So remember how previously I stated that the autofocus points on the Canon 1D Mk IV do not track the subject in your frame? I was wrong. After shooting a soccer game on the Lower East Side the other day, I’ve come to the conclusion that the Canon 1D Mk IV will only track subjects with a USM lens of some sort. Obviously, the camera needs to be switched into AI Servo mode and the focusing points need to be selected. More on the performance after the jump.