Canon EF - Manual (Page 75)

M
Changing Lenses
One of the nice features of an SLR is its lens
interchangeability. An SLR is not really a SINGLE
LENS reflex at all, because it can use many lenses of
various focal lengths. In the design of an SLR, the
type of lens mount and its construction are very
important factors. The EF camera uses the Canon
Breech-Lock IVIount first developed in 1959. This
unique mount combines the virtures of sturdiness,
rugged dependability and fast operation. The mount
holds the lens securely in place with absolutely no
wobble or play and insures that the lens is always
exactly the same distance from the film plane.
Changing lenses is a rapid procedure requiring a little
more than one-eight of a turn of the breech-lock ring
on the back of the lens. To remove the lens from the
camera, turn the breech-lock ring counterclockwise
until it stops and pull the lens away from the camera
body. Mounting another lens on the camera body Is
a simply procedure. Just align the red dot on the
breech-lock ring of the lens with the red dot located
under the name "Canon" engraved on the front of
the camera's pentaprism. Push the back of the lens
into the camera body and turn the breech-lock ring
clockwise until it Is tight.