A2: Af-S Priority Selection; A3: Focus Tracking With Lock-On - Nikon D4s User Manual

a2: AF-S Priority Selection

When AF-S is selected for viewfinder photography (0 97), this
option controls whether photographs can be taken only when the
camera is in focus (focus priority) or whenever the shutter-release
button is pressed (release priority).
Option
G Release
F Focus
Regardless of the option selected, if the in-focus indicator (
displayed when AF-S is selected for autofocus mode, focus will lock
while the shutter-release button is pressed halfway. Focus lock
continues until the shutter is released.

a3: Focus Tracking with Lock-On

This option controls how autofocus adjusts to sudden large
changes in the distance to the subject when AF-C is selected during
viewfinder photography (0 97).
Option
C 5 (Long)
( 4
D 3 (Normal)
) 2
E 1 (Short)
Off
U
314
Photos can be taken whenever the shutter-release
button is pressed.
Photos can only be taken when the in-focus indicator
(I) is displayed.
When the distance to the subject changes abruptly, the
camera waits for the specified period before adjusting
the distance to the subject. This prevents the camera
from refocusing when the subject is briefly obscured by
objects passing through the frame.
The camera immediately adjusts focus when the
distance to the subject changes. Use when
photographing a series of subjects at varying distances
in quick succession.
G button ➜ A Custom Settings menu
Description
G button ➜ A Custom Settings menu
Description
) is
I