Canon EOS 70D Operation Manual - Page 101

f: Selecting the AF OperationN One-Shot AF for Still Subjects Suited for still subjects. When you press the shutter button halfway, the camera will focus only once. When focus is achieved, the AF point that achieved focus will be displayed, and the focus confirmation light in the viewfinder will also light up. AF point Focus confirmation light With evaluative metering, the exposure setting will be set at the same time focus is achieved. While you hold down the shutter button halfway, the focus will be locked. You can then recompose the shot if desired. If focus cannot be achieved, the focus confirmation light in the viewfinder will blink. If this occurs, the picture cannot be taken even if the shutter button is pressed completely. Recompose the shot and try to focus again, or see "When Autofocus Fails" (p.109). If [z1: Beep] is set to [Disable], the beeper will not sound when focus is achieved. After achieving focus with One-Shot AF, you can lock the focus on a subject and recompose the shot. This is called "focus lock". This is convenient when you want to focus on a subject not covered by the Area AF frame. AI Servo AF for Moving Subjects This AF operation is suited for moving subjects when the focusing distance keeps changing. While you hold down the shutter button halfway, the subject will be focused continuously. The exposure is set at the moment the picture is taken. When the AF area selection mode is set to 19-point automatic selection AF (p.103), the camera first uses the manually-selected AF point to focus. During autofocusing, if the subject moves away from the manually-selected AF point, focus tracking continues as long as the subject is covered by the Area AF frame. With AI Servo AF, the beeper will not sound even when focus is achieved. Also, the focus confirmation light in the viewfinder will not light up. 101