The Canon Digital Learning Center posted a short yet comprehensive article about how to set and switch rapidly between AF points and functions. The EOS 5D Mark III is used as example, but the principles apply to every Canon DSLR.
Canon’s engineers have included a plethora of tools in recent EOS cameras to aid the photographer in getting that perfect focus. They have included great features such as more autofocus points, smaller Spot type focus points, three options for expanding the size of an AF point, and even a joystick to control them. While each AF Area setting has its place in different shooting situations, what if you want to use two interchangeably from shot to shot without slowing down?