Nikon D700 - Manual (Page 312)

286
U
A 3D-tracking
When the shutter-release button is pressed halfway, the colors in the area
surrounding the focus point are stored in the camera. Consequently 3D-
tracking may not produce the desired results with subjects that are the
same color as the background or that occupy a very small area of the
frame.
f 51 points
(3D-tracking)
If the subject leaves the selected focus point, the
camera will use 3D-tracking to track the subject
and select a new focus point as required. Use to
quickly compose pictures with subjects that are
moving erratically from side to side (e.g., tennis
players). If the subject leaves the viewfinder,
remove your finger from the shutter-release button
and recompose the photograph with the subject in
the selected focus point.
Option Description