Mark Aston replied to the topic 'Tips for Auto-Focus' in the forum. 1 year ago

Hi All,

I changed over to running EKOS around a year ago and in that time I have not been able to run the focus module successfully with my 8” RC, standard crayford focuser and iOptron EF. I have reached the point where I have good steps in and out, use linear algorithm and get a ‘sort of’ V-curve. All setting seem to be about right for my setup and visually Autofocus seems to drive nicely out-of and back through focus.

My problem is that the module fails with ‘fail to detect a star’ when the image shows an annulus - this is even stepping outside a nominal focus by orders of 10s of steps. The annulus is bright and tracked in the green reticule, but EKOS seems to not track the outer diameter and maybe is attempting to measure part of the annulus rather than the whole.

I’m any case, it will only focus around 1 in 20 or more attempts and even then tweaking does better.

After browsing many discussions on focusing and probably missing the important one, I’m stumped! Can anyone point me in the right direction to track the outer diameter of an annulus for successful focusing?

Many thanks