[netrex]

Have you considered that the camera might be at fault for some of your focus problems? I mean since it happens to so many of your lenses. I have the K-5 with a 50-135mm (which I owned before, sold, traded back later against the 60-250mm+money to get f/2.8 again), 16-50mm and had the 60-250mm before, and I don't have any problems like this. I had a problem with the 16-50mm (which is the second one of these lenses I've owned, sold the first due to finances, it did not have these problems), but I sent it in for a fix, and now it's good. They also worked as they should on my K-x and K10D.



I say this cause it seems odd that you have problem with so many lenses, that it might be the camera that is at fault, or maybe somewhat at fault.