Not wanting to highjack this threat, but the DA 21mm I once had wobbled too. So much that, afraid it would fall apart, I finally send it in for repair.
It came back real tight, but it got tighter and tighter while in use, that on certain occasions the AF had trouble with it when going from close to infinity, not vice versa. It went back for repair and was replaced, the new one I got is wobbling too but somewhat lesser and the AF is flying.
I think that there is some wobbling needed to be sure that the AF (screw driven or not) will not be over stressed. To my humble opinion, there are two kinds of wobbling, one due to sluggish assembling and one on purpose for a smooth AF. The trouble is to identify the difference, time will tell....
Last edited by philippe; 01-23-2011 at 04:31 AM.