AF Operation: Differences between One-Shot AF, AI Servo AF, and AI Focus AF (EOS 70D)
27-Jun-2013
8201829200
Solution
This camera has three types of AF operation that can be selected to accommodate different shooting conditions and subjects.
NOTE
- In the Basic Zone modes, the optimum AF operation is set automatically for the respective shooting mode.
Icons used on this page:
[ 
]: Shooting tab 1 / <
>: Main Dial / <
>: Quick Control Dial
]: Shooting tab 1 / <>: Main Dial / <>: Quick Control DialSuited 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 up briefly in red, and the focus confirmation light [●] in the viewfinder will also light up.
- 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.
NOTE
- 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 "Subjects Difficult to Focus" in the Related information.
- If [ : Beep] is set to [Disable], the beeper will not sound when focus is achieved.
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, 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 up.
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.
NOTE
When focus is achieved in the AI Focus AF operation with the Servo mode active, the beeper will sound softly. However, the focus confirmation light [●] in the viewfinder will not light up. Note that focus will not be locked in this case.
1. On the lens, set the focus mode switch to <AF>.
2. Turn the Mode Dial to a Creative Zone mode.
3. Press the <AF> button.
4. While looking at the LCD panel, turn the <> or <> dial.
> or <> dial.
- ONE SHOT: One-Shot AF
- AI FOCUS: AI Focus AF
- AI SERVO: AI Servo AF