A2: Af-S Priority Selection; A3: Focus Tracking With Lock-On - Nikon D5 User Manual

a2: AF-S Priority Selection

When AF-S is selected for viewfinder photography (0 101), 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
changes in the distance to the subject when
AF-C is selected during viewfinder
photography (0 101).
❚❚ Blocked Shot AF Response
Choose how quickly focus responds when something passes
between the subject and the camera. Choose from values
between 5 (Delayed) and 1 (Quick). The higher the value, the
slower the response and the less likely you are to lose focus on your
original subject. The lower the value, the quicker the response and
the easier it is to shift focus to objects crossing your field of view.
Note that 2 and 1 (Quick) are equivalent to 3 when 3D-tracking or
auto-area AF is selected for AF-area mode (0 104).
U
326
Photos can be taken whenever the shutter-release
button is pressed.
Photos can only be taken when the in-focus indicator
(I) is displayed.
G button ➜ A Custom Settings menu
Description
G button ➜ A Custom Settings menu
) is
I