Canon EOS-1D X Mark III EOS-1DX Mark III Advanced User Guide - Page 348

AF point display After automatic face detection by the camera (single frame) After manual face selection (double frame) Note Selecting a face manually by tapping the screen or using < > locks onto that subject for tracking, and the camera tracks the subject even if it moves within the screen. To release locked tracking, tap [ ]. Caution Tapping the screen to focus will focus with [One-Shot AF], regardless of the AF operation setting. If the subject's face is significantly out of focus, face detection will not be possible. Adjust the focus manually ( ) so that the face can be detected, then perform AF. An object other than a human face may be detected as a face. Face detection will not work if the face is very small or large in the picture, too bright or too dark, or partially hidden. AF may not detect subjects or people's faces at the edges of the screen. Recompose the shot to center the subject or bring the subject closer to the center. The camera will keep moving the active AF point to track subjects when Servo AF is set, but under some shooting conditions (such as when subjects are small), it may not be possible to track the subject. 348