Odd behavior on feature tracking

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Earthless
Posts: 3
Joined: Tue Dec 14, 2021 7:37 am

Odd behavior on feature tracking

#1

Post by Earthless »

I'm trying to use feature tracking using an asi120mm connected via st4 to my cg5 mount. My scope is a c8.
I'm unable to pass the calibration stage, I receive the error "Failed due to incosistent angles".
I know that my mount suffers for some kind of backlash but what I see in the scatter graph is really strange, it seems that the mount first move in DEC instead of AR, then moves in AR: the result is a 90°angle. From the log I see it is moving XPositive and XNegative so I would expect something like a 180°.
Changing step size and required movement doesn't help.
Any idea?

Thanks
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admin
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Re: Odd behavior on feature tracking

#2

Post by admin »

Hi,

from the screenshot, it looks as though attempting to move the mount in the two directions on the RA axis has actually moved it in Dec then RA as you have noted. Two things seem possible

1) a bug in SharpCap's handling of the ST4 output for your camera
2) a crossed wire issue in the ST4 wiring (miswired cable, or a mount or camera not conforming to the specification). This could happen if you are using a cable that looks like an ST4 cable but is perhaps intended for another purpose with a different wiring pattern.

I suspect that you might find that if you use the arrow direction keys in the 'On Camera ST4' control in the 'Scope Controls' section, the opposite direction arrows will not move the mount in opposite directions. This doesn't really let us work out which of (1) and (2) is the problem, but it would pin the issue down to something to do with the ST4 movement directions, rather than a bug in the feature tracking code.

I did just test with my ASI120MM and can confirm that as far as I can tell the correct commands go through to the camera for the four guide directions using the arrow buttons. The only mount easily to hand to test with is a Celestron AltAZ SE mount - that doesn't respond in the way I would hope to the four directions of movement, but I wonder if it only really guides if in EQ mode (on a wedge) anyway.

cheers,

Robin
Earthless
Posts: 3
Joined: Tue Dec 14, 2021 7:37 am

Re: Odd behavior on feature tracking

#3

Post by Earthless »

Hi Robin, thanks for the answer.
I use the st4 cable that comes with camera however as soon as I can i will:
-try another camera (Asi 120mc) with its cable
-try the with the ascom driver connected to the mount (not using the st4 port)

I didn't see the scope control section, is it under setting -> hardware -> properties?

Thanks
Adriano
Earthless
Posts: 3
Joined: Tue Dec 14, 2021 7:37 am

Re: Odd behavior on feature tracking

#4

Post by Earthless »

I've found the scope control section.
I did the first test: try another camera (Asi 120mc) with its cable and it is seems to works fine.

It was cloudy so I just connect the camera and listen to the motors (to be more sure I simply unplugged the dec cable of the mount so moving in DEC wouldn't make any sound).
It seems like you said: my asi 120mm AR works with up and right direction, with asi120mc AR works with right and left direction.
It doesn't seems a cable problem since swapping the two cables doesn't change the behavior, I guess that is my asi120mm st4 port that is flawed I don't see other explanation. Really weird issue, sadly I need the asi120mm to guide and/or shoot the moon.
I'll try with ascom driver, this should totally bypass the camera.
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Re: Odd behavior on feature tracking

#5

Post by admin »

Hi,

if you don't mind a bit of electronics, you could probably build a cable that 'fixes' the output from the 120MM. I suspect that two or more of the output pins are swapped, which could be corrected with a custom made cable. Note that no noise from the mount might be OK if you are moving in -RA, since the ST4 guiding may just cancel out the normal tracking to make the mount stay still while the guiding pulse is active.

cheerse,

Robin
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