Nikon D100 Manual page 78

Focus
To select the AF-area mode, set the function dial to [+] and rotate the main
command dial. The current AF-area mode is indicated by the focus-area dis-
play in the control panel:
Single-area AF Dynamic-area AF
Predictive Focus Tracking
If the camera autofocus system detects that the subject is moving when the shutter-
release button is pressed halfway, it will automatically initiate predictive focus tracking.
If the subject is moving toward or away from the camera, the camera will track focus
while attempting to predict where the subject will be when the shutter is released. In
single-servo autofocus, the camera will initiate predictive focus tracking if the subject
was moving when the shutter-release button was pressed halfway. Focus will lock
when the subject stops moving. In continuous-servo AF, the camera will also initiate
predictive focus tracking if the subject starts moving after the shutter-release button is
pressed halfway. Focus will not lock when the subject stops moving.
If AF-ON is selected for Custom Setting 14 (AE-L/AF-L), predictive focus tracking will
also take effect when the AE-L/AF-L button is pressed.
Predictive focus tracking is not available in manual focus mode.
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