Nikon D780 DSLR Camera (Body Only) - Manual (Page 204)

158 Shooting Settings
❚❚
Subject Tracking AF
If [ Auto-area AF ] is selected for AF-area
mode during live view, you can press J
to enable focus tracking. The focus point
will change to a targeting reticle;
position the reticle over the target and
press the
AF-ON button or press J again
to start tracking. The focus point will track the selected subject
as it moves through the frame (in the case of portrait subjects,
focus will track the subject’s face). To end tracking, press
J a
third time. To exit subject-tracking mode, press the W ( Y )
button.
D Subject Tracking
The camera may be unable to track subjects if they move quickly, leave
the frame or are obscured by other objects, change visibly in size, color, or
brightness, or are too small, too large, too bright, too dark, or similar in
color or brightness to the background.