See directly below for a more considered approach. Since in this example both calibration results are on the positive side and the lower value is +10, almost any positive calibration value would make the lens better at any focal length than it would have been at the default setting of 0. If we calibrate at 24mm with a result of +10 and at 70mm and get a result of +15. It’s easiest to explain this with a quick example (below). Whilst Reikan FoCal cannot address the lack of support in a camera for multiple microadjustment values, you can still calibrate a zoom lens and get a better result than an un-calibrated zoom. What you tend to find is the ideal auto-focus calibration value may vary between zoomed in and zoomed out, with the most difference seen at each of the zoom extremes. Most cameras only support a single micro-adjustment setting for the whole lens at all zoom positions.
