Feature Tracking Calibration "Failed due to inconsistent scales from Axis X"

[admin]

Hi,

Ok, I can see in the log that for some reason the code that reduces the step size during calibration is activating again and again, making the steps smaller and smaller. That's not supposed to happen... It's only supposed to reduce the step size in the first step or so after the image actually starts moving (backlash taken up) if the image movement per step is large. Hopefully just a logic error that I can resolve.

The eventual failure is the old favourite of the movement directions due to Dec+ and Dec- movement not even being close to opposite each other. I am now wondering if the issue is that after RA- has finished, the mount will start tracking again, and the image will seem to drift while the backlash is being taken up - that drift will happen during the Dec+ calibration. I am going to try changing the order so the calibration is RA-, RA+ to see if that helps. Maybe even calibrate Dec first!

cheers,

Robin

[Borodog]

I installed the latest 4.1 beta. Feature tracking didn't work at all. Mostly didn't come close to the minimum 125 pixels I set last time. Was like it wasn't moving the RA axis at all. Eventually it failed with inconsistent scales from axis 0. The mount was perfectly responsive to the hand controller. I gave up and used PHD2, since I've installed a guide scope for polar alignment.

I really wish this worked.

GuidingLog_2022-12-02T21_25_38-7484.log

(32.29 KiB) Downloaded 48 times

[admin]

Hi,

looking at the log, it seems the same as the issue that I fixed in the code on Tuesday this week (after the latest release). If the image 'bounces' around, the code sees the movement each time and (wrongly) assumes it is a response to the mount movement, so it keeps reducing the amount of mount movement to try to compensate.

I've made a number of changes to minimize this problem (these will be in next weeks update)

1) The threshold for reducing the mount step size is scaled by the movement distance setting
2) The measurement on each frame is not how far it has moved from the last, instead how much further from the starting point it is than the last
3) The step size cannot drop below 50% of the initial step size (so it will never go down the the ridiculously small steps that show up in the log).

Additionally, I've fixed the order of calibration so that it does -RA, +RA then the Dec calibration - that should fix the RA continuing to drift due to backlash during the dec calibration which gives inconsistent angles.

cheers,

Robin

[Borodog]

Thanks, Robin.

For what it’s worth, there wasn’t really any wind last night. Not too much “bounce” was happening.

[Borodog]

Once again tonight I tried feature tracking. Once again it was barely moving the RA axis. There was no wind at all, my polar alignment was "excellent" this time, within 20". Jupiter was as steady (in position) as it is ever going to get on this mount in this scope.

I went back to PHD2. I do want to say that when PHD2 calibrates, if warns me that the axes are not orthogonal by 15 degrees, and that this could be poor polar alignment (not it), or DEC backlash (big fat yes). It only gives this warning with the 1100 EdgeHD, which, between the OTA, the optical train, the guide scope and camera, the DEC counterweight, and everything else, is pushing the payload limit of the CGEM. The C8, which weighs less than half as much, returns orthogonal axes. But even though it gives a warning, it guides just fine, at least for planetary imaging purposes anyway.

[Andreas83]

I hope I am correct here. I have now also tested the feature tracking and get the error: Failed due to inconsistent scales from Axis 0. Maybe the LOGs will help?
I use a Celestron AVX. This is connected to the computer with CPWI.
The camera is an Omegon veLox178M. Unfortunately I can't do it via On Camera ST4. It always says it's not connected.
Maybe the screenshots will help too. I tested it at the sun. This was as a full slice on the monitor. That's why I chose Center of Mass, but also Image Features.

THANKS a lot for helping.

Andreas

[admin]

Hi,

a couple of things that might help here

1) Try a higher movement rate - it looks like you are seeing different movement rates of the image for the two different directions and it's possible that a faster rate might help as it will minimize the effects of any offset between the two rates

2) Try SharpCap 4.1 beta - I made a lot of improvements in the calibration process a few months ago, but they are only in the 4.1 beta versions - they will not go into SharpCap 4.0

cheers,

Robin

[Andreas83]

Hi Robin,

many thanks for the reply.

Were can I change the movement rates?? You mean the movement Speed??

And I will try the betaversion. I didn't even realize there was a beta

THANKS

Andreas

[admin]

Hi,

yes, the dropdown at the top where you have selected 'Guiding Speed' - try 8x or 16x maybe? Also do try 4.1 as it fixes a number of issues that are present in 4.0

cheers,

Robin

[Andreas83]

4.1 is installed and now I`m waiting for the SUN.