Nikon N4004s - Manual (Page 27)

PROGRAM AUTO EXPOSURE MODE
Program auto is the easiest exposure mode to use, since it
controls both aperture and shutter operation. The microcomputer
in the N4004S automatically sets the best combination of
shutter speed and lens aperture, and matches these with the
correct dual program (normal or high speed) for the lens in
use. Normal program is selected for lenses with focal lengths
shorter than 135mm. High-speed program is selected for lenses
with longer focal lengths to reduce the possibility of blurred
pictures due to subject movement or camera shake. With zoom
lenses, either normal or high-speed program will be selected,
depending on the focal length setting.
The EV (Exposure Value) chart demonstrates the difference
between normal and high-speed programs of the N4004s.
Follow either colored line to where it intersects a diagonal line.
This shows the combination of aperture (vertical line) and
shutter speed (horizontal line). For example, at a brightness of
EV10, the N4004S selects f/2.8 and 1/125 sec. with AF 180mm
f/2.8 lens at ISO 100, or f/4 and 1/60 sec. with an AF 50 mm
f/1.4 lens at ISO 100.