18
AI Servo AF
AF expansion with selected point 2
C.Fn III-8
Important C.Fn
Reliably focus-track subjects with extreme left
and right movement
AF point expansion expanded by 1 point on left and right is effective for horizontal movement
When increasing the number of AF points with area expansion to
capture fast moving subjects, option 2: ‘Assist AF point expanded by
surrounding points’ is the most versatile and easy to use setting.
However, with extremely fast subjects that are limited to left and right
movement, shooting with option 1: ‘Expanding left and right AF
point,’ and using only the AF points on the left and right of the
selected AF point with area expansion is recommended. You will want
to use this setting with subjects having mainly horizontal movement,
however, when held vertically it will be up/down Assist AF points, so
option 1 is the best setting when shooting events and scenes with
mainly up and down movement.
1 point selected
2 point selected
Manually selected AF point
AF point area expansion
(Red SI displays when SW-1 is
on.)
When using C.Fn III-8 AF Expansion with option 3: ‘Use all 45 points’ selected, during AI
Servo AF, (if the center AF point is manually selected), 6 AF points in the rows above and
below, and 3 AF points to the right and left (total 18 focus points) are available. The AF
Expansion area follows the subject wherever it moves within the 45-point AF coverage area.
All 45 AF points operate in this instance.
