To enable autofocus on many professional and semi-professional cameras use a special switch that can be installed in two modes: AF or M. AF: a standard abbreviation for the function name of sensor M includes a manual sharpening. If the camera this switch is absent, then the mode selection is carried out via the corresponding menu item. If you can't find this function, use the manual for the camera, which usually comes in the kit.
On some cameras, the autofocus also has various modes. AF-A is responsible for fully automatic adjustment of field of a picture. The camera automatically determines the object on which to focus. This function is appropriate for most frames.
Mode AF-S allows you to shoot static scenes, such as landscapes or portraits. AF-C includes a mode in which the camera is focused on a moving subject until, until you press the shutter button. This function is well suited for shooting fast moving objects in the frame.
Some cameras have the function of setting the AF area, which can be adjusted manually. In most cases, is suitable focus on the nearest object. This option in the settings is the icon of the white rectangle. The dynamic area allows you to make a more accurate adjustment for focus for moving subjects in the frame, and the operating point (Single Point) can be used to adjust the focus on a specific area in the frame. This feature is useful when you know what exactly should be in focus – for example, the human eye in a portrait.
For most personnel can recommend the use of automatic mode AF-A, because in most cases it does its job and does not require the photographer works specific. If any of the specific points of focus did not suit you, only then should adjust any parameters.