Thanks - I am also experimenting with this right now.

Actually, one simple ML modification would accomplish most of what I'm asking for: if at the end of calibration ML would print on the screen not just the median value, but the good interval as well. Then one can do any kind of calculations with these numbers.

I know the good interval is a function of the distance - but so is the median MA value as well, for many lenses. As a result, MA calibration is normally done at the typical distances the lens is used, hence the good interval information should still be valid.

The essence of my original point is that not just the median, but the whole MA interval information is valuable, and should not be discarded. The whole interval corresponds to MA values deemed "as good as it gets" by the AF system of the camera (or at the very least as "sufficiently good"). I'd expect this interval being wider at shortest FL of zoom lens (because of deeper DoF), and more narrow at the longer end (more shallow DoF). Using my approach to find the optimal MA value would take this DoF behaviour into account, and allow you to find the MA value where AF deviation from the perfect focus is comparable (in DoF units) at any focal length.

Here is actually another possibility - even more accurate way to find the optimal MA for a zoom which has different MA **and** different interval widths at the opposite FL ends perhaps would be to assume the interval width (or rather half-width) as a std (standard deviation), and the compute the optimal MA as a **weighted** average, using the standard formula:

<MA> = [MA1/(del1**2) + MA2/(del2**2)] / [1/del1**2 + 1/del2**2].

All these different approaches can be tested, if only ML could print the good MA range at the end of calibration.