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

[garyhawkins]

Hi all,

I can tell you PHD2 can have its issues as well. I'm currently struggling to get it going again after moving all my gear into an observatory. Currently trying to resolve a 'not enough movement in the RA axis' issue from PHD2.

That being said, featuring tracking with Sharpcap worked on the moon last night after rebalancing the mount. So, my question, "Can you use feature tracking for starfields?' As a photometrist, I use tracking more to keep the starfield in the OTA FOV through a 4-6hr run, rather than keeping the stars round (my exposure is 20-40sec most of the time). Starfield tracking working to the same degree of accuracy as moon tracking would be perfect.

Best regards,

Gary

[admin]

Hi Gary,

I've never tried it on star fields - I suspect that the calibration would be dreadfully slow (if it worked at all) because of the longer exposures needed to make then show up. To be honest, the best way to deal with that sort of drift is to use plate solving at intervals to recenter on the desired target. SharpCap 4.1 has this functionality integrated into the live stacking feature, so that if the drift exceeds a threshold (say 30 pixels), SharpCap will plate solve and correct the pointing to re-center the original target.

cheers,

Robin

[garyhawkins]

Hi Robin,

Thanks for alerting me to drift correction using plate solving in the livestacking routine. That would overcome the issue, in the event actual guiding failed.

Best regards,

Gary

PS: I've been doing thousands of flare star measurements in the last year, all using Sharpcap for capture and image calibration. It is working great for photometry capture.

[Andreas83]

Hi Robin,

I used the 4.1 version now, but I got this error:

Calibration Failed : Inconsistent angles of -89,8560441000491 and 129,82642385772905 from the two y measurements

And I cannot connect my Omegon via onCamera ST4. It only works with the Celestron CPWI.

With my ASI174 it works via ST4, but then there is the error.

[admin]

Hi,

SharpCap does not support controlling the ST4 port on the Omegon/ToupTek/RisingSky/etc cameras, so that is not unexpected.

The error about inconsistent angles is basically reporting that SharpCap tried moving the mount in opposite directions but the image didn't move in opposite directions as a result. This is happening on the declination calibration, so it probably means that the image is drifting in RA during the calibration process, meaning that the two directions are not opposite to each other.

Ideally the drift wouldn't happen, but sometimes using a faster movement rate helps as it means the dec calibration takes less time, so there is less drift.

cheers,

Robin

[Andreas83]

Thanks for the answer. I will test a faster movement rate.

[ctortolini]

I just throwed the towel trying to use feature tracking for solar... I really hope it gets better in the future but for now, I can't make it to work with none of my mounts (AM5, AZGTi, CEM70), so instead, I switched to this:

https://www.facebook.com/groups/1320781201963513

It is a PHD add-on that can track the sun, the moon or a planet... it works like a charm

Clear skies.

[c_future81]

Dear Robin,

I tried to take a picture of yesterdays Mars & Moon happening and sadly could never make use of the feature tracking option.
I recently switched to the new Skywatcher Wave 150i harmonic drive mount with which I happily switch to ALT AZ mode for Moon and planetary imaging. ("No" alignment needed, very much easier use of ADC corrector).

Previously in equatorial mode and with jupiter I could use the center of mass tracking suscessfully.

but this time in ALT AZ neither Jupiter or later Moon with feature tracking worked due "Failed due to inconsistent scales from Axis .." Errors.

I connect the mount in Sharpcap through the Skywather windows APP und there the mount is ofc launched in Alt Az mode with USB / Serial connection.

I'm I doing something wrong here or should any Alt Az setup work in general or is feature tracking only working in EQ mode?

by the way - seems with your last update from Feb. those out of memory errors are gone?

I attached 2 screenshots.

Screenshot 2025-02-09 193228.png (778.71 KiB) Viewed 1978 times

Screenshot 2025-02-09 194915.jpg (200.64 KiB) Viewed 1978 times

Hi Gary,

I've never tried it on star fields - I suspect that the calibration would be dreadfully slow (if it worked at all) because of the longer exposures needed to make then show up. To be honest, the best way to deal with that sort of drift is to use plate solving at intervals to recenter on the desired target. SharpCap 4.1 has this functionality integrated into the live stacking feature, so that if the drift exceeds a threshold (say 30 pixels), SharpCap will plate solve and correct the pointing to re-center the original target.

cheers,

Robin

[c_future81]

here are my logs from yesterday in Alt - AZ mode.

[c_future81]

Alright.. spend 3 hours outside today to analyze the problem.
I also did some screen record I will upload tomorrow.

So in short - tracking on RA just does not happen. I connect to the skywatcher 150i mount through the windows app in alt az Mode.

The Feature tracking calibration just didnt work because of the crazy image drift I have. With 16x it succeeded but constantly corrected the position of the object while guiding.

I also recognized that if I slew manually horizontally with guiding speed, the drift just stopped.

I set back everything to home position disconnected the mount and used the skywatcher app on my mobile via WiFi and in the end that worked... I could not control the mount via Sharpcap that way but I still had some minutes (not seconds as before) I manually had to do some slight framing correction (at 1600 focal length and aps-c sensor)

This is very confusing.. will try to contact skywatcher about it.