I just got my new body and candidly I'm upgrading from a much lesser camera. Can someone explain in simple terms the different AF selection modes and when to use them. I'm having trouble focusing using all 61 points on the intended subject and getting the right focus point and I thought I would use this mode as a default. Can I focus the center point on the subject in this mode and press the shutter half way and then change the composition and have the focus point remain on the subject? Also, if I want to shoot my son playing soccer with a wide open aperture what is the best focus mode? Am I Better off with something like point expansion mode and then will the square continue to track my son. Any general tips would be great. Thanks