Nikon Autofocus Speedlight SB-24 - Manual (Page 93)

EXPOSURE COMPENSATION IN NON-TTL AUTO
FLASH MODE
The Non-TTL Auto Flash mode works best for subjects of
average (18% gray) reflectance. For very dark subjects, we
recommend closing the aperture about 1/2 to 1 stop smaller
than indicated on the SB-24 LCD. For very bright (almost white)
subjects, it is just the opposite. Open the aperture about 1/2 to
1 stop. Similarly, the automatic system operates best under
average indoor conditions in the home—an average-size room
having white ceilings approx. 2.5 to 3 meter (8 to 10 feet) high.
In a very large room, or in one with very high ceilings, such as
an auditorium, if you are more than about 4.5 to 6 meters (15 to
20 feet) from the subject, you should experiment by opening the
aperture 1 to 2 stops wider than the LCD indicates. Since there
is no way to anticipate any specific condition, you may want to
take a few pictures using exposure bracketing.