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| DO
(Diffractive Optics) technology |
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| Canon
introduces the first multilayered Diffractive
Optic lens of the world, with the EF
400mm f/4 DO lens. The prototype will
be in commerce this year. |
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The
optical element equipping it has the characteristics
either of the fluorite
lenses, and of the aspherical
ones, thus representing a revolutionary
evolution in photo optics.
The
multilayered diffractive lenses are constructed
with the goal to alter the light path inside
the lenses and to not scatter part of that
light as happens with normal lenses: here,
in fact, all the light is forced to describe
the image. Moreover, this kind of lenses
correct the chromatic aberration (the different
colors focus at different distances) even
better than the expensive fluorite lenses,
while, calibrating the spacing of the diffractive
group also the spherical aberration is corrected,
rendering useless the resource of the expensive
aspherical lenses. |
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construction of these new lenses requires
a micrometric precision and three-dimensional
instrumentations patented by the same Canon. |
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| IS
(Image Stabilizer) System |
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| One
of the causes of a photography failure is
always has been the "moved", so
the only alternative to a tripod was the
use of more sensible films or the resource
to a fortune support. Canon therefore has
developed an image stabilizing system, using
it either in the telecameras and inserting
it into the lenses.
The
vibrations transmitted from the hand to
the camera transmit also to the lens and
therefore to the optical elements. The lens
movement causes the movement of the image
formed, regarding the optical axis. If,
therefore, the elements could move independently
from the system, the problem would be resolved.
This idea has been the assumption to the
development of Canon's stabilizing system.
The system is based on the connection of
two vibrating gyroscopes that detect the
vertical and horizontal vibrations and command
an equal and contrary reaction of the sophisticated
optical group assigned to the correction.
The answer time of the correction is in
the order of 1/2,000 of a second. It turns
out a corrective effect equal to two stops
in terms of exposure: the gain is therefore
of two stop (equivalents to a 2 stop more
luminous lens or to a 2 stop faster film)
before a really moved image.
The
stabilization system is useful also in the
panning technique (you follow a moving
subject moving your camera). The software
detects the movement typical of the technique
and switches off the correction in the direction
of the panning, keeping on only the correction
of the vibration in the other directions.
IS
Mode 2: this new technology automatically
determines that the movement is conscious
panning and halts correction in the relevant
direction, thereby preventing shake-return.
The IS Mode 2 system automatically detects
lack of movement / vibration to prevent
operation errors when a tripod is in use.
IS efficacy increases and lower overall
size have been achieved through improvements
in the moving contact sections of the IS
lens barrel, the IS lens group barrel locking
mechanism and the shake-detection gyro. |
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In
the 1987 Canon adopted for the first time
the ultrasonic motor (USM) for the autofocus
lenses. The main characteristics were the
high speed and the low noise, conquering
the favour of all the sport- and nature-
photographers of the world. Thanks to the
innovation without comparisons, the manual
lenses were abandoned very soon.
In
the 1992 Canon developed an USM micromotor
that could be produced industrially: currently,
those USM micromotors equip nearly all the
lenses of the Canon panorama.
The
operation of the USM motor is based on the
transmission of a vibration produced by
an ultrasonic wave. Therefore, the motor
ring doesn't require neither gears, nor
any electromagnetic field sources and supplies
a very fast, noiseless answer with a very
low energetic consumption. The range of
use of the system goes from -30°C to
+60°C. |
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| EMD
(Electromagnetic Diaphragm) |
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EMD
(Electromagnetic Diaphragm) is a diaphragm
drive control actuator, which is a component
integrating both a stepping motor and a
diaphragm blade unit in a single unit, used
for fully-electronic data transmission EF
mount system. Every EF lens incorporates
an EMD unit as a basic component of the
EOS system. EMD controls diaphragm blade
by a stepping motor and aperture diameter
by electronic pulse signal from the camera
body to overcome the problem of conventional
mechanical diaphragm units, while also provides
benefits that conventional mechanism does
not offer. |
High-precision
digital diaphragm control is much more accurate
than with conventional mechanical linkage
systems. Extremely quiet operation because
of no shock of mechanical levers. Compactness
thanks to the integrated diaphragm control
components. |
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Canon
has developed the control of the autofocus
automatism through the movement of the pupil.
The mechanism is set in action by the semipression
of the push-button, but in this case the
AF activates on the AF cell nearest the
exact point where the photographer is watching
through the view-finder.
The
control through the pupil happens thanks
to an infrared lighting system of the pupil
and to the detection of the rays reflected
from the cornea and to the monitoring of
the relative positions of the eye and the
same pupil: this allows a sensor to calculate
the bending angle of the eye and to activate
the sensor in the calculated direction. |
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advanced algorithm controls the variables
that would cause an error: direct light
on the eye, presence of glasses, tears,
etc. The algorithm requires a very short
initial calibration, to record the physical
aspects of the eye of the photographer (or
of other photographers). |
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Canon
continues in its search to obtain an automatic
focusing function covering virtually any
point of the shot. In the beginning there
was the single focusing point, then they
was three, then five. With the birth of
the EOS-3 the points have reached the number
of 45, scattered in an area of 8x15 mm.
The 45 points are either vertical and horizontal
and they are active also in very animated
shots. This system has been installed also
in the new EOS1-V, after significant testing
sessions made by many professionals. The
45 points are supported by a CMOS sensor
with an efficiency from 30 to 40 times better
than the ordinary AF sensors. |
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When
warm air comes in contact of a cold glass,
then the humidity of the air condenses on
the glass. In these conditions, lenses and
view-finders can cloud and you need to wait
for long time before the condenses evaporates.
The
problem is strong for winter photographers:
they must lend the highest attention not
to breath on the sensitive glasses of their
equipment, in order to avoid to lose important
time. |
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Anti-Fogging technology developed by Canon
concurs to absorb condenses into a thin
synthetic film deposited on the external
surface of the glass. The film is composed
of two polymers, one organic and one inorganic.
The first one absorbs condenses, while the
second prevents the disaggregation of the
first and its separation from the glass.
The film is also abrasion-resistant. |
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A
photographic spherical element has a fundamental
defect: it cannot make converge in a single
fire point the parallel rays entering the
element, so the optical image is not a clear
image. Some standard optical groups correct
the aberration, but they are not right if
you want to reduce the dimensions or the
weight of the system. These limits are exceeded
using the aspherical optical elements, but
they are difficult to construct, demanding
a working accuracy equal to 0.1µm
or less.
In order to industrially produce the aspherical
elements, Canon developed a line for the
dedicated construction, thanks also to the
use of control instruments with a precision
of 0.02µm (laser interferometer) and
to machines for the aspherical working never
constructed before. Canon has then perfected
the system, differentiating the workings
on the base of photographic requirements.
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The
subdivision of the light in different colors
(wavelengths) causes the chromatic aberration
during light passaging through a conventional
element: the different colors are focused
at different distances, causing a chromatic
under-focusing. In order to correct it,
it's a necessity an optical group constituted
by a convex and a concave lenses: it works
good, but it doesn't correct the green spectrum.
For this reason, Canon has constructed the
fluorite lenses, in order to focus all the
colors in the same point nearly to the perfection.
Fluorite (CaF2) is a mineral with particular
features, as the low refraction index and
a low dispersion, but in nature is not diffused
and large enough to drawn industrial lenses.
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For this reason, Canon developed in 1969
a process of synthetic crystallization of
the fluorite and produced the first lens
equipped of a fluorite element. Currently,
nearly all the telephoto lenses and the
professional zooms mount a fluorite element.
A
particular care is required in the working
phases (grinding and polishing), that need
sophisticated technologies: microscopical
diamond abrasion in order to achieve a polishing
with a ruvidity under the 0.002µm. |
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