Quote Originally Posted by another view
I have the 28-80 f2.8 and it also has this ring (you've got this one too I think). I hated it when I got it because I did the same thing a couple of times. Actually I bumped it and didn't realize that it was in manual focus right away - thought not crossing my mind right away because I wasn't using it.

After awhile you get used to it - I suppose I'd rather not have that option than have it the way it is (better yet a switch on the side), but at this point I don't think it would keep me from buying one of their lenses.

I also have the 28-80 and the ring is much easier to work than my copy of the 12-24. I love the optical and build quality(of 12-24), but I have to take the camera and focus ring in a very firm grip, and sometimes change my grip on the ring to move it. Of course I can't keep the cam up to my eye when I do this.
The Sigma design seems like it'd be easier to live with.
MO,
Mark.