Wont Dither Using SharpCap Pro :-(

[gol...@charter.net]

Hi All,

 

Hopefully someone has an idea on why I am not able to dither using SharpCap pro.

 

I have a Celestron AVX mount that I am using and the first time I was not able to dither, I also was not able to calibrate due to excessive backlash in DEC.   I went and physically adjusted the hardware worm gears and so on to minimize the issue.   Last night the 18^th was the first time I was able to get out with clear skies and try the system out after adjustments.

 

For the connection between PHD2 & the Mount I am using the latest CPWI software to connect and control the mount.   I choose CPWI ASCOM for the mount connection and I use the same connection for SharpCap.   All software was updated to the most current production releases.  

 

My process last night was to run a calibration which was successful although there was a warning about the ratio between the PA and Dec predicted results.  Begins at 2020-04-18 22:25:24 (prior to that I was going thru the manual and reading different things and the system was on and off many times for various reasons)

 

I then slewed to my first target and started guiding and dithering worked.  This shows up in the log at Guiding Begins at 2020-04-18 22:32:21.  Link to guide logs at the end of the email.

 

I then slewed to the next target and then I started to get the message in SharpCap;

• Dither Status: Cannot dither- PHD@ is not settled – currently Settling
• note I did not have any messages in PHD2.
• PHD2 Status:  Guiding
• Settle Status:  Settling: 2.1px for 0.0/2 0s.  

All these status messages are shown in the screen shot of the SharpCap guiding screen shot.

 

For the settings of SharpCap, they were modified as I to see if I could change something to get it work.  So if there is something way out of line I was making adjustments and turning guiding off and on in SharpCap to see if it would settle.

 

In summary originally the first time I used PHD2 guiding dithering was working.   The second night out I had the issue with the failed calibrations due to large DEC backlash which gave me a logical reason why it failed so I worked on the hardware.   Then tonight the first time being used after the HW adjustments and after a new calibration it dithering worked for one target.  After slewing to the second target of the evening  I received the message in SharpCap about settling, so is it a SharpCap bug,  a parameter issues that I don’t know about or a PHD2 setting or am I using the wrong guiding algorithms. 

 

Hopefully someone has already found the solution to this and can give me some advice.   I don’t get much observing time in Michigan due to cloudy conditions so when I do get out I want to have all the tools in the toolbox working.

 

https://openphdguiding.org/logs/dl/PHD2_logs_YjsD.zip

 

 

~73
Don
KD8NNU
2014 3905CC Top Gun :-)
5 miles from Downtown Hell MI as the crow fly’s
-.- -.. ---.. -. -. ..-

 

[Brian Valente]

Hi Don

you have quite a lot going on here, it appears not just one thing that's causing you headaches. 

as you may know sharpcap controls the dither amount and settling, PHD just does the dither and reports back the values. 

your situation suggests your dither is failing because the guidestar is not getting under your settle criteria. however, other than your one run (segment 3 starting at 22:33) i don't see any dither commands being sent to PHD. And it looks like your pixel resolution combined with mount performance should still get this under your criteria. 

here's your run with successful dithering, you can see the dithers:

here's a subsequent run, no dither commands that I see:

Here are some symptoms/issues i see and suggest:

- I would avoid the CPWI driver for now. there have been many users reporting that it does not work reliably at the moment for guiding. use the ascom driver. that alone may clear this up.

- i see a number of aborted runs where the DEC seems to run amok: here's one example. is this the case where your dec is not responsive?

- your polar alignment appears to be significantly off. look at the dec axis here, almost all of your corrections are on one side:

- i didn't see a guiding assistant run which would have pointed this out. If you haven't already done so, i'd recommend doing a baseline guiding, to make sure you have your settings basically correct.  details are here: https://www.dropbox.com/s/os1thorvswmzaul/How%20to%20create%20a%20baseline%20for%20guiding%20results%20using%20OpenPHD2.pdf?dl=0 

without getting too much into your mount performance, I see you are using PPEC, but at this point i think you should stick with the default setup. It appears your RA periodic error is quite high (20"+) which of course explains why you might do that, but at this point your DEC seems to be your limiting factor. 

it almost certainly will ask you to do things you've already done, but it's best to start with a clean slate, following those steps. it helps isolate what are the issues.

--
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/007901d61650%2469b877a0%243d2966e0%24%40charter.net.

--

Brian 

Brian Valente

portfolio brianvalentephotography.com 

[gol...@charter.net]

Hi Brian,

 

Thank you for the quick reply.  

 

By starting a new wizard will that also change the algorithms back to the defaults?   If not what should I be using for RA & DEC controls.

 

I will also try per your suggestion to use ASCOM and not use CPWI. 

 

Plus I will recheck my polar alignment, I wonder if I bumped my mount in the cheap observatory I built.

 

~73
Don
KD8NNU
2014 3905CC Top Gun :-)
5 miles from Downtown Hell MI as the crow fly’s
-.- -.. ---.. -. -. ..-

 

From: open-phd...@googlegroups.com <open-phd...@googlegroups.com> On Behalf Of Brian Valente
Sent: Sunday, April 19, 2020 11:32 AM
To: Open PHD Guiding <open-phd...@googlegroups.com>
Subject: Re: [open-phd-guiding] Wont Dither Using SharpCap Pro :-(

 

Hi Don

 

you have quite a lot going on here, it appears not just one thing that's causing you headaches. 

 

as you may know sharpcap controls the dither amount and settling, PHD just does the dither and reports back the values. 

 

your situation suggests your dither is failing because the guidestar is not getting under your settle criteria. however, other than your one run (segment 3 starting at 22:33) i don't see any dither commands being sent to PHD. And it looks like your pixel resolution combined with mount performance should still get this under your criteria. 

 

here's your run with successful dithering, you can see the dithers:

 

here's a subsequent run, no dither commands that I see:

 

Here are some symptoms/issues i see and suggest:

 

- I would avoid the CPWI driver for now. there have been many users reporting that it does not work reliably at the moment for guiding. use the ascom driver. that alone may clear this up.

 

- i see a number of aborted runs where the DEC seems to run amok: here's one example. is this the case where your dec is not responsive?

 

- your polar alignment appears to be significantly off. look at the dec axis here, almost all of your corrections are on one side:

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/CAJa45i6qywgPWpH5gbPsLGjocwqLTV3k60dG8M3AfhY9XAxsXQ%40mail.gmail.com.

[Brian Valente]

Yes for now I’d stick with the defaults. Get a baseline and go from there. Don’t change any values while you are doing this even though it’s tempting

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/010b01d61676%2424ba9d10%246e2fd730%24%40charter.net.