front focus - camera or lens problem

hi i got tamron 17-50 recently and found that is suffers front focusing badly. i had to use maximum vailable adjustment in k20d to get correct focus at 50mm but... now i get back focus at 17mm :/ i cannot set an adjustment that would fix all focal lengths. is it a camera o lens problem? my k20 works great with a kit lens.

Interesting.

I just got a Tamron 70-200 f2.8 and found it front focussed at 200mm and back focussed at 70mm, at about 135mm it was ok. I've only just sent it back, awaiting a replacement.

Wonder if it's a Tamron thing.... or something else.

Jeff

The recommendation for AF fine adjustment with a zoom is either to average the adjustment having checked at both ends and middle of the range, or to adjust for the focal length you use most.