Nikon F4 Instruction Manual page 55

1. Set lens to minimum aperture setting (largest I-number),
With
AF
Nikkor lenses, lock lens aperture ring at minimum
setting,
3. Lightly press shutter release button and confirm exposure,
2. Rotate shutter speed dial to select desired shutter speed
within the range lrom 4 to 1/8000 sec, in 1 EV steps,
Slower speeds down to 30 sec, are only available in PH, P or
A mode,
Aperture is controlled steplessly within the aperture range of the lens and indicated
in 1/2 EV steps,
55