Specifications

46
usa.canon.com/eos
47
EF LENSES
in high-end super-telephoto L-series lenses.
Composed of crystallized calcium fluoride
(CaF2), a single Fluorite element, although
costly, has roughly the corrective power of
two UD-glass elements, giving these L-series
lenses their spectacular performance and
relatively compact design.
Aspherical Elements
Wide-angle lenses and fast normal-focal-
length lenses often suffer from spherical
aberration. When the light rays coming
through the center of the lens do not converge
at the same point as light rays coming through
the lens edge, the image appears blurred
because there is no sharp point of focus.
Canon’s Aspherical elements use a varying
curved surface to ensure that the entire image
plane appears focused. Aspherical optics
also help to correct curvilinear distortion as
one might find in ultra wide-angle lenses.
Canon designs aspherical elements with
extremely precise variable curvature of one
or both sides, making possible lighter, more
compact lenses.
Subwavelength and Fluorine
Anti-smear Coatings
The Subwavelength Coating (SWC) is a
proprietary lens coating that helps control
ghosting and flare to a far greater degree than
with earlier coating technologies. Utilizing SWC
technology on large-curvature lens elements
that are mainly found in wide-angle lenses
significantly minimizes the occurrence of
ghosting and flare caused by reflected light in
environments that have posed problems. SWC
is used on the Canon wide-angle lens, EF 24mm
f/1.4L II USM. The Fluorine anti-smear coating
keeps soiling, smears and fingerprints to a
minimum for easy cleaning.
Focus Preset
Focus Preset enables you to program a focusing
distance in the camera’s memory. Normal
picture taking and focusing are unaffected
by preset distances. For example, at a soccer
game, you Focus Preset the goal area. Shoot
normally elsewhere on the field, but once the
action moves toward the goal, the user can
instantly return to the preset distance by turning
a ring on the lens.
Ultrasonic
Motor
Canon developed the
world’s first lens-based
Ultrasonic Motor (USM)
to power the lens
autofocus mechanism.
Instead of large noisy
drive trains powered by
conventional motors,
Canon USM lenses
employ the minute electronic vibrations
created by piezoelectric ceramic elements.
The focusing action of the lens is fast and quiet,
with virtually instantaneous stops and starts.
USM lenses also draw minimal power from
the camera, ensuring longer battery life. Canon
makes two types of Ultrasonic Motor lenses.
Ring-type USM lenses, found in large aperture
and super-telephoto designs, permit manual
focusing wit hout first switching out of the auto
mode. Micro USM designs bring the performance
benefits of Canon’s USM technology to a wide
assortment of affordable EF lenses.
L-Series Lenses
Most highly regarded among professional
photographers, Canon L-series lenses are
distinguished by a bold red ring around the
outer barrel. What make s them truly dis tincti ve,
however, is their remarkable optical
performance — the result of sophisticated
Canon technologies, such as Ultra-low
Dispersion UD glass, Fluorite and Aspherical
elements and Super Spectra Coating.
Fluorite / UD Elements
Reducing color fringing, or chromatic aberration,
has been one of the great challenges in the
design of telephoto lenses. L-series telephoto
lenses – like the EF 70–200mm f/2.8 IS II USM
and EF 300mm f/4L IS USM – employ Canon’s
Ultra-low Dispersion glass to minimize this effect,
providing much improved contrast and
sharpness. Even more effective at suppressing
chromatic aberration are Fluorite elements, used
STM
A challenge of shooting DSLR video has been
achieving continuous autofocus. In response,
certain new Canon EF, EF-S and EF-M lenses now
offer a stepping motor (STM) drive, designed to
deliver smooth and quiet continuous AF during
video shooting when paired with the Movie
Servo AF feature found on select EOS cameras.
Canon’s decades of proven optical expertise
allows Canon to incorporate the right type of
stepping motor for each lens. The EF 40mm
f/2.8 STM utilizes a gear-type that allows the
lens to achieve an ultra-compact and light-
weight design; whereas the EF-S 18–135mm
f/3.5–5.6 IS STM uses a lead-screw type,
which prioritizes AF performance, offering the
smoothest and quietest operation.
Diffractive Optics
Canon’s use of diffractive optics (DO) results
in high-performance lenses that are much
smaller and lighter than traditional designs.
Canon’s unique multilayer diffractive elements
are constructed by bonding diffractive coatings
to the surfaces of two or more lens elements.
These elements are then combined to form a
single multilayer DO element. Conventional
glass lens elements disperse incoming light,
causing chromatic aberration. The DO element’s
dispersion characteristics are designed to
cancel chromatic aberrations at various
wavelengths when combined with conven-
tional glass optics. This technology results in
smaller lenses with no compromise in image
quality. Canon has also developed a new
triple-layer type DO lens that uses an advanced
diffractive grating to deliver excellent
performance, with superb control of color
fringing. This configuration is ideal for
zoom lens optics and provides significant
reductions in size. A good example is the EF
70–300mm f/4.5–5.6 DO IS USM lens, which
is 28 percent shorter than the EF 70–300mm
f/4–5.6 IS USM lens.
Ring-type USM
Micro USM
Convergence of parallel light
rays by an Aspherical lens.
Spherical aberration
of spherical lens.
Optical Image Stabilizer Mode 2
and Mode 3
The standard settings of the Optical Image
Stabilizer are set so that it is most effective
when photographing stationary subjects.
However, when panning with a moving subject is
attempted (tracking of the subject horizontally
or vertically), the shake-correction of the OIS
may inadvertently over-compensate and
interfere with framing. To help resolve this,
Canon developed Optical Image Stabilizer
Mode 2. In this mode, if you move the lens to
follow a subject for a pre-determined time, the
Optical Image Stabilizer does not correct for the
intentional panning, while continuing to correct
any camera shake that’s perpendicular to the
panning motion. The result is a virtually smooth
viewfinder image as you follow the moving
subject. Optical Image Stabilizer Mode 3
activates IS only when the shutter button is
fully pressed, allowing for easy panning of
fast-moving subjects.
Hybrid Image Stabilizer
During normal shooting
situations, sudden camera
movement is rotational and can cause
significant image blur. During macro or close-up
photography, however, the image blur caused
by linear camera shake – when the camera
moves parallel to the subject – is more
pronounced. Optical Image Stabilizer is
optimized to counteract rotational or linear
camera shake and works well for most camera
shooting situations. To help compensate for
linear camera shake, a new acceleration sensor
determines the amount of shift-based camera
movement. Canon Hybrid Image Stabilizer
technology employs a highly sophisticated
algorithm that combines the feedback of both
the acceleration sensor and angular velocity
sensor (found in Hybrid OIS technology), and
moves the image stabilizer lens elements,
effectively compensating for both rotational
and linear camera shake. Hybrid IS dramatically
enhances the effects of Optical Image
Stabilizer, especially during macro shooting,
which may be difficult for conventional image
stabilization technologies.
Dynamic Image Stabilizer
During video shooting, Canon’s Dynamic IS
stabilization offers a greater image
stabilization correction range, creating an
Image Stabilizer effect equivalent to a shutter
speed approximately 4 settings faster,
effective for shooting handheld, while walking,
and in similar types of shooting situations.
Linear Camera Shake
Glass
Red
Blue
Red
Blue
Fluorite
Anomalous
dispersion
Comparison of optical characteristics between
optical glass and Fluorite
Taken with EF 100–400mm f/4.5–5.6L IS USM
Chromatic aberration canceled out
Chromatic aberrations reversed from
that of a refractive optical element
Image formation in the red, green
and
blue wavelength order
Red Green Blue
Multi-Layer Diffractive Optical Element
Refractive Optical Element
and Multi-Layer Diffractive
Optical Element Combined
Refractive Optical Element
Image formation in the blue, green
and red wavelength order
Chromatic aberrations
Correction of Chromatic Abberation by the Multi-Layer
Diffractive Optical Element