Autofocus Mode and Priority

Choosing the right autofocus mode (AF-S, AF-C, or Manual) is another key to focusing success. To save battery power, your D5100 doesn’t start to focus the lens until you partially depress the shutter release or press the AE-L/AF-L button on the back of the camera. But, autofocus isn’t some mindless beast out there snapping your pictures in and out of focus with no feedback from you after you press that button. There are several settings you can modify that return at least a modicum of control to you. Your first decision should be whether you set the D5100 to AF-S, AF-C, or Manual.

You can set any of the three modes using the information edit screen, as described previously. Navigate to the focus mode area of the screen, and select one of the three modes described next.