Don't know but it's well documented on Nikon forums by users. Also when I first got my D80 I played around with a Tamron 17-50 and it snapped into focus quickly.
When the new ones came out and I was looking to buy another lens I tried at Adorama a couple of new Tamron 17-50's and the focus felt slow and the motor made some weird clicking sounds.
Tamron's have great optics. But the AF motor on the Nikon's is slow and makes really cheap sounding noises. That's too bad. Hopefully some of the new upcoming Tamron lenses will uses a new an improve AF motor.
Well, weird clicking sounds does not sound good at all! And I wonder where a clicking sound would come from since there was no mechanical connection between the camera and the AF motor. Strange indeed. I wonder if Tamron hasn't already addressed the issue? Have they been accepting returns for it?
