[JJ_SO]

It oscillates around the proper position once, twice, even three times; sometimes it goes far away from the proper setting and returns only after a while. It doesn’t happen always, it doesn’t happen very often but, in our humble opinion, for an instrument of this class it happens definitely too often.

Hmm, reading this and after that watching the movie, I noticed the battery symbol went red and blinking. I don't know how much low batteries influence AF, but the AF drive of a lens this size needs to get some juice, I reckon'?