Canon EOS-1D X Mark II DSLR Camera (Body Only) - Manual (Page 97)

97
AF Area Selection Modes
The manually-selected AF point < S > and surrounding AF points < w >
are used to focus. Focusing is performed over a wider area than with
AF point expansion (manual selection
). Effective when it is difficult to
track a moving subject with just one AF point.
AI Servo AF and One-Shot AF work in the same way as with AF point
expansion (manual selection
) mode (p.96).
The AF area is divided into nine focusing zones for focusing. All the AF
points in the selected zone are used for the automatic AF point
selection. It is superior to single-point AF or AF point expansion in
achieving focus, and it is effective for moving subjects.
However, since it is inclined to focus on the nearest subject, focusing on
a specific target may be more difficult.
The AF point(s) achieving focus is displayed as <
S >.
AF point expansion (Manual selection, surrounding points)
Zone AF (Manual selection of zone)