Mark,

in the past, calibration was only available via the Celestron SCT driver. As I don't use a Celestron mount anymore, I can't say whether that's still the case.
Can you connect the focuser directly (via USB) to your computer and try that?

Cheers
Boris

It should not matter what is used to run the focuser calibration because the calibration data is stored in the focuser BUT it must be run AND it must be allowed to run to completion, Motor stopped after the return to the original position and all the focus calibration steps completed.

If you finish the focus run early, even after it has run to both stops, then the calibration data is not saved and you get the situation you are in with the limits both reading zero.

I don't allow the focuser to run without a good calibration on the advice of Celestron because if the focuser is driven into a hard stop at full power it can jam and may cause damage.

Chris,

quick question: are there any instructions on how to correctly configure backlash?

Quick reply; No.

Slightly longer, set a number try it. See what happens. Think about how you compensate for backlash when moving the focus knob by hand. SCTs tend to need a lot of correction, 500 is half a turn.

Thanks, Chris. Is 500 just an arbitrary number? Or in the ballpark of what you've been seeing? Just don't want to start my experiment in a completely wrong direction..

Actually, I think that was a stupid question. Half a turn sounds pretty huge.

Hi Boris,

I can get the calibration done by connecting the focuser direct to the laptop via usb and the celestron software. I was wondering if I could get the calibration done by Ekos.

Mark

Yes, using the Celestron SCT focuser driver. Connect the focuser using a USB cable and run the driver. There's a calibrate option somewhere.

Hi Chris,

And that doesn’t work because the min/max values are 0.

Cheers

I guess I'm a bit late, sorry ...

Anyway, as others have pointed out, I use the celestron_sct drivers, which means connecting a usb cable from the focuser directly to the PC, not through the handcontroller. When doing that, I get this INDI configuration window (in any INDI client program, like ccdciel, indistarter, ekos, etc...)



There's a button "Start Calibration" to activate the whole process. The button is still there in the latest INDI version (1.8.4), although I have't clicked it recently, since my focuser is still calibrated. But back when I did, I remember it solved my min-max limits being 0.

Kind regards,
James

Hi James,

No worries, weather is cloudy the coming week. So if I understand it correctly you have to calibrate the focuser via usb direct to the pc first and then connect it to a stellarmate. Then if you open Ekos the calibration can be done but you don’t have to because it has been calibrated beforehand. I asked the question because I got the idea that you could calibrate the focuser via stellarmate and Ekos directly.
Or am I mistaken in my assumptions?

Cheers,

Mark

the latest Celestron focus driver on stellarmate and ekos 3.4.3 on Mac crashes at the end of the calibration step, but it does work and does seem to achieve calibration despite the crash.