Specifications

EF lenses fuse state-of-the-art
electronics with mechanical precision,
and optical excellence. The fully
electronic EF lens mount is unique
among 35mm SLR cameras, operating
silently with unmatched reliability
due to the complete elimination of
mechanical couplings. Every EF
lens contains its own custom-designed
autofocus motor and microprocessor.
Many utilize Canon’s exclusive
Ultrasonic Motor (USM) technology.
Canon is also a leader in the use of aspherical lens elements, flourite crystal, Ultra-low dispersion (UD) glass and other
advanced optical technologies. Uniformly high optical performance results from the extensive use of exclusive Canon-developed
manufacturing techniques in Canon’s own factories, the world’s largest for 35mm cameras and lenses.
CANON
EF LENSES
CAMERAS & LENSES
32
For Any Inquiries Regarding Your Order, Call Our Customer Service:
[phone] • [phone] • FAX: [phone] • [phone]
PHOTO - VIDEO - PRO AUDIO
Inner and Rear Focusing
An inner focusing lens has the focusing lens group(s) in front of the diaphragm, while a
rear focusing lens has the focusing lens group(s) behind. Both systems allow the focusing
lens group to be small. This minimizes the load on the actuator which drives the
autofocus. In turn, the AF speed is faster. The whole optical system can also be made
more compact. And, since the lens doesn’t rotate during focusing, the effects of a circular
polarizer or gel filter remain intact.
Floating System
Ordinary lenses (non-zoom) are designed to give the best results when the correction of
aberrations is most effective. This is usually at the most commonly-used focusing
distances. At other focusing distances especially at the closest focusing distance,
aberrations tend to appear. Canon’s floating system suppresses aberrations at close
focusing distances. The system adjusts the gap between certain lens elements in
correspondence to the focusing distance, effectivel
y correcting the aberration. The result is
high image quality with aberrations suppressed at all focusing distances.
Built-In Motor and EMD
EF lenses have a built-in AF motor for driving energy with lower transmission loss. The
lenses also have an EMD (Electromagnetic Diaphrag
m) to electronically control the aper-
ture with unmatched precision. The aperture can be set either with an electronic dial or
with the electronic pulse signal sent according to the exposure reading.
Full-Time Manual Focusing
EF lenses have very high AF precision, quickly achieving optimum focus in almost any
shooting situation. Most are also equipped with Canon’s full-time manual focusing mode
to make picture-taking even more flexible. Lenses with this feature let you switch to man-
ual while in AF mode—overriding the autofocus mode. You can keep looking through the
viewfinder and touch up the focus manually without switching the focus mode switch.
Two type of manual focusing: Electronic manual where the rotation amount of
the focus-
ing ring is detected and the focusing motor is driven electronically. Or, mechanical
focus-
ing, where the rotation of the focusing ring adjusts the focus mechanically.
Fully Electronic Mount System
In designing the EF lens mount, Canon engineers
gave a lot more than just a way to quickly attach a
lens to a camera body. The fully electronic mount
system has none of the shock, operational noise,
abrasion, slow response or design restrictions
related to linkage mechanisms used to transfer
data. Instead, about 50 items of information are
exchanged as digital signals between the lens and
camera in real time. This enables high-speed and
precision control as well as improved reliability.
◆ Quiet, high-speed, high-precision AF from
fisheye to super telephoto since the optimum
actuator can be incorporated into each lens.
◆ Quiet, high-precision aperture, or digital
diaphragm control.
◆ Allows the aperture to be stopped down to pre-
view depth of field and helps increase shooting
speed by keeping the aperture stopped down
during continuous shooting sequences.
◆ Permits fully automatic diaphragm control with
Canon tilt-shift TS-E lenses.
◆ Using variable-aperture zoom lenses, any manu-
ally set f/stop (except for maximum aperture) is
maintained throughout the zoom range.
◆ Automatic compensation and display of the
change in the lens’ effective F-number when an
extender is mounted between lens and camera.
◆ Self-test system using the lens’ built-in micro-
computer warns of malfunctions through the
camera’s LCD to help ensure high reliability.