Today I continued testing the (auto) focus module with my Conon 600d and an artificial star.
First of all thank you, Jasem, for making the changes.
The focus in/out buttons are working now and the auto focus routine is operating, i.e. the focus position is being changed automatically according to the measured HFR.
Sometimes the algorithm reports to have successfully focused. However, when I crosscheck the result with a bahtinov-mask or by taking an image, in the majority of cases it turns out that the artificial star is not really focused.
With at least the smae frequency, the algorithm terminates unsuccessful, i.e. the algorithm‘s condition for „good focus reached“ could not be reached. In these cases, it was true that the image was not focussed.
If or if not the agorithm terminates successful in the sense of fulfilling the condition for „goog focus reached“ strongly depends on the iso, aperture and exposure time. This may have to do with saturation in the center of the stellar image, though the profiles never look saturated at all. Do the profiles really show the measured variation of flux along the stellar image? They rather look like a gaussian with the measured HFR...
Is it possible that the algorithm, which - I guess - is working fine for telescope focussers, cannot be applied to dslrs in the same way? In my tests, the algorithm often changed the step-size too really small steps long before the actual focus position had been reached and then iterated around a non-focus position. It also occured often that the focus direction changed though from the behaviour of the HFR one could easily see that it would rather be a good idea to move on in the same direction to keep HFR decreasing.
In the end, the autofocus algorithm not being reliable would‘t really bother me, if I could use either the DSLR live preview or the images taken in the focus module to adjust the the focus position manually with a bahtinov mask.
Unfortunatelly, when I try to do this, in the fits viewer the brightness is being auto-adjusted in a way that I can hardly see the bahtinov-spikes. In the live preview, the resolution is too low, and I don‘t find a way to adjust the brightness either, so I can‘t see the spikes properly in live preview either. If I set image transfer format to native (in the capture module), I can see the spikes but I cannot zoom in to magnify the star, so this does not seem to be a solution, either.
I finally did bahtinov focussing by disconnecting the dslr indi driver and connecting to the camera by dslr dashboard remote control on the Ipad. There the spikes are clearly visible in the live preview and I can find the focus position in no time. However, I would really like to be able to do the focussing within ekos.
I am almost sure that there must be a way to control the image brightness in the fits preview? Can anybody tell me, how bahtinov-focussing can be done within ekos?