In these pictures where the subjects are moving. It is a lifesaver! For this one, I just focus on the chest area where there is the most contrast.
And this one with kids running all over, again I can stay in sharp focus!
Here is how to set your camera
1. Go to custom function 4 and set it to setting 1. (setting 0 is default)
2. Turn your AF setting to AI Servo.
After you get your camera set. You use the * button that is on the top right corner of your camera
I love it! Give it a try and see how it works for you:)