I just sold my Oly 17mm F2.8 and buyer just asked if the MF ring is supposed to turn (apparently it doesn't). I always used the 17mm on AF with the VF-1 so never really experimented with MF. I don't recall ever fiddling with the ring, so am embarrassed to say I don't recall if the MF ring ever did turn. Perspective from Oly 17 owners appreciated. thanks!