any PHD2 log gurus out there?

[900SL]

Hi

 

I have an SXD2 with SB10 and guiding with Asi Air Pro

180mm guide scope and 178MM guide camera, pixel scale 2.75 arc sec/px guide  and 1.8 main scope

Dither set to 10 pixels on guide scope so 17 pixels main

Dither settings 3" for 5s, 40 sec timeout

Guide settings 2500ms DEC and RA duration

ASI set to 0.5 x sidereal guide rate BUT there is also a setting in the Starbook Ten for RA and DEC guide rate (from 0 - 99, default is 10 which apparently corresponds to 1.0x sidereal according to the excellent manual)

I'm getting timeouts on dither whereby the DEC doesn't recover in 40s, it seems to overshoot then slowly gets back on track, which might be related to the Starbook 10 settings?

 

NOTE I was all sky aligned so PA wasn't bang on, also target and guidescope was at 25 degrees

Welcome any feedback, example log attached

 

 

 

PHD2_GuideLog_2023-02-26_213256.txt

Edited February 27, 2023 by 900SL

[scotty38]

Is it a permanent setup? When did you last calibrate?

[Clarkey]

Looking at the trends PHD does seem to be doing what you are asking (10 pixels equating to about 25"). However, it seems to be struggling to return the declination back to normal. There is no declination backlash in the settings, so I am guessing this may be the problem.

Do you run the guiding assistant? It usually recommends a declination backlash setting.

[newbie alert]

10 minutes ago, Clarkey said:

Looking at the trends PHD does seem to be doing what you are asking (10 pixels equating to about 25"). However, it seems to be struggling to return the declination back to normal. There is no declination backlash in the settings, so I am guessing this may be the problem.

Do you run the guiding assistant? It usually recommends a declination backlash setting.

Don't think there's a guide assistant when using the air.... Don't think it uses the whole Phd package 

[Clarkey]

3 minutes ago, newbie alert said:

Don't think there's a guide assistant when using the air.... Don't think it uses the whole Phd package

Oops - my mistake. You are quite right.

Ignoring the guiding assistant bit, I think the declination backlash still looks like the culprit.

[900SL]

3 hours ago, scotty38 said:

Is it a permanent setup? When did you last calibrate?

Hi Scotty

 

No, I set up on a balcony. I calibrated before guiding. PA was likely not spot on as I was using all sky alignment facing SW, but guiding was fine. 

[900SL]

3 hours ago, Clarkey said:

Looking at the trends PHD does seem to be doing what you are asking (10 pixels equating to about 25"). However, it seems to be struggling to return the declination back to normal. There is no declination backlash in the settings, so I am guessing this may be the problem.

Do you run the guiding assistant? It usually recommends a declination backlash setting.

Thanks Clarkey

This log might be more useful, it has guide calibration data included. There seems to be some backlash on Dec, I noticed that north - south calibration takes a while to get back. I'm at 60 degrees north and a bit restricted on where I can calibrate

Full log is added as a text file

 

 

 

PHD2_GuideLog_2023-02-26_185852.txt

Edited February 27, 2023 by 900SL

[900SL]

2 hours ago, Clarkey said:

Oops - my mistake. You are quite right.

Ignoring the guiding assistant bit, I think the declination backlash still looks like the culprit.

Can I adjust guide settings to improve response to Dec backlash? I'm a bit of a novice and just finding my feet with ASi Air logs and the PHD2 implimentation

[Clarkey]

14 minutes ago, 900SL said:

I'm a bit of a novice and just finding my feet with ASi Air logs and the PHD2 implimentation

Sorry but I can't help with the PHD2 / ASI Air interface, not something I have experience of. In PHD you can set a backlash value in milliseconds so you could try adjusting it to see if things improve. On my HEQ5, when I have got it as good as I can this is still around 800 milliseconds. Can you run PHD2 independently of the ASI Air to allow you to measure the backlash?

[900SL]

Thanks Clarkey. I'll see if i can set it up.. I have PHD2 on a mini PC but not used it yet. Looks like it's time to dive in

[wimvb]

3 hours ago, 900SL said:

Looks like it's time to dive in

Definitely. The guiding assistant will most likely provide the answers you need. In the ASIAIR mount driver/dialog there may be an entry for backlash and whether it should be taken into account. At least that's the case for Ekos on which the Air is based.

[alacant]

Hi

Dither hits the mount hard and flings it a good way off the lock. DEC in particular struggles to recover. Wondering if you really need all that movement...

Reducing the dither may help, as would waiting longer for the dither to settle before beginning the next frame.

Otherwise like all mounts, there's only a limited amount software can do and it's a case of tearing apart, cleaning and lubricating followed by meticulous adjustment.

Cheers and HTH

 

Edited February 28, 2023 by alacant