Canon EOS 5D Instruction Manual page 20

Nomenclature
Mode Dial
Camera User Settings
Most camera settings can be registered under w,
x, or y (p.206).
20
F : Bulb (p.99)
a : Manual exposure (p.94)
f : Aperture-priority AE (p.92)
s : Shutter-priority AE (p.90)
d : Program AE (p.88)
Fully-Automatic Modes
All you do is press the shutter button.
Fully-automatic shooting suitable for the
subject.
1: Full Auto (p.48)
C: Creative Auto (p.51)