Canon EF 35-80mm f/4-5.6 III Lenses Manual - Page 11

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Canon EF 35-80mm f/4-5.6 III Lenses Manual

Technology where it counts

Canon's innovations put your images on film quickly, quietly, and easily with outstanding results.

Canon started to develop

manufacturing technology for

Aspherical elements early on.

Ultrasonic Motors (USM)

We eventually succeeded in

establishing a mass-production

The Ultrasonic Motor (USM) in

grinding and polishing process with

Canon EF lenses is the world's

a polishing precision of 5/10,000 mm.

first lens-based motor. Based on

In 1971, Canon marketed the

a totally new technology, the motor

FD 55mm f/1.2AL lens, the world's

spins by ultrasonic oscillation energy.

first large-aperture Aspherical lens

The USM is quiet and quick. It has

for SLRs. This was followed by many

made EF lenses almost noiseless

other Canon lenses incorporating

and autofocusing fast, precise,

Aspherical elements and they were

and practical. The direct-drive

well-received.

construction is very simple, with no

gear train. This makes it durable and

Also, Canon developed

efficient. It also consumes little power.

mass-production technology for

Two types of USM are used:

glass-moulded aspherical elements

Ring-type USM and Micro USM.

and replicated Aspherical lenses.

The former type is found in

The former was produced by an

large-aperture and super telephoto

ultra-high-precision aspherical

lenses, while the latter is used in

lens-moulding machine which

more compact lenses. Using the

shaped the glass directly. For the

optimum type of USM in the

latter, the Aspherical surface was

lens results in maximum efficiency

formed by ultraviolet-hardened resin

and effectiveness.

film applied on a spherical element.

Canon has developed numerous

compact-size lenses, taking full

advantage of Aspherical elements

to attain high image quality.

MRing-type USM

Spherical aberration of spherical lens.

Convergence of parallel light rays by

Micro USM

an Aspherical lens.

Aspherical Lenses

Diffractive Optics

Ordinary spherical elements have

In another world's first in camera

an inherent flaw in that the

lens optical design, Canon introduced

point of focus for the lens centre

new technology in order to build a

does not match that of the lens

super telephoto that complements its

periphery. Spherical aberrations of

latest compact film and digital SLR

large-aperture lenses and distortion

cameras. This cutting-edge technology

by ultra-wide-angle lenses cannot

employs diffractive optical elements

be resolved with spherical elements

that use the principle of diffraction

alone. The Aspherical lens element

to change the direction of the

was therefore developed.

lightwave's path. This revolutionary

The curvature of the lens element is

element has Aspherical

calculated and shaped to achieve the

characteristics, which help define

ideal single point of focus. The result

superior maximum aperture image

is high contrast with minimal flare

quality, as well as optical qualities

even with a large-aperture lens.

superior to UD-glass to totally

Distortion can also be effectively

correct colour fringing.

corrected in ultra-wide-angle lenses.

The Multi-Layer Diffractive Optical

Elements exhibit outstanding ability

Since longer wavelengths form an

to correct chromatic aberrations

image closer to the lens due to the

(colour defects), and are especially

large diffractive angle, and shorter

effective in super telephoto lens

wavelengths form an image farther

design where these specific types

from the lens due to the smaller

of optical defects are most likely to

diffractive angle, putting the DO

happen. You can see how well the

elements with conventional glass

technology works in your own

optics actually cancels out each

pictures by examining the straight

other's chromatic aberrations and is

edges of a subject in your picture.

exceptionally effective in correcting

You will see a crisp, clear edge

this optical defect. The diffraction that

without the telltale, prismatic colour

occurs with Canon's Multi-Layer

fringing that is visible with images

Diffractive optical elements actually

shot using inferior optics.

corrects the optical system's

chromatic aberrations and improves

Diffractive

the image formation performance.

grating

The net result of Canon's

DO technology is a lens design

with reduced size and weight while

Glass

offering higher image quality than a

lenses

Cross-section

Front view

comparable focal length lens that

Multi-Layer Diffractive Optical Element Construction

incorporates conventional glass

optical elements. It means a new

generation of high-performance

Refractive Optical Element

lenses that complement the more

Chromatic aberrations

Refractive Optical

compact designs of our latest

Element and Multi-

Layer Diffractive

SLR film and digital cameras.

Optical Element

Image formation in

Combined

the blue, green, and

red wavelength order

400mm f/4 Lens Designed with a Refractive

Multi-Layer Diffractive

Optical Element Only

Optical Element

Chromatic aberrations

reversed from that of a

Chromatic aberration

refractive optical element

canceled out

Image formation in the red, green,

and blue wavelength order

Red

Green

Blue

Correction of Chromatic Aberration by the

317mm

UD element

Multi-Layer Diffractive Optical Element

Fluorite

400mm f/4 DO IS USM

(Incorporates Multi-Layer Diffractive Optical Element)

Glass lens elements refract, or bend,

lightwaves as they pass through to

form an image. That's simply the

naturally occurring physics of light.

We use multiple elements and

special glass to help keep the waves

232.7mm

focused like a pinpoint instead of

Multi-layer diffractive optical element

(Including removable

Fluorite

spreading them into the rainbow of

colour seen when light passes

Lens Downsizing with the Multi-Layer Diffractive

through a glass prism. To diffract a

Optical Element

lightwave means that the ray goes

Note: If a very bright spotlight like a mercury lamp

is photographed with a DO lens, a ring of light

through a change in direction before

may occasionally appear around the light source,

passing through the lens. The change

due to the imaging characteristics of the Multi-

in direction is caused by a diffraction

Layer Diffractive Optical Element.

grating – very fine parallel grooves

or slits on the surface. Canon found

that using a concentric diffraction

grating that gets smaller toward the

edges – some as fine as tenths of a

micrometre – solved of one many

inherent physical limitations of

camera optics. The design also

makes it possible to obtain the

same effect as an Aspherical lens.

And taking the technology a step

beyond, we actually use two

single-layer diffractive optical

elements whose diffraction gratings

are bonded together face-to-face.

Image Stabilizer

No matter how great the lens is,

camera shake can spoil the shot.

Blurred photos due to camera shake

usually occur when the shutter

speed is slower than the reciprocal

of the lens focal length.

For example, a shutter speed slower

than 1/200 sec. at the 200mm focal

length can invite a blurred photo

caused by camera shake. In such

cases, a tripod is necessary.

However, a tripod can be a heavy

and troublesome burden when you

go hiking or travelling. There are

even places where using tripods is

prohibited. Using a slow shutter

speed then becomes difficult.

To resolve this problem, Canon

became the first manufacturer to

Floating System

incorporate an Image Stabilizer in an

SLR camera lens. Optical shake is

Ordinary lenses are designed to

detected by gyro sensors which

give the best results when the

provide the data necessary to shift

correction of aberrations is most

the image-stabilizing lens group in

effective. This is usually at the most

parallel to neutralise the shake.

commonly used focusing distances.

This increases the usable shutter

At other focusing distances,

speed range by up to two full steps

especially at the closest focusing

for hand-held shooting. Except for

distance, aberrations tend to appear.

the EF 28-135mm f/3.5-5.6 IS USM

Canon's floating system suppresses

and EF 75-300mm f/4-5.6 IS USM

aberrations at close focusing

lenses, IS lenses have two IS modes.

distances. This system adjusts the

One is for normal image stabilisation

gap between certain lens elements

and the other is for panned shots.

in correspondence to the focusing

With a monopod, the Image

distance. The aberration is effectively

Stabilizer on all IS lenses operates

corrected. The result is high image

normally as during hand-held

quality with aberrations suppressed

shooting. Also, the EF 300mm f/2.8L

at all focusing distances.

IS USM, EF 400mm f/2.8L IS USM,

Weight: 3,000g

EF 500mm f/4L IS USM, and EF

TS-E 24mm f/3.5L Floating System

600mm f/4L IS USM lenses have a

mechanism that prevents having the

Closest

shooting

Image Stabilizer turned on while the

distance

lens is mounted on a tripod.

1: No camera shake

Group 1 (focusing group)

Weight: 2,080g

Group 2 (image-stabilizing group)

Film

tripod collar)

plane

Floating Effect (TS-E 24mm f/3.5L)

Object

Group 3 to 6

2: Lens front shakes downward

3: Image-stabilizing group counteracting

downward camera shake

Astigmatism

Floating System

Direction of Group 2

movement

How the Image Stabilizer Works in the

EF 75-300mm f/4-5.6 IS USM

Circular Aperture

Certain Canon lenses feature a new

Circular Aperture diaphragm unit,

which uses curved aperture blades

to provide for a more rounded

With Image

opening as the lens is stopped down.

Stabilizer on

It's especially effective at rendering

out-of-focus background highlights

as natural rounded shapes. In lenses

such as the EF 70-200mm f/2.8L IS

lens, the lens opening is virtually

circular from f/2.8 to f/5.6.

These lenses retain all the benefits

previously available with Canon's

Electromagnetic Diaphragm

With Image

Stabilizer off

—smooth and consistent stop-down

operation (even at up to 10 fps

with the EOS-1v), near-silent aperture

control, and total absence of

mechanical levers or switches in

the lens mount.

Full-Time

Manual

Input pulse board for

Focusing

electronic manual focusing

Canon EF lenses and EOS cameras

have very high AF precision.

Optimum focus can be achieved

quickly for almost any shooting

situation. Recent EOS cameras have

been equipped with multiple

focusing points for higher flexibility

in composing a photo while using

AF. Picture-taking is even more

flexible with Canon's full-time manual

focusing which overrides the

autofocusing mode. Lenses with

this feature allow you to switch to

Film plane

manual focusing even in the AF

mode. You can keep looking through

the viewfinder and touch up the

Floating

focus manually without switching

the focus mode switch. Since the

focusing ring does not rotate during

autofocusing, we could make it

wider for better holding comfort and

easier manual focusing. Another

ergonomic design which lets you

convey your intentions quickly.

Full-time manual focusing comes in

two types. One is electronic manual

focusing where the rotation amount

of the focusing ring is detected and

the focusing motor is driven

electronically. The other type is

mechanical manual focusing where

the rotation of the focusing ring

adjusts the focus mechanically.

Ring 1

Manual focus ring

Roller

Ring 2

Focus key

Focusing lens group

AF Stop Feature

AF stop is featured on the EF

300mm f/2.8L IS USM, EF 400mm

f/2.8L IS USM, EF 500mm f/4L IS

USM, and EF 600mm f/4L IS USM

lenses. If something passes between

the camera and subject during

autofocusing, pressing the AF stop

buttons momentarily locks the AF

to prevent the focus from shifting

to the obstruction passing by.

After the obstruction is gone,

the focus is still maintained on the

subject and you can quickly resume

shooting. The AF stop buttons are

positioned at four locations around

the lens grip at the front of the lens

for easy access during both

horizontal and vertical shooting.

Dust- and Water-Resistant

Construction

The new EF 300mm f/2.8L IS

USM, EF 400mm f/2.8L IS USM,

EF 500mm f/4L IS USM, and

EF 600mm f/4L IS USM lenses are

highly dust- and water-resistant.

The switch panel, exterior seams,

and drop-in filter compartment have

rubber linings. Moving parts such

as the focusing ring and switches

are also designed to prevent water

and dust from entering. These lenses

can therefore be used in harsh

conditions without dust and water

getting inside.

The lens is equipped with a rubber

ring on the mount to improve its

dustproofing and waterproofing

characteristics. As the lens is

repeatedly mounted and detached,

the rubber ring will leave fine

abrasion marks on the outside

of the camera mount. This will not

affect operation.

Full-time mechanical manual focus mechanism

Rotor

USM Unit

Stator

Pressing spring

Focusing unit