Canon EOS Rebel T2i Brochure page 15

EF LENS TECHNOLOGY
Great images start with great lenses and, in many ways, an SLR is defined by the quality,
breadth and scope of its associated system of lenses. For many, Canon EF series lenses
alone are reason enough to choose the EOS System. A blend of some of the world's most
advanced optical, microelectronic, and precision manufac-
turing technologies, EF lenses are perfected in Canon's
laboratories and proven in the field. Whatever you
shoot, whatever your budget, there are Canon
EF lenses perfect for your needs.
Optical Image Stabilizer
Canon Optical Image Stabilizer technology makes
handheld photography more practical at slow
shutter speeds, accommodating more low-light
shooting situations than ever before. Camera
shake typically occurs at shutter speeds less
than 1/ [focal length], resulting in image blur.
Canon Optical Image Stabilizer technology uses
miniature sensors and a high-speed microcom-
puter built into the lens. The sensors analyze
vibrations and apply correction via a special
stabilizing lens group that shifts the image
parallel to the focal plane. Motion blur is
©Arthur Morris
Image Stabilizer OFF Image Stabilizer ON
canceled, resulting in a sharper image. With Optical
Image Stabilization, it's like gaining up to four stops.
Canon Optical Image Stabilizer technology is built
into many EF or EF-S lenses and outperforms in-
camera stabilization technologies found in other
cameras by allowing for more movement of the
stabilizing lens group. Especially with telephoto
lenses, as the lens focal length increases, the effect
of shake and the degree of correction needed to
cancel it increase as well. With the Optical Image
Stabilizer in the lens, Canon can equip each IS lens
with a stabilization unit optimized for the focal
lengths and optical characteristics unique to that
lens Other systems are limited by how far they can
move an image sensor, and as a result their stabi-
lization is less effective as telephoto lengths get
longer. Also, the result of Optical Image
Stabilization can be seen right in the viewfinder—
impossible with some other stabilizer systems.
Image Stabilization: It Belongs In the Lens
Because every lens is different, different lenses
have different Optical Image Stabilizer needs.
• Reduces motion blur by counteracting camera shake during handheld photography
• With Optical Image Stabilizer in the lens, Canon can equip each Optical Image Stabilizer lens with the
stabilizer it needs
• Found on some telephoto lenses, Optical Image Stabilizer Mode 2 is especially effective when doing
panned shots
• With Canon Optical Image Stabilizer, the effects of the stabilization can be seen in the viewfinder—the
image is steadier, making composition more accurate
How the Image Stabilizer Works — The Optical Image
Stabilizer shifts a lens group in parallel to the focal plane.
When the lens jerks due to camera shake, the light rays
from the subject are bent relative to the optical axis, result-
ing in a blurred image. Camera shake is detected by two
gyro sensors (one each for the yaw and pitch). The gyro
sensors detect the angle and speed of the camera shake
caused by handheld shooting. By moving select lens
elements according to how the entire lens is being shaken,
the image passing through the lens can be steady and
sharp when it hits the imaging sensor. The figure on the
right shows what happens when the lens is jerked down-
ward. The center of the image moves downward on the image shake occurs in both the horizontal and vertical
focal plane. When the Optical Image Stabilizer lens group
directions, the Optical Image Stabilizer lens group can shift
shifts downward, the light rays are refracted so that the vertically and horizontally on a plane perpendicular to the
image center returns to the center of the focal plane. Since optical axis to counteract the image shake.
Optical Image Stabilizer in effect, right in the viewfinder.
Close-up — For close-up shots, Low-light — In low light situa-
even the tiniest of motions is tions, when you would normally
magnified and spoils a great expect to have to use flash or
shot! tripod, Canon's Optical Image
Stabilizer lenses give you the
freedom of up to 4 stops of light.
EF LENSES
Optical Image Stabilizer Parallel
Movement Principle
1: No Camera Shake
Camera
Shake
2: Lens Front Shake Downward
Optical Image Stabilizer Units
3: Image-stabilizing group counteracting
downward camera shake
Telephoto — Canon designs
each Optical Image Stabilizer
system to complement the
lens' focal length. So even
with telephoto lenses you'll
capture the shot!
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