Understand auto focus modes - One-Shot AF, AI Servo AF, and AI Focus AF - EOS 7D Mark II

Article ID: ART168633 | Date published: 10/13/2017 | Date last updated: 11/24/2017


Learn about the different auto focus modes for your EOS 7D Mark II camera: One-Shot AF, AI Servo AF, and AI Focus AF. Includes instructions and guidance about why you would choose one over another. 


You can select the auto focus operation characteristics to suit the shooting conditions or subject. In the < > mode, "AI Focus AF" is set automatically.

Video - Auto Focus Guide - Getting Started

Selecting the auto focus mode

  1. Set the lens focus mode switch to <AF>.
    AF - MF switch
  2. Switch <ON> the camera.
    Camera power switch
  3. Set the Mode Dial to one of the < P / Tv / Av / M / B > modes.
    Mode Dial
  4. Press the <DRIVEAF> button.
    DRIVEAF button
  5. While looking through the viewfinder, or at the LCD panel, turn the <> dial to select the auto focus mode. Auto focus is possible in the <P>, <Tv>, <Av>, <M>, or <B> modes by pressing the <AF-ON> button.
    • ONE SHOT: One-Shot AF
    • AI FOCUS: AI Focus AF
    • AI SERVO: AI Servo AF
      Adjustment dial
      AI FOCUS highlighted on the LCD

[One-Shot AF] for still subjects

Suited for still subjects. When you press the shutter button halfway, the camera will focus only once.
ONE SHOT highlighted in the LCD
  • When focus is achieved, the AF point flashes briefly in red and the focus confirmation light <>in the viewfinder lights.
  • 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.
  • If focus cannot be achieved, the focus indicator <> in the viewfinder blinks. 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 Difficult subjects for AF (Auto Focus) (EOS 7D Mark II).
  • If [  Beep] is set to [Disable], the beeper does not sound when focus is achieved.
  • After achieving focus with One-Shot AF, you can lock the focus on a subject and recompose the shot. This is called Shooting with Focus Lock (EOS 7D Mark II). This is convenient when you want to focus on a peripheral subject not covered by the Area AF frame.

[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.
AI SERVO highlighted in the LCD
  • The exposure is set at the moment the picture is taken.
  • When the AF area selection mode is set to 65-point automatic selection AF, focus tracking will continue as long as the Area AF frame covers the subject.
With AI Servo AF, the beeper does not sound even when focus is achieved. Also, the focus indicator < > in the viewfinder does not light up.

[AI Focus AF] for Automatic Switching of AF Mode
AI FOCUS highlighted in the LCD

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 One-Shot AF, if the subject starts moving, the camera detects the movement and changes the AF operation to AI Servo AF. The camera also starts tracking the moving subject. When focus is achieved with AI Focus AF with the Servo operation active, the camera beeps softly. However, the focus indicator <> in the viewfinder does not light up. Focus is not locked in this case.

Good to know

For more information about auto focus, refer to Difficult subjects for AF (Auto Focus) (EOS 7D Mark II).

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