hello
I am using a ED AF NIKKOR 80-200mm 1:2.8 D for portraits with my D90 and mostly a tripod . the lens ( or the camera ?) often doesnt focus as accurate as i expect...i am aware there are different quality of lenses out there.maybe my copy is just not great...? sometimes i get better results then other times... or... i have heard that the camera might need some kind of calibration to optimize the lens focus ...
does anybody have some advice...

thanks a lot
regards
weiwuwei