Nikon D4S - Manual (Page 340)

318
U
Choose the function assigned to the B
button for vertical shooting.
a9: Assign AF-ON Button (Vert.)
G button
➜ A Custom Settings menu
Option Description
G
Same as AF-ON
button Both B buttons perform the function selected
for Custom Setting a8.
A AF-ON
Pressing the vertical B button initiates
autofocus.
B AE/AF lock
Focus and exposure lock while the vertical B
button is pressed.
C AE lock only
Exposure locks while the vertical B button is
pressed.
D
AE lock (Reset on
release)
Exposure locks when the vertical B button is
pressed, and remains locked until the button is
pressed a second time, the shutter is released, or
the standby timer expires.
E AE lock (Hold)
Exposure locks when the vertical B button is
pressed, and remains locked until the button is
pressed a second time or the standby timer
expires.
F AF lock only
Focus locks while the vertical B button is
pressed.
None
No operation is performed when the vertical B
button is pressed.