Upload & Sell: Off
I'm not familiar with that test rig of yours but where is your focus point...is it the line where the little arrows are pointing to? If so, it's possible the actual AF point is picking up the signature just below it and skewing the results. That's why I hate these (and similar) focus test rigs as it's too easy to misplace the focus point. Focusing should always be on a completely flat area that is absolutely 90 degrees perpendicular to the camera/lens in both axis. When you introduce an angle that is too close to the area of focus, it could effect the focusing and invalidate the results.