Canon EOS 6D Mark II Mode D'emploi page 116

AF Area Selection Mode
Large Zone AF (Manual selection of zone)
The AF area is divided into three focusing zones (left, center, and right)
for focusing. Since the focusing area is larger than with Zone AF and all
the AF points in the selected zone are used for Automatic selection AF,
it is superior to Single-point AF in tracking the subject, 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>.
Automatic selection AF
The Area AF frame (entire AF area) is used to focus. The AF point(s)
achieving focus is displayed as <S>.
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With One-Shot AF, pressing the shutter button
halfway will display the AF point(s) <S> that
achieved focus. If multiple AF points are
displayed, it means they all have achieved focus.
This mode tends to focus on the nearest subject.
With AI Servo AF, you can set the AI Servo AF's
initial position with [8C.Fn II-11: Initial AF pt,
AI Servo AF] set to [1: Initial
selected] or [2: Manual S AF pt]. As long as the
Area AF frame can track the subject during
shooting, focusing will continue.
AF pt