Nikon SB-5000 Reference Manual page 112

Camera's LCD
D
D-32
Determine the guide number
according to the flash output
level and the zoom head
position.
• For more information, see
"Specifications" (0H-25).
Calculate the aperture f-number
from the flash-to-subject
distance and the guide number,
and set the camera's aperture
accordingly.
• To determine the f-number,
see "Guide Number, Aperture
and Flash-to-subject Distance"
(0H-6).
• Aperture cannot be set on the
SB-5000.