Canon EOS Rebel T5i 18-55mm IS STM Lens Kit - Manual (Page 102)

102
S Selecting the AF PointN
With maximum apertures up to f/5.6:
Cross-type focusing (vertical and horizontal lines detected
simultaneously) is possible with all AF points. With certain lenses (see
below), the off-center AF points will detect only vertical or horizontal
lines (no cross-type focusing).
With maximum apertures up to f/2.8:
High-precision AF* with vertical and horizontal lines detection is
possible with the center AF point, in addition to the cross-type focusing
(vertical and horizontal lines detected simultaneously).
The remaining eight AF points enable cross-type focusing in the same
way as when using lenses with maximum apertures up to f/5.6.
* Except with the EF28-80mm f/2.8-4L USM and EF50mm f/2.5 Compact Macro.
The following lenses enable only horizontal-line sensitive focusing with
the three AF points on the left and the three AF points on the right and
only vertical-line sensitive focusing with the top and bottom AF points.
Cross-type focusing is possible only with the center AF point.
EF35-80mm f/4-5.6
EF35-80mm f/4-5.6 II
EF35-80mm f/4-5.6 III
EF35-80mm f/4-5.6 USM
EF35-105mm f/4.5-5.6
EF35-105mm f/4.5-5.6 USM
EF80-200mm f/4.5-5.6 II
EF80-200mm f/4.5-5.6 USM
AF Operation and Maximum Lens Apertures
Lenses not Enabling Cross-Type Focusing with all AF Points
If you use an Extender (sold separately) and the maximum aperture
becomes smaller than f/5.6, AF shooting will not be possible (except in
[u+Tracking], [FlexiZone - Multi], and [FlexiZone - Single] during Live
View shooting). For details, refer to the Extender’s instruction manual.
COP
Y