Canon EOD 50D Instruction Manual page 271

• Camera shake _
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~--'~ ~
\J~:'~~
Image Stabilizer Parallel Movement Principle
Camera shake
\_~-~-\i
Capturing
element
I
~
---j
IS lens group
1. Lens When still
2. Camera shaken
...
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-
How do Canon IS Lenses repress blurring
caused by camera shake?
Canon IS lenses detect camera shake with a pair
of built-in gyro sensors, shifting lens components in
the direction of the vibration to counteract it and
prevent blurring. When the shutter button is pressed
halfway while the IS function is on, compensation
for camera shake is activated in just
0.5
seconds.
Since the potential optical performance of the lens
is optimized, you can capture beautiful images.
Image Stabilizer Unit
How effective is the shake compensation
capability of Canon IS Lenses?
0 " - - - - - - - - - - - - - - - - - -
• To avoid camera shake. the general rule is to use a shutter speed
that is the reciprocal of the focal length (1/focallength x 1.6).
• There will be a 90% or higher chance of the shot not being blurred by camera shake.
1/125
(sec)
1/60
1/30
• Image Stabilizer can be used within 0.5 sec.
after you press the shutler button halfway.
Image Stabilizer ON
1/15
---- ,,--
, ,
, ,
, ' ' Approx. 3 stops _
"
" "
"
Image Stabilizer ,,"
OFF"
"
.....
'"
..........
1/8
50
(%)
100
EF-S17-85mm 1/4-5.6 IS USM Image Stabilizer
Effect Graph (1
=
85mm)
Generally, the shutter speed that allows photographers to shoot photos without blurring is "1 Ifocallength". Of course,
the faster the shutter speed, the greater the benefit in blur reduction. In comparison with lenses that lack an image
stabilizer, Canon IS Lenses can achieve the same
blur-free clarity at shutter speeds that are 2 to 5 stops
(increments) slower. Let's take a look at an EF-S 17-
85mm
f/
4-5.6 IS USM lens, for example. Since the
maximum focal length of this lens is effectively
136mm with cameras* like the EOS DIGITAL REBEL
XSi/450D and others that feature APS-C image
sensors, the slowest shutter speed that could
normally be used while maintaining a blur-free
image is
1/125
sec. However, when the IS function
is activated, the shutter speed can be reduced 3
stops to
1/15
sec. without blurring. Thus, you can
shoot subjects at slower shutter speeds without fear
of
blurred images - dramatically expanding your
range of shooting situations and photo variations.
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