Hi Ron, what settings are you using for Initial Step size and Out Step Multiple?
I understand your point, that during the autofocus procedure the set of stars in "full field" is changing. Sometimes happens that small portion of a star ,that is too much out of focus, is identified as a small star, with small HFR. This then can lead to incorrect calculation of average HFR of stars in "full field". At least this happens to me sometimes.
Now I have discovered that I have better results if I use Step size = 200 instead of 300, which I used to have before. It is also good to set the Out Step Multiple setting to be half of number of typical iteration in first focusing run, eg: if the first automatic focus procedure takes 13 iterations (from right to left of the chart), I am setting the Out Step Multiple to 6. So the best focus should be somewhere in the middle of the V-curve.
All of this applies to Iterative algortihm

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