Unfortunately, even the best settings won't work all the time. If you set your focusing system the way I recommend, there is (at least) one situation that will turn out badly: when your subject is moving quickly toward or away from your camera. When your camera focuses, it focuses at a certain distance. If the distance between your camera and your subject changes between the time you focus and the time you take the picture, your subject will be out of focus.
Let me explain this with an example. In the picture above, my daughter was swinging and so the distance between her and the camera was constantly changing. With my normal settings I was getting pictures out of focus because as I would push the button, the focus would lock when it got half way down and then the image would be captured when the button was depressed all the way. She was swinging quickly enough that there was enough time between focusing and capturing the image for the distance to change.
So here is the solution:
When your subject is moving toward or away from your camera (more quickly than walking), set your "Focus Mode" to "Continuous-servo AF" (AF-C). To do this push the "MENU" button on the back, navigate to the "Custom Settings Menu" (the pencil), then select "02 Focus mode," and highlight "Continuous-servo AF." In this mode, your camera will continue focusing right up until you take the picture no matter how long you hold the button half-way down.
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