Please ensure that the camera is using on the center AF point before concluding there is a problem in this regard. You may use any of the AF points provided by your camera, but only the center one will necessarily agree with the KatzEye™ prisms, since only the center AF point is sure to be pointed at the same object as the prisms. If there is still a problem using the center AF point, then it is likely that either the viewfinder or the camera’s AF system is miscalibrated. Please see here for more information on the subject or contact us for technical assistance.