Nikon F4 Instruction Manual page 18

With Battery Pack MB-20
To switch camera on: while pressing
lock release, turn film advance mode
selector from
L
(lock) position to
S, CH,
Cl, Cs
or
~ .
@
Next, lightly press the shutter release button and confirm viewfinder LCD appears.
LCD stays on for approx. 16 sec. after you take your finger off button. This indicates
sufficient battery power.
- - m '
.
"
If it turns off immediately after you remove your finger from the button, replace batteries.
18