Solution
[One-Shot AF] for Still Subjects[AI Servo AF] for Moving Subjects
[AI Focus AF] for Automatic Switching of AF Mode
Selecting the AF Mode
This camera has three types of AF modes that can be selected to accommodate different shooting conditions and subjects.
In the ⋖ ⋗(Scene Intelligent Auto) mode, [AI Focus AF] is set automatically.
[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 which achieved focus will flash briefly in red, and the focus confirmation light [ ] in the viewfinder will also 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. For further information, please refer to the Related information section "Shooting with Focus Lock (EOS 5D Mark III)".
Caution
[AI Servo AF] for Moving Subjects
This AF mode is for moving subjects when the focusing distance keeps changing. While you hold down the shutter button halfway, the subject will be focused continuously.
Caution
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.
[AI Focus AF] for Automatic Switching of AF Mode
[AI Focus AF] switches the AF mode from [One-Shot AF] to [AI Servo AF] automatically if the still subject starts moving.
After the subject is focused in the [One-Shot AF] mode, if the subject starts moving, the camera will detect the movement and change the AF mode automatically to AI Servo AF.
Caution
When focus is achieved in the [AI Focus AF] mode with the Servo mode active, the beeper will sound softly. However, the focus confirmation light [ ] in the viewfinder will not light. Note that focus will not be locked in this case.
Selecting the AF Mode
1. Set the lens focus mode switch to ⋖AF⋗.
2. Press the ⋖AF・DRIVE⋗ button.
3. While looking at the LCD panel, turn the ⋖Main Dial⋗ to select the AF mode.