It’s a marvel how today’s lenses and cameras achieve auto-focusing, some better than others, of course. A lot goes into these designs. If you grew up with manual focus lenses, you may recall how some were easier to use with smoother movements. A sticky focusing lens was garbage, even if its optical elements were good, right?
LensRentals posted on their blog a discussion of how lens designers have implemented different approaches to non-manual focusing or, focusing with electromagnetic motors. You know you have one of these because you can turn the focusing ring without getting that tactile feedback that the older manual lenses gave.
So, who’s up to taking your lenses apart to see what you have? 😉
No! No! No! …just kidding.