Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 916)

Group H
The 23 AF points shown here are available for autofocusing. As the AF area selection mode,
choose from Spot AF, 1-point AF, Expand AF area:
, Zone AF (manual selection), or 23-
point Automatic selection AF.
With an extender attached to extendable lenses, AF is available when maximum aperture is
f/8 (in a range of f/5.6–f/8).
: Cross-type AF point. Offers excellent subject tracking and high-precision focusing.
: AF points sensitive to horizontal lines (AF points left and right of the center) or vertical
lines (AF points above and below the center).
: Disabled AF points (not displayed).
Caution
Expand AF area: applies to the 23 available AF points. Expansion for manually
selected AF points that are not surrounded by active AF points is limited to any
available adjacent points.
If the maximum aperture value is slower than f/5.6 (greater than f/5.6 but not
exceeding f/8), focus may not be achieved with AF when shooting low-contrast or
low-light subjects.
If the maximum aperture value is slower than f/8 (greater than f/8), AF is not
possible during viewfinder shooting.
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