EAF Settings

Looking  for recommendations on EAF settings for my Edge HD 8" with ASI Air. The autofocus curve I see is pretty shallow. I am currently using an AF step size  of 50. ( Backlash 0, min size 10, max size 100 of that matters)

I recently switched my EAF from my refractor to EdgeHD8. I still have the same setting that I used with my refractor. my step size (slow) is 10. 50 seems little large movement for me. I didn.t change my backlash (its still at 90) . Maybe reduce the AF step size to 5 or 10 and start what a backlash of 50 to see if you get tighter stars.

Much the same as Darrell suggested. Find out first what the best focus is in terms of FWHM or whatever measurement your system uses. Then run your autofocus and see if it matches it but in terms of star size and visual appearance. The only difference is I wouldn't bother with a mask, the human eye is very sensitive to small changes like this. Zoom way into a not super bright star and at high screen magnification. Also, don't forget that every optical system is going the have a zone of critical focus where tiny changes won't have any effect. That's the great thing and auto-focusing as why it works so well. Even though you might make 2 or 3 samples in that zone, it's the overall curve that pinpoints the best point right in the middle of the CFZ. Another indication that you're close is the number of detected stars in your image. When you are slightly off the very faintest stars will pretty much disappear so that can also be a good check. Seeing star images that are not round has nothing to do with focus.