The Inside Track - Nikon D3body - D3 Body 12mp FX Digital SLR Camera Technical Manual

Example 3
Choose longer lock-on times when photographing a runner
on the inside track or in other situations in which your subject
may be blocked for relatively long periods.
AF-C priority selection:
Release

The Inside Track

Dynamic AF area:
9 points or 21 points
Focusing with Autofocus
Your subject
Focus tracking with
lock-on: Long
13