Though the problems, I like the lens. What other lens you find better suited for that focal range to compliment the kit lens together for novice like me, with price consideration. The pentax k100d is my 1st dSLR and I am beginner and I may not be able to tell if something is really good or not. I wish I don't have the focus lock issue. With two days of test shots, I like what I see.
I have called up B&H photo and they can't tell if my problem is on the lens or the camera and I opt to return the lens with a RMA for defective lens.
If others also have these problems, please feel free to reply so that I can gather the information to decide if I should order the 2nd copy. It is likely that I may get another lemon. Or maybe this is a problem that should be ignored -- use AF.C, manual focus, 'ok to cancel AF' but that is not quite acceptable to me.
Thanks,
Hin