Choosing Live View Focusing Pairs with a Nikon D7000
The way the Nikon D7000 sets focus during Live View and movie shooting depends on the setting of the Focus-mode selector (AF for autofocus or M for manual focus) and, for autofocusing, your Autofocus mode and AF-area mode. If you use the kit lens (or a similar lens), you also need to set the switch on the lens barrel to either A for autofocusing or M for manual focusing.
Until you get fully acquainted with all the various focusing options and can make your own decisions about which pairings you like best, keep things simple (okay, sort of simple) by breaking things down like this:
For moving subjects: Set the Autofocus mode to AF-F and the AF-area mode to Wide Area. You also can try the Subject Tracking AF-area mode. Either way, remember that in AF-F mode, you don't press the shutter button halfway until you're ready to lock focus and take the picture — focusing begins immediately after you switch the Autofocus mode to AF-F and continues until you press the shutter button halfway.
For movie recording, keep your finger off the shutter button if you want the camera to continuously adjust focus during the recording. And again, note that if you use the camera's internal microphone, the sound of the autofocus motor may be audible in the movie. (One solution is to use an external microphone placed away from the camera.)
For stationary subjects: Set the Autofocus mode to AF-S and the AF-area mode to Wide Area. Or, if you're shooting a portrait, give the Face Priority AF-area option a try. Note that in a group shot, the camera usually locks on the closest face. Press the shutter button halfway to initiate focusing; after the camera finds the focusing point, focus is locked. For movie recording, you can then release the shutter button. For still photography, keep your finger on the button — otherwise, focus will be reset at the time you press the button to take the picture.
For difficult-to-focus subjects: If the camera has trouble finding the right focusing point when you use autofocus, don't spend too much time fiddling with the different autofocus settings. Just set the camera to manual focusing and twist the focusing ring to set focus yourself.