Canon EOS 70D Operation Manual - Page 102

f: Selecting the AF OperationN AI Focus AF for Switching the AF Operation Automatically AI Focus AF switches the AF operation from One-Shot AF to AI Servo AF automatically if a still subject starts moving. After the subject is focused in One-Shot AF, if the subject starts moving, the camera will detect the movement, change the AF operation automatically to AI Servo AF, and keep tracking the moving subject. When focus is achieved with AI Focus AF with the Servo operation active, the beeper will continue beeping softly. However, the focus confirmation light in the viewfinder will not light up. Note that focus will not be locked in this case. AF-Assist Beam with the Built-in Flash Under low-light conditions, when you press the shutter button halfway, the built-in flash may fire a brief burst of flashes. It illuminates the subject to enable easier autofocusing. AF-assist beam will not be emitted by the built-in flash in , , or mode, or when [Flash firing] is set to in , , , , or mode. The AF-assist beam cannot be emitted with AI Servo AF operation. The effective range of the AF-assist beam emitted by the built-in flash is approx. 4 meters/13.1 feet. In Creative Zone modes, when you raise the built-in flash with the button, the AF-assist beam will fire when necessary. 102