Canon EOS 5D Mark III Instruction Manual (en)

 Selecting AI Servo AF Characteristics (For a Subject)N
Once an AF point starts tracking the 
subject, this setting enables the camera 
to focus consecutive subjects at different 
distances. If a new subject appears in 
front of the target subject, the camera will 
start focusing the new subject. Also 
effective when you want to always focus 
on the closest subject.
Geared for tracking moving subjects 
whose speed can change dramatically 
and suddenly.
Effective for subjects having sudden 
movements, sudden acceleration/
deceleration, or sudden stops.
Case 3: Instantly focus on subjects suddenly entering AF points
Default settings
• Tracking sensitivity: 
[Responsive: +1]
• Accel./decel. tracking: [+1]
• AF pt auto switching: [0]
Case 4: For subjects that accelerate or decelerate quickly
If you want to quickly focus a subject appearing suddenly, setting [Tracking 
] to [+2] may give better results (p.92).
Default settings
• Tracking sensitivity: [0]
• Accel./decel. tracking: [+1]
• AF pt auto switching: [0]
If the moving subject suddenly and greatly changes speed, setting [Accel./
decel. tracking
] to [+2] may give better results (p.93).