Originally Posted by Timbuctoo 
I did some basic stats. So far there are 16 posts on the 16-50mm lens. 9 have been good versions and 7 have been bad. That works out to being;
Good = 56.25%
Bad = 43.75%
So far that's not really good enough for a lense worth the amount it's selling for even if the lense has been specifically calibrated to function as specified on the K20D because most of us still use the K10D.
I'd really like to get both the SDM lenses but as far as this lense is concerned I'll wait till the good verses bad ratio looks a bit better. I might give it a crack when the % of good lenses reaches 70%. Keep posting because it helps to get accurate results.
Tim H
The DA*50-135 has been widely reported as a good lens. I tested three of them, all are pretty good. My newly purchased one is good on both K10D and K20D.
As to the DA16-50, the majority problem is the BF problem at the wide end on K10D camera, but mine works fine on the new K20D camera (while pretty bad on K10D, probably the worst among the 3 I've used). I've seen similar report (by Wim from Netherlands) on DPR. But seems some guys have problem focusing on the infinity w/ the DA1650 and K20D combo too ...