do have a CEM70, so any advice here may not be useful. PHD2 recommends guide rates in the range of .5 - 1.0 sidereal. I'd suggest trying to increase your aggression values; mine are usually around 50% - 70%. Calibration step size shouldn't be an issue if you are actually completing calibration.

You will generally get better guiding with an OAG than a separate guide scope. If you have one I'd suggest trying that, since it removes several variables.

SFn8CieR

I have tried both aggressive and non aggresive settings but not getting a definitive result. I have attached my Logs as requested so please chime in with any comments. cheers Nick

phd2-guidelog-2023-11-05-204347.txt

367kB

alastroct

Your polar alignment is way off, between 6.5 and 17 and worsening through the night. How are you aligning? Are you using the ASIAir polar alignment tool? Is your mount on a solid surface?

I assume that without good alignment the encoders and guiding will be fighting with each other.

However, overall, your guiding isn't that bad, around .5 RMS. You can probably get better from that mount however.

SFn8CieR

My mount is on a permanent pier in my observatory.
Yes I did a polar alignment with AA+ and got it very close, within a few seconds for RA & Dec.
I did notice that when I tightened up the screws that the numbers changed a bit, but not much.
So how can you tell my PA is way off and you say that it is it changing during the night? How can you tell that?
I think I need to do the PA again and double check as I cannot understand why it has moved.
Also you say my guiding is OK at 0.5 rms, where did you find that?
cheers and thanks..
Nick

alastroct

I loaded your log file into this application that analyzes phd2 log files:

https://openphdguiding.org/phd2-log-viewer/

SFn8CieR

Yes I use phd2 log viewer too but I am not sure exactly what I am looking at to identify any problems.
How can you tell my PA is no good and changing during the night? If the RA & DEC graphs run parallel and not on a slope then PA looks ok I would have thought? Also how did you get 0.5rms out of all of that?
many thanks
Nick