Canon EOS 5D Mark III Instruction Manual page 84

Lenses and Usable AF Points
Group G
Autofocusing with only 33 points is possible. (Not possible with all 61
AF points.) All of the AF area selection modes are selectable. During
automatic AF point selection, the outer frame marking the AF area
(Area AF frame) will be different from 61-point automatic selection AF.
EF 180mm f/3.5L Macro USM
Group H
Only the AF point at the center of the viewfinder, and the surrounding
AF points (above, below, on the right and on the left) can be used for
autofocusing. Only the following AF area selection modes are
selectable: Single-point AF (Manual selection), Single-point Spot AF
(Manual selection), and AF point expansion (Manual selection
EF 35-105mm f/4.5-5.6
84
: Cross-type AF point. Subject
tracking is superior and high-
precision focusing is achieved.
: AF points sensitive to horizontal lines.
: Disabled AF points (not displayed).
EF 180mm f/3.5L Macro USM
+ Extender EF 1.4x
: Cross-type AF point. Subject
tracking is superior and high-
precision focusing is achieved.
: AF points sensitive to horizontal lines
(on the right and on the left of the
center AF point) or vertical lines
(above and under the center AF
point). Manual selection is not
possible. Only available when "AF
point expansion (Manual selection
)" is selected.
: Disabled AF points (not displayed).
EF 35-105mm f/4.5-5.6 USM
EF 1200mm f/5.6L USM
).