5D MKIII focus question
I take photos at marathons occasionally and can not figure out how to get the camera to focus in the center point all the time. I have read the manual and watched youtube videos and there are just too many options. Is there a simple setting to make the camera do this? The focus will jump from a runner to a branch or other person that is closer. I use a 100 -400 push pull Canon lens. Thank you for any help.