We recently purchased a D4s and found tons of back focus issues. We sent both the lens and the body into the shop to find out which was the problem and the report came back that both pieces of equipment were fine. We sent it back to Nikon and they checked it out and said nothing came up but they would replace the body. We received our new body and I'm still having back focus issues. Not as much as before but the camera is totally unreliable. Is anyone else having these issues?? Seems weird I am having the same issue twice with 2 different bodies. My lens (24-70) was checked out as well and had no reportable issues.