How can this guiding be improved? CEM60 and ASI120MM-mini

[Dewy Frank]

got an image of NGC 2237 I put together during a night of bad guiding. How did this happen? Is there an issue with the mount or settings? I think the seeing was "better than average".

[Dewy Frank]

more guide log info from the night.

[bw_m...@earthlink.net]

Please post the log files following the How to ask for help with PHD2  link.

 

Bruce

 

From: open-phd...@googlegroups.com <open-phd...@googlegroups.com> On Behalf Of Dewy Frank
Sent: Saturday, March 30, 2024 12:50 PM
To: Open PHD Guiding <open-phd...@googlegroups.com>
Subject: [open-phd-guiding] Re: How can this guiding be improved? CEM60 and ASI120MM-mini

 

more guide log info from the night.

On Saturday, March 30, 2024 at 3:44:21 PM UTC-4 Dewy Frank wrote:

got an image of NGC 2237 I put together during a night of bad guiding. How did this happen? Is there an issue with the mount or settings? I think the seeing was "better than average".

--
You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/f280b71f-494f-45fb-958c-1c145b6ba26bn%40googlegroups.com.

[Bruce Waddington]

Hi Dewy, unfortunately this is quite a mess.  In the future, please just post your PHD2 log files rather than spraying all these screen-shots into the forum - it's much more efficient.  It looks like your setup has some serious mechanical problems that are preventing decent guiding.  The problems are not caused by guiding, PHD2 is simply trying to wrestle with an out-of-control situation.  Here's one example of a failed calibration (RA in red):

You can see that the mount responded for the first few west guide commands then essentially froze after that.  A common reason for this is that you've got cable routing problems that are preventing the mount from moving freely.  Have you done a careful job of cable routing and made sure they can't drag, snag, or otherwise interfere with movement of the mount?  Another possible problem source is that the gear mesh on the mount axes is too tight and is causing binding.  We have seen this situation numerous times with freshly delivered iOptron mounts.

Once you finally got past this and got a usable calibration, the subsequent guiding sessions were very poor - here's just one example (RA in red, Dec in green):

You can see there are huge, abrupt excursions in both RA and Dec.  Since the Dec motor is normally idle, this again suggests you have either cable routing problems or your guiding assembly is moving around independently from the mount.  It only takes very small unwanted movement of the guide camera to create these problems - in your case, movement of less than 30 microns, about 1/2 the thickness of a human hair.  Beyond the huge excursions, you can also see the mount isn't responding well at all to guide corrections in Dec.

It sounds like you also need to sort out how the iOptron driver is working - you can't get reasonable guiding if the driver is changing guide speeds or otherwise exhibiting problems.  There are many, many iOptron users who guide effectively with PHD2 so maybe you should check in on a forum where you can get advice specific to your mount.

Good luck,

Bruce

[Dewy Frank]

https://openphdguiding.org/logs/dl/PHD2_logs_599g.zip

[Dewy Frank]

ok, I figured things are a mess with the mount, but what I don't know. But first, cables are not likely to be the issue, I'm a cable management freak. they are all routed, through nylon net cable sheathing, mounted, tied, and/or affixed in some way, there is only one cable that crosses the mount to tripod barrier. My z axis may be out of balance, but a very slight imbalance at that and doesn't seem to be able to be the cause of such chaotic guiding failure, right? So this is mechanical for sure? I guess I can start with the worm engagement. Though I set it as the manual states to do so, "fully engaged, then back off an eighth to quarter of a turn". 

here are my stars from last night. 3 minute exposures. 

On Sunday, March 31, 2024 at 6:26:41 PM UTC-4 Dewy Frank wrote:

https://openphdguiding.org/logs/dl/PHD2_logs_599g.zip

[bw_m...@earthlink.net]

Yes, thanks, we already got them.  They are what I used to analyze your situation. I was only emphasizing that the logs are all we need, not the screen-shots.

 

Bruce

 

From: open-phd...@googlegroups.com <open-phd...@googlegroups.com> On Behalf Of Dewy Frank
Sent: Sunday, March 31, 2024 3:27 PM
To: Open PHD Guiding <open-phd...@googlegroups.com>

Subject: Re: [open-phd-guiding] Re: How can this guiding be improved? CEM60 and ASI120MM-mini

 

https://openphdguiding.org/logs/dl/PHD2_logs_599g.zip

--
You received this message because you are subscribed to a topic in the Google Groups "Open PHD Guiding" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/open-phd-guiding/lKSs1jpPOeQ/unsubscribe.
To unsubscribe from this group and all its topics, send an email to open-phd-guidi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/13ffc63e-f425-4ecd-b0c8-13107de23c90n%40googlegroups.com.

[Brian Valente]

Dewy

Go back to Bruce's original response, which offered a number of details and suggestions. It sounds like the software and mount is not acting reliably nor predictably. 

On Mon, Apr 1, 2024 at 7:51 AM Dewy Frank <afsm...@gmail.com> wrote:

oh yes, I understand. Thank you for your help. 

Did you see the fourth calibration attempt @21:39:26 ? For some reason, the mount will fail to calibrate due to "stars not moving enough". But I restart iOptron or PHD2 and it will calibrate. I'm also confused about why it will guide ok for short periods, here  and there, like in the beginning and end of the 15min50sec session @ 22:02:12.

You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.

To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/c297f91b-711a-4344-b18f-a21c94709924n%40googlegroups.com.

--

Brian 

Brian Valente

astronomy portfolio https://www.astrobin.com/users/bvalente/ 

nature portfolio brianvalentephotography.com 

other astronomy https://www.brianvalentephotography.com/astrophotography/ 

[Dewy Frank]

almost 30 calibration attempts...star did not move enough....YYYY? 

Other than the usual suspects, i.e. not calibrating in appropriate areas of the sky, cable snag/drag, dead mount, mechanical failure, etc... 

What, in the PHD2 software, would cause the problem of: during calibration, the mount/stars moving as expected for 1, 2, or 3 steps, then just quit moving as expected(i.e. step1 - 1.8, step2 - 2.9, step3 - 4.6, step4 - 4.6, step5 - 4.7, step6 -4.5, step7 - 4.7, step8 - 4.6,.....step60 - 4.8...)??? Which is what is happening ,and is what I suspect is causing ALL of my guiding issues. 

for more context... read yesterday/today's posts     https://www.cloudynights.com/topic/916846-autoguiding-craziness-heeelp/

[Dewy Frank]

All issues have been resolved with a new cable(official iOptron endorsed USB-rs232-rs232-rj9)

Mount instantly calibrated, guided for 6 hours without error and 0.6"-1.0" the whole time. Yay, back to having fun again! lol.

[Brian Valente]

Thanks for the update Dewy

We appreciate that you took the time to post the fix, so others can benefit from your solution

--
You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/b6897830-50c0-4b1a-b4ae-2c6aadde619dn%40googlegroups.com.