Changing the Guiding Rate on AM5

mikenoname

Per Chen's recommendation, last night I decided to try and change the guiding rate in my mount to 0.25 sidereal and was apparently unable to do so.

I went into the ASI Mount program on my PC (I do not run ASIAir or any apps), went to the Advanced panel and changed the Guiding Rate setting to 0.25. I then created a new hardware profile in PHD2 specifying a guiding rate of 0.25 and then ran a calibration. You can see the result that I got in the image below. PHD2 still reports RA and declination guiding rate of 0.5.

No matter what I did, I was never able to get PHD2 to acknowledge the new guiding rate. Am I doing something wrong?

Has anyone successfully changed the guiding rate on their AM5?

w7ay

mikenoname No matter what I did, I was never able to get PHD2 to acknowledge the new guiding rate. Am I doing something wrong?

Ah, it is in the manual.

See

https://openphdguiding.org/man-dev/Advanced_settings.htm

In bold letters, it says:

Note: changing the guide speed setting here never changes the guide speed setting in the mount - that can only be done via the mount driver or the hand-controller.

Chen

w7ay

mikenoname I do not run ASIAir or any apps

Have you tried one of the programs inside ASIstudio? It should run on any macOS or Windows PC. There is a guide rate menu in the mount interface of ASIimg, for example. See if that works.

Who knows, your mount may never have properly implemented different guide rates.

Chen

mikenoname

I should also add that I am using the original release versions of the ASCOM driver and 1.1.2 firmware.

mikenoname

w7ay

Which is why I said that I changed it in the ASI Mount program on the PC (the ASCOM driver) first before creating the new hardware profile in PHD2.

Mike

mikenoname

Yeah, I'm wondering if it is some kind of bug in the ASI Mount driver where changing the setting has no effect. But before I can jump to that conclusion, I need to confirm that I'm not the only one experiencing the issue.

Another thing that I noticed last night while trying to change the guide rate setting is that the guiding rate box has a drop-down that allows you to select a guide rate, but those guide rates are only in increments of 0.1. In other words, 0.25 is not an option. The box does seem to allow you to type stuff in, so I manually typed in 0.25, which seems to not work. I might go set up tonight and try an experiment to pick one of the preset drop-down selections and see if that sticks. Perhaps it doesn't like typed-in data…

w7ay

mikenoname In other words, 0.25 is not an option.

I have mentioned it a number of times, do not blindly copy my settings.

Look at the slope of your mount and determine what is the slowest guide rate your mount can tolerate. 0.25x sidereal is a good number for my mount (an RST-135; and it may not be optimal for some other RST-135 either, much less a ZWO mount). Yours might be 0.2, 0.3 or 0.4; who knows. Measure first, then set the number.

If you make the guide rate too small for your mount, you will eventually see the flat top comb as guide pulses when your mount hits the places where the slope is the greatest -- that is when the rate is too low to keep up with the slope of the periodic error.

Chen

KC_Astro_Mutt

Hi Mike. That must be the one thing that works fine on my AM5. Whatever I set the guide rate to, PHD2 sees it and applies it. Although, I've only selected the available selections in the pulldown. Never tried custom input. Maybe if all else fails mine, I'll start fiddling with that. The gurus at PHD2 say the higher the better, but I think they have a lot to learn about strain wave mounts. I've generally gone higher than 0.5, never lower. Maybe that would be worth trying.

mikenoname

Thanks for that, Jeff. Very encouraging that I will at least be able to change the rate and have it stick. Hopefully I will be able to get out tonight and tinker...