AM5 guiding issue, random RA instabilities

kaelig

Hello,
I use my AM5 mount since January 23 with a lot of pleasure.

Since the beginning of July, I have Ra spikes in guiding mode, it is random issues.
In the last nights, the issue become worst, I lost 20% of my images due to stroke on my
stars due to this issue (300s image with NBZ filter and ASI 2600MC).

I don't know what I must make: send back to ZWO for repairing?

Could you help me in order to solve this issue.

Thank you,
Micka

phd2-guidelog-2025-08-10-231830.txt

1MB

phd2-guidelog-2025-08-11-225556.txt

1MB

Tech@ZWO

Could you please try changing Minimum move = 0.100 to 0.200 and see if it works.

Tech@ZWO

From your logs, it seems there may be a periodic resonance issue. After you adjust the minimum move step, please check whether the guiding screws are properly tightened. May I ask if you are guiding using ASIAIR or PHD2?

kaelig

Tech@ZWO

Hello, thank you for your answer, I use an Asiair plus. I have looked in the Asiair interface, I have not found this parameter.
Could you indicate me the recommended parameters for guiding in the Asiair interface for 1s.
I will remake test as soon as the sky becomes clear. I will post here the result.
I wait your recommendations in order to help me.

Best regards,
Kaelig

kaelig

Tech@ZWO

Hello, thank you for your answer, I use an Asiair plus.

Here is the setup configurations:
Main setup: TS 80/450 (with the reducer), ASI2600MC temp=-5°C, draw filter, connection M63 > M54 > M48
Guiding setup: TS 50/200 with ASI 290MM mini, filter UV/IR cut
Guiding mode: X0,75, 1s, RA & DEC set to 50%

with:
filter Astronomik L2 2", imaging time: 60s
filter Optolong L-Pro 2", imaging time: 120s
filter IDAS NBZ 2", imaging time: 300s

We read so many advices on the forum, that is a little bit difficult to set the good values.

The guiding time is 1s by default, I increase to 1,5s in case of bad seeing (full moon)

The DEC agressivity is set to 50% most of the time (60s for 1,5s)

The RA agressivity is more difficult to set, more often 50%
=> Do I need to go to lower values in case of RA spikes?

The RA and Max Dec guides are set to the default values. In reading Zwo forum, I see I must decrease the values to 200-400ms range value. Is it possible to calculate the good range for these parameters?

What is the good range value for max guide pulse duration for RA and DEC?

I will remake test as soon as the sky becomes clear. I will post here the result.
I wait your recommendations if you could.

Best regards,
Kaelig

PS: due to ZWO is the owner of AM5, perhaps you could implement automatic calculation in order to set the guiding parameters in the good value ranges for this specific mount.

Tech@ZWO

It’s located in the Advanced Guiding Settings, at the very bottom. And 1s exposure time is appropriate.

retman

kaelig If you are using an AM5 then the default values for RA and Dec max duration guide rates should probably not be the default values. i have an AM3 and my values for Max RA and Dec are between 500msec and 600msec.
i have read that values of Max RA and Max Dec duration that are greater then the guiding exposure time (1 second in your case) tend to give correction pulses that exceed the exposure time so "contaminate" the next guiding exposure.
if the pulses are too great or too long then you have overshoot (instead of the pulse sending the dec or ra axis back to zero it "over shoots" (goes way past zero) and then oscillates for a while (this is what your graph looks like).
i use Minimum Move (Corrected Trigger Acc. of 0.1px...i would NOT change this until you first decrease the Max RA and Max Dec to much lower values. these values will always require some "tweeking" based on seeing conditions and your particular setup, but having them at the default is just too high (ie 2000msec...too high!)
i think the RA and Dec aggressiveness set to 50% is a good starting point. also, 1 second exposure time for guiding is also a good value for the AM mounts. (some folks use 0.5 sec, i have stayed at 1 second)
i hope that others on this forum will help you out, i've only been doing this for 2 years but this is what i have learned and what works for me.

kaelig

retman Thank you for your answer