AF Modes: Differences between One-Shot AF, AI Servo AF, and AI Focus AF (EOS REBEL T4i/EOS 650D)
17-May-2012
8201521000
Solution
This camera has three types of AF modes that can be selected to accommodate different shooting conditions and subjects. In the Basic Zone modes, the optimum AF mode 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 dot inside the AF point achieving focus lights 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 "Shooting with Focus Lock".
NOTE
- If focus cannot be achieved, the focus confirmation light [●] 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)".
- In the [
] menu, If the [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 point selection is automatic, the camera first uses the center AF point to focus. During autofocusing, if the subject moves away from the center AF point, focus tracking continues as long as the subject is covered by another AF point.
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.
[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.
1. Set the lens focus mode switch to <AF>.
2. Press the <AF> button.
3. [AF mode] will appear. Press the <Cross keys> to select the AF mode, then press <SET>.
- ONE SHOT: One-Shot AF
- AI FOCUS: AI Focus AF
- AI SERVO: AI Servo AF