Edit: After posting this comment, I searched through the forums and can see that this is a complex subject with a lot of different solutions, none of which are perfect. I at least know where to start.
After reading the comments, I'm more confused than ever. How can a photographer determine if the lens or the camera is causing a focus problem? I am not familiar with FoCal -- is this a company that tested the camera/lens combo for you? Last, does anyone know how it could occur that the lens does not focus on target, as in my mind the camera senses the focus and sends signals to the lens until the lens is properly focussed. I am especially curious since I am considering a purchase of the 24-70, but am reading of focus problems. At $1900, I would expect it to be virtually perfect. I'm concerned I won't know how to identify and diagnose a problem within the return period. Thanks to anyone who responds.