Reference Guide

12
Advanced EOS·1 Technology ~
The EF Lenses
Canon's system of sophisticated autofocus lenses are
widely recognized
as setting the standards for superior
optical performance. The large-aperture L series
EF lenses
provide an
even wider choice of professional-use autofocus
lenses.
EF 50mm f/1.0L
EF 85mm f/1.2L
EF 20-35mm f/2.8L
Large-aperture lenses are often essential for serious
photography. With the EF
SOmm fll.OL, Canon has
created a lens with brightness capabilities surpassing those
of the human eye. The EF 8Smm fl1.2L is also an excep-
tionally. fast short telephoto lens that serves as
an excellent
portrait lens. The
EF 20-3Smm f 12.SL is a super wide-angle
zoom lens which remains bright during zooming.
• Aspherical Elements
These new L series lenses use aspherical elements
manufactured with Canon's high-level polishing technology
in order to achieve an image quality
that is virtually free of
the spherical aberrations that can cause diminished sharp-
ness in large aperture lenses.
• Floating Element construction
The optical system employs a floating element
construction to compensate for curvature
of field during
focusing and ensure high image quality at all shooting
distances. Good color balance
is attained through the use of
a new, exclusively-developed multi-layer coating for the
high-refractive index glass. Designed for full-aperture
photography, Canon's
new L Series lenses offer superlative
image quality, brightness and blur effect, plus great wide-
angle coverage with the
EF 20-3Smm fl2.SL.
EF 80-200mm f/2.8L
The large aperture EF SO-200mm fl2.SL features an
outstanding zoom range for high image quality and superior
operability to meet the needs
of professionals. During
zooming the aperture does not change, making it ideal for
a variety
of applications - from outdoor photos to studio
shots that require flexibility.
• Three UD Glasses
The optical system consists of three elements of UD
glass that maintain high image quality and compensate for
the chromatic aberrations which often occur with large-
aperture telephoto lenses.
Ultrasonic Motor
Some L series lenses employ an ultrasonic motor to
handle
AF operation within the lens. USM incorporates
a ring-shaped motor
that maintains the traditional lens
shape. As it
is a direct-drive system with no gearing units,
operation
is astonishingly fast, reliable and virtually silent.
Greater compactness and operational simplicity are realized
by using low rotational speed and high torque, thereby
eliminating the need for a braking unit.
And the speed and
noiseless operation has to be experienced to be fully
appreciated.
The electronic focusing rings on USM lenses work
together with the
AF mechanism to provide superior
operability. The focusing motor
is driven according to the
electrically-detected rotation
of the focusing ring. It's
a system
of power-assisted focus, since as the ring is turned,
pulse signals are generated by an encoder
that instructs the
microprocessor in the lens to drive the USM accordingly.
With the
EF 200mm f / 1.SL, the EF 300mm f 12.SL, and the
EF 600mm fl4L, there's a 3-step variable focusing rate,
making it possible
Ultrasonic Motor (USM)
to focus rapidly for
quick-moving sub-
jects
or to select
high-precision
focusing control
as the situation
warrants .
Focus Preset
Selected large-aperture telephoto lenses - the EF
200mm fl1.8L, the EF 300mm fl2.SL, and the EF 600mm
fl4L - have a focus preset function that can "lock in"
a focus setting. The photographer can focus
on other shots,
then when necessary return immediately to the preset focus
at the touch
of a button.
Focus Preset Operation
Lru
( PRESET)
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( FOCUS SET)
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(1) AF ranging posHlon set as "0"
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Position set as "0"
(2) Normal AF photography
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Position changed 10 steps
(3) Focus restored to preset position
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Position moved back 10 steps