Astroart Forum

Hi guys
Just bought an Ascom compatible motor for my refractor focuser.I`ve downloaded and installed the specific Ascom driver for it from the Hitecastro web site. I notice on the MSB website it refers to the plugin `autofocus plugin for Astroart4` so I assume I don`t need it for AA5?. Trying with a simulated ccd image I can get to the autofocus part but not sure what to do with the `Step`, `Positions` or `Exposures` options?. Can`t seem to find any info online, for instance does AA5 find the best focus itself using FWHW??
Thanks
Steve

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Well think I`ve just answered my own question. Found a focuser simulator option and allowing AA5 to use its default 7 positions it displays a 4 digit focus reading for each position and goes to the best setting at the end!. Clever stuff will try it for real later
Steve

Hi,
the "STEP" depends by the hardware, most focusers have a range from 0..1000 to 0..50000, the step should be approx 1/100 of the range.
"POSITIONS" must be an odd number, for example with "7" the autofocus will take 3 exposure inside and 3 outside, moving the focuser by the "STEP" amount.
If the seeing is bad, it's recommended to use many "EXPOSURES" so that the focus value is evaluated better at every step.

The focus value is calculated from the shape of the star, but its value is not normalized (e.g. it increases with the exposure time) so one may think that it is the peak value. Obviously it's NOT the peak value, which would give very bad results.

Clear skies,
Fabio.