AF Modes: Differences between One-Shot AF, AI Servo AF, and AI Focus AF (EOS 5D MArk III)
28-Feb-2012
8201498000
Solution
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.
>(Scene Intelligent Auto) mode, [AI Focus AF] is set automatically.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)".
NOTE
- If focus cannot be achieved, the focus confirmation light [
] and AF status indicator [ 
] in the viewfinder will blink. If this occurs, a picture cannot be taken even if the shutter button is pressed completely. Recompose the picture and try to focus again. Or refer to the Related information "Difficult subjects for AF (Auto Focus)". - If [
: Beep] is set to [Disable], the beeper will not sound when focus is achieved.
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.
- The exposure is set at the moment the picture is taken.
- When the AF area selection mode is set to 61-point automatic selection, 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.
NOTE
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.
] in the viewfinder will not light.[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.
NOTE
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.
] in the viewfinder will not light. Note that focus will not be locked in this case.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.
