The d2x camera, from Nikon, has an excellent autofocus option
that can be used to capture fast action. It has been designed in
such a way that it can lock on to a target, keeping it in focus no
matter what happens. This is great for taking pictures of one
person on a basketball court, for example. It can be very hard to
find this focus on your own because you need to have such a fast
reaction time. You should use the autofocus function if things are
happening quickly and could take you by surprise so that the shot
is clear.