When shooting a static subject always shoot on (Nikon) single servo and (Canon) One shot mode. This is to prevent the lens hunting and looking to change auto focus, but rather locking focus at the half press of the shutter.
When photographing a moving subject change your af drive to (Nikon) Continuous and (Canon) Ai Servo.
|Single servo AF (AF-S)
Camera focus when shutter release button is half pressed and locks when the in-focus indicator (a solid dot) appears on the viewfinder status LCD. If the subject is moving when the shutter release button is half pressed the camera will focus track until a lock can be obtained. In this mode the default is for focus priority, this means that a shot can only be taken with a good focus lock, you can also choose release priority via CSM a2.
|Continuous servo AF (AF-C)
The camera will focus continuously while the shutter release button is half pressed, if the subject moves the camera will adjust focus to compensate. In this mode the default is for release priority, this means that a shot will be taken whether or not the camera has a good focus lock, you can also choose focus priority via CSM a1.
Focusing is achieved manually by turning the lens manual focus ring. Focus indicator on the viewfinder status LCD will still indicate whether or not the selected manual focus is the same as the calculated auto focus. This mode is always release priority.
|Auto focus mode
• One Shot (focus lock on half-press)
• AI Focus (locks but monitors movement)
• AI Servo (continuous predictive focus)
AI Focus mode initially locks just like One Shot mode but monitors the focused subject, if the subject moves it will automatically switch to an AI Servo operation.
• Single shot
• Self-Timer 10 sec (IR mode)
• Self-Timer 2 sec (IR mode)
You can optionally combine self-timer with mirror lockup (to reduce mirror induced vibration) via C.Fn III-6.