A little background. I have been using a 6D for the last several years and pretty much keep the camera set to use the center spot for focusing. I do not have knowledge or experience using a sophisticated focusing system. My interests lie in landscape, nature, and other slow moving subjects, BUT... I have 3 sons and football is a big part of our family. I am the photographer for all football games that our local high school plays. I have been shooting with my 6D and have done pretty well overall. Yesterday, I fortuitously became the owner of a 5D Mark IV, but now I need help understanding the complex (at least to me) focusing system. I have read the manual and still do not understand when and why to use the different choices. I have searched the internet to find sites and/or videos to explain and have come up empty handed. My first question: How different is the Mark 4 system from the Mark 3? Will learning about the Mark 3 correlate with the Mark 4? Do you know of a source to learn this system? Or can you guide me to the best way to set up the focusing for nighttime high school football games?

Last night, after having the camera 3 hours, I used the new camera to shoot a football game using only the center focus point. Blew the 6D away, but I know I want to use the full capability of the new camera. I would appreciate any help I can get!

TIA!