Autoguiding Issues - Forums

Topic starter

Oct 21, 2022 · Edited: Oct 21, 2022

I didn't realize that cutting and pasting from Word would cause formatting problems...

Hi,
I am hoping that you can help me with autoguiding issues that I have been experiencing. Normally, my autoguiding is consistently good, with values about 0.6" to 0.9". However, my last two sessions I have been getting large errors in the declination axis. The errors in the declination axis appear to slowly oscillate between 30" and 40" peak-to-peak, if not larger. I have no idea if my issue is related to ASIAIR software or mount hardware issues.

My setup is as follows:
Skywatcher HEQ5 Pro mount (does not have Rowan belt mod)
WO SpaceCat51 telescope
ASIAIR Pro
ASI120MM mini guide camera
120mm guidescope
ASI183MC Pro main camera
Jackery Explorer 300 power station

I have tried rebooting the ASIAIR, checking cable connections, and varying the aggression and duration without much effect. I will note that I made very minor adjustments to the set screws in the declination axis to eliminate backlash prior to my problems occurring, but I checked afterwards and exercised the mount head a full 360 degress and did not detect any strange noises or signs of binding. I am not sure if that is a coincidence, or in some way related to my autoguiding errors, which started afterwards. I have also noted the mount making a "chirp" or clicking sound every now and then.

Not sure if it is helpful, but I attached the guide log from my last session PHD2_GuideLog_2022-10-15_203800.txt

Hoping someone has experience with this issue because I am stuck until I resolve this.

Thanks,
Jim

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Michael Ring

Oct 21, 2022 · Edited: Oct 21, 2022

The clicking is exactly the effect I had when I did try to remove the backlash and created a little binding.
So your best bet will be to undo your changes to DEC.
When checking for binding later you will also have to do a full 360 degrees rotation of the Dec axis as you already did.

A good indication that you have overdone the adjustment is to manually rotate the gears of the axis that you try to adjust, it is easy to feel with your fingers when you have overdone the job. Ideally you go to the position where sound changes or you hear binding, turn off the mount (important!!!) and adjust by checking when the gears start to move without the need to apply much force.

When you cannot hear binding then slew to the same Dec pos where you saw Bad guiding and compare if there is a difference when you move RA or DeC gears.

Michael

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Patrick

Oct 21, 2022

I second Michael Ring’s response, based on my own experiences with my EQ6R and it taking two attempts to get the adjustment right. After my first try the quiding was much worse than before, as you are experiencing. The second attempt was far better , after backing off the worm gear, as I had introduced mild binding. I’m now at around .4 arc seconds with reasonable seeing. It doesn’t take a lot of binding to have dramatic effects on tracking. There is an extremely fine line between having good gear engagement and binding. I found that listening to the pitch of the sound when doing a fast slew was effective. I would suggest doing the slew with the normal setup of equipment and correctly balanced. I assume you have watched some of the YouTube videos on this.

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AstroCapture325

Topic starter

Oct 21, 2022

Michael and Patrick,

Thanks for the suggestions! I will work on re-adjusting the declination axis this afternoon and hopefully try out tonight. I will keep the group posted on my results.

Jim

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AstroCapture325

Topic starter

Oct 22, 2022

It worked!
Before I did any adjustments I tried rotating the declination gears manually. I had introduced so much binding that I could not even rotate the DEC gear. After I backed off the worm gear I did a manual rotation and everything was smooth and easy to rotate. I took it for a test run last night against the Veil nebula and was very pleased. My tracking errors were between 0.6 - 0.9 arc seconds, which is the historical performance of my mount.

Thanks again for the help Michael and Patrick!

Jim

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