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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

KStars focuser auto-selecting nebula or galaxy

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Hello,

I've been using KStars with Pegasus FocusCube v2 for 2 nights and I'm fighting KStars a lot.
If I use the scheduler, it forces the option "Auto Select Star" in the "Focuser" tab. Which leads to all the focusing not being able to converge.
The focuser module, moves the focus outward by a few thousands of steps and takes a picture. All stars are obviously blurred. The focuser module then decides that that galaxy or that nebula is the best star in the image. It adjusts the focus, and every other star comes into focus, but the galaxy/nebula remains blurry. The focuser module reports a failure.
Sometimes the initial outward focus is so large that the stars turn into very large circles. The focuser module finds a tiny bit of random noise and decides that this is the best star in the image. The big circles eventually turn into point-like stars, but the focuser module isn't interested, it keeps looking at that tiny bit of random noise in the image. For this specific problem reducing the initial step by 10x helped. However, if this initial step happens to be too small, the focuser module will not ever go further outward than the initial step.

Without the focuser device, I had moderate success in using the scheduler to image DSO unattanded. Now I got the auto-focuser device, and unattended imaging no longer seems feasible, as it requires constant babysitting.
Please tell me what am I doing wrong. How can I make an effective use of the auto-focuser to let the imaging run unattended?
2 years 3 weeks ago #81162

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I'm not an expert on this, others here are. I do have a FocusCube v2, which for me, now works pretty well. Success depends on matching the focus parameters to your scope setup.
Notes:
I had problems for a while with a loose coupler in my fcv2 attachment setup.
Pegasus suggested to me a backlash setting of 30.
Using SEP and a linear model, I use 40 as the step size and a multiplier of 3.5. with the medium star size option. My Esprit 120 mm and full frame Nikon Z7 tended to pick up portions of out-of-focus stars as individual stars unless I made sure it was restricted to stars > 1 pixel in size.
Here in the winter (Canada), if the scope hasn't acclimatized sufficiently, it can be an race to get a kstars focus completed (after a bhatinov mask initial focus) as the cooling scope will throw the focus off as it's doing the focus run.
I refocus on a change of 2 C temperature.

Cheers
Jerry
2 years 3 weeks ago #81163

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I am using full frame so it use stars from whole image. This should prevent that if it pick up galaxy as focus star other stars will override this. I had also issue that it become too out of focus so it started pick up noise as stars. Solution for this is decrease step size so they are not too out of focus. My in focus HFR is around 2.0 and I set step size to such value that first most out of focus HRF start around 7.
2 years 3 weeks ago #81176

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Thanks for the advice.

> with the medium star size option
Wow, I haven't even realized I can choose the star sizes.

Will try to adjust auto-focus settings as you, @nou and @Jerry Black, suggested. It seems that my step size is still much too large.
2 years 2 weeks ago #81245

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