I recently bought a used 16-3L II and it seemed soft at first. After a quick AFMA, Focal suggested +12/13 on both ends. It was tested under very good lighting conditions(+15EV) and on a stable tripod. That AFMA made it a lot better though. But do these extreme values imply something is seriously wrong with the lens and need to be checked/calibrated?
if I sell a lens, I don't want someone with an xti complaining I sold them a bad lens because they can't do afma.
Very good point..... Return it.