I photographed a fireworks display last night with my D5 and things didn't go well. I set up on a tripod, full wide angle, manual focus set at infinity. I would touch nothing but the shutter release button, sometimes letting the camera "go to sleep" between shots, sometimes taking them quickly enough the D5 stayed powered up. Time after time, I would have to check the viewfinder because the focus had shifted to points like .2 meters. Not always the same new focus point, always way off -- I'm confused. Surely this can't be related to the AF problems of the D5.