alastroct was not able to re-find the target star
ASIAIR does not use a single star during autofocusing. It uses an average HFD over multiple stars. The small inset image is just one of the stars that it uses (notice that the display jumps from star to star).
That being said, to form a V curve, ASIAIR has to start from a very defocused star. Typically with an HFD that is 10 or perhaps a bit more. Consider that a typical HFD is about 2 when a star is in focus, the defocused star's intensity is reduced by a factor of about 25.
I wouldn't be surprised that the failure you saw was caused by not enough signal for ASIAIR to find any defocused stars. Another possibility is that ASIAIR made too large a step, and exacerbates the problem by moving so much that the HFD is much larger even than 10.
By the way, I have tried ASIAIR on a single artificial star and it worked; so in your case, it probably didn't find a single defocussed star.
I know that for one of my OTA (Askar 200), where my EAF scale is 0.44 microns per EAF step, v1.5 ASIAIR produced too small of a step and ended up with a V-curve that was too shallow. So, there is an equal likelihood that it made too large a step in your case.
I would suggest raising the gain and/or the exposure time when doing autofocusing. I think ASIAIR will reject saturated stars when collecting HFD information, so there should not be a problem when some stars become saturated as they become more focused -- ASIAIR will simply pick other stars. I have already suggested implementing auto-exposure when focusing, and apparently it is already among their things to do for the future.
Chen
