Canon EF 35-80mm f/4-5.6 III Lenzen Handleiding - Pagina 12

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Canon EF 35-80mm f/4-5.6 III Lenzen Handleiding

Large, Fully Electronic

Mount System

Focus Preset

The conventional interface between

the lens and camera body was

With the focus preset feature, you

mechanical, with the use of engaging

can set the desired focusing distance

levers and gears. This method caused

in memory and later instantly focus

the lens at that distance. Normal

physical problems such as wear and

rattle. It was limited and more diverse

picture-taking and focusing are

information could not be exchanged.

possible even while focus preset has

Canon EF lenses do not use such

been set. At a soccer game, for

mechanical links at all. About 50

example, you can preset the focus

items of information are exchanged

for the goal. You can focus normally

as digital signals between the lens

while the player approaches the goal,

and camera in real time. This enables

then when the ball is shot into the

goal, you can obtain instant focus.

high-speed and high-precision

control. And since the lens mount

diameter is an ample 54mm, special

lenses such as large-aperture lenses

and TS-E lenses can be used. The EF

Fluorite (CaF2) and UD-Glass

mount is an advanced interfacing

system with infinite possibilities.

The refraction of light differs

depending on the wavelength.

Built-In Motor and EMD

The point of focus, therefore, differs

depending on the different

Canon EF lenses (except TS-E

wavelengths or colours. When the

and MP-E lenses) have a built-in

different wavelengths are focused

AF motor. Compared with camera

at different points, the colours look

body-based AF motors, lens-based

smeared. This is called chromatic

motors have driving energy with

aberration. The longer the focal

lower transmission loss. The optimum

length, the more pronounced

AF motor for the particular lens can

chromatic aberration becomes.

also be selected and installed. The AF

Usually, an achromatic element

operation is therefore quick, quiet, and

is used in a lens to correct chromatic

highly precise. The lenses also have an

aberration. However, normal optical

EMD (Electromagnetic Diaphragm)

glass can only be corrected for

to control the aperture electronically.

two primary spectral colours.

The aperture can be set either with

An exception to this limitation

an electronic dial or with the electronic

is Fluorite, an ideal material.

pulse signal sent according to the

Fluorite, which is crystalline, has

exposure reading. Aperture control

abnormally low refraction and low

precision is therefore unmatched.

dispersion characteristics, which

optical glass cannot achieve. It also

Ring-type USM

has anomalous dispersion from the

green to blue wavelengths. Canon

developed production technologies to

manufacture Fluorite. By incorporating

Fluorite in lenses, the points of focus

of the three primary spectral colours

of red, green, and blue all meet at one

point for ideal correction of chromatic

EMD

aberration. There is also UD-glass,

which is a special type of optical glass

Built-in motor and EMD

whose properties nearly match those

of Fluorite. The effect of two UD-glass

elements is equivalent to having one

Fluorite element. And one super

Inner Focusing and

UD-glass element gives almost the

Rear Focusing

same effect as one Fluorite element.

An inner focusing lens has the

focusing lens group(s) in front of

Comparison of optical characteristics

between optical glass and Fluorite

the diaphragm, while a rear focusing

lens has the focusing lens group(s)

behind the diaphragm. Both focusing

Red

systems allow the focusing lens group

Glass

to be small. This minimises the load

Blue

on the actuator which drives the

Anomalous

autofocus. In turn, the AF speed is

dispersion

faster. The whole optical system can

also be made more compact.

Red

Also, since the lens does not rotate

Blue

during focusing, the effects of a

Fluorite

circular polarising filter or gelatin

filter remain intact.

Fluorite and UD glass

Description of Lens Designation

The lens designations follow a standard format to identify the lens.

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

Focal length:

Maximum aperture:

Special Function:

USM: Indicates

Indicates the focal

Indicates the lens's

Any special

that the lens uses

length range from

maximum aperture.

feature such as an

an Ultrasonic

the shortest to

(See below for

image stabilizer,

Motor for

longest length.

details.)

macro feature, etc.,

autofocusing.

(See below for

is indicated.

(See page 19 for

details.)

Focal Length

maximum aperture (the f-number

is larger) allows the lens to be

A focal length of 50mm is closest

more compact and light. Single

to what the eye sees. This focal

focal length lenses have only one

length is used as a reference point

maximum aperture while zoom

for lens categories. For example,

lenses may have two, one for each

lenses with a shorter focal length

end of the focal length range. For

are called wide-angle lenses, while

example, a EF 28-80mm f/3.5-5.6

those with a longer focal length

lens has a maximum aperture of

are called telephoto lenses. Single

f/3.5 at 28mm and f/5.6 at 80mm.

focal length lenses have only one

focal length, while zoom lenses

Aperture and Shutter Speed

have a range of focal lengths.

(When EF lenses are used with the

Under the same light level, if the

EOS IX, the focal length

aperture opening is made larger by

corresponds to 1.25 times that

one step, the shutter speed can be

indicated for 35mm cameras.)

increased by one step. For example,

if an aperture of f/5.6 and shutter

Angle of View

speed of 1/60 sec. are set,

adjusting the aperture to f/4 will

This indicates how much coverage

enable a shutter speed of 1/125

of the scene you can see through

sec. to be used. An aperture of

the lens. Telephoto lenses have

f/2.8 will allow a faster shutter

a narrower angle of view than

speed of 1/250 sec. while the same

wide-angle lenses.

exposure level is maintained.

Angle of View and Perspective

Depth of Field

Perspective refers to the distance

Normally, there is only one point of

between the near and far objects

optimum focus. However, we often

that you can see at the same time.

see objects in front of or behind this

When the angle of view is wide

point also in focus. This is made

(with a shorter focal length),

possible by a wide depth of field.

the perspective becomes more

apparent. And with a narrow angle

Depth of Field with the

of view (with a longer focal length),

Aperture and Focal Length

the perspective becomes less

apparent. The image also becomes

The depth of field is mainly

more compressed, with the far

determined by the lens focal length,

objects looking like they are right

aperture and subject distance.

behind the nearer objects.

For example, if a wide-angle lens

is used at the minimum aperture,

Maximum Aperture

almost everything in the picture will

be in focus. However, if a telephoto

This indicates the speed of the

lens is used at maximum aperture,

lens. A fast lens has a large

the background will be really

maximum aperture allowing more

blurred, making the subject in

light to enter. The smaller the

focus stand out.

maximum aperture's f-number,

the larger the aperture opening is.

A larger maximum aperture makes

the image look brighter and easier

to see through the viewfinder.

You can also use a faster shutter

speed or obtain better background

blur. On the other hand, a smaller

Canon EF Lens accessories

General Purpose Filters

Loupe 8x & 4x

for Black-and-White or

Colour Film

Sky (1A), Haze (UV-1), ND (03 • 0.6)

• 52mm • 58mm • 72mm

Conversion Filters for

Colour Film

The Canon Loupe 4x is a high-

80A, 80B, 85, 85B, FCB, FCD

performance magnifier for viewing

• 52mm • 58mm • 72mm

the entire picture area (24 x 36mm)

of a 35mm-format slide or negative.

General Purpose Filters for

With three lens elements in three

Black-and-White Film

groups, chromatic aberration and

Yellow 2, Green 11, Orange 15,

distortion are effectively corrected to

Red 25A

give crystal-clear images. Eye fatigue

• 52mm • 58mm • 72mm

is not a problem even after prolonged

use. Loupe 8x is another magnifier

Softmat Filters

for viewing the entire picture area,

but with special emphasis on a

Softmat filters mildly soften the

24mm-diameter area at the centre.

focus for flattering portraits and

dreamy landscapes. These filters

The four lens elements in four groups

attain high performance and a high

utilise the effect of diffraction which

occurs between light passing through

magnification. All elements have

Super Spectra Coating to make

the transparent part and light

image viewing clear enough for you

passing through the coated part.

Use Softmat No. 1 filter for a gentle

to effectively check the quality of

photos taken with EF lenses. These

soft-focus effect, and Softmat No. 2

two loupes can make your evaluation

for a stronger effect

of photos more accurate.

No.1, No.2

• 52mm • 58mm

Drop-in Filters

Warming Filters for

Drop-in Filters PL-C

Colour Film

Drop-in Filters PL-C

can be rotated from

81A, 81B

the outside without

• 52mm • 58mm • 72mm

removing them from the lens for

precise control. The 48mm

Circular Polarising Filters PL-C

PL-C filter can be used with the

Polarising filter enhances picture

following lenses – EF 200mm

quality by blocking harmful reflected

f/1.8L USM and EF 1200mm

light. Use it to reduce polarised

f/5.6L USM; the 52mm PL-C filter

light reflections from glass and

is designed for use with the

water surfaces or to improve colour

EF 300mm f/2.8L IS USM,

saturation. Simple to use, circular

EF 400mm f/2.8L IS USM,

polarising filters (such as Canon's

EF 500mm f/4L IS USM and EF

PL-C) polarise light circularly, rather

600mm f/4L IS USM.

than linearly, so it does not interfere

Drop-in Gelatin

with autofocus or TTL light metering.

Filter Holders

• 52mm • 58mm • 67mm • 72mm

These glass-backed

• 77mm (Type II)

holders accept up

to three commercially available

cut-to-size gelatin filters for

rear-insertion lenses. A 48mm

holder is provided standard with

EF 200mm f/1.8L USM and EF

1200mm f/5.6L USM; and a

52mm holder, with

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.

Drop-in Screw

Filter Holders With

Protect Filters

The enclosed regular

filter can be exchanged with other

commercially available screw-type

filters. Note that only filters with

correct filter frame thickness can

be mounted on the lens.

• 48mm • 52mm

Only Canon Filters are guaranteed for use

with EF lenses.

Gelatin filter Holders III & IV

Gelatin Filter

Holder III

Holder IV

Gelatin Filter Holder III uses 3 x 3

inch gelatin filters and Gelatin

Filter Holder IV uses 4 x 4 inch

gelatin filters. Holders III and IV

both provide extension hoods

and 52mm, 58mm, 67mm, 72mm

and 77mm adapters. Refer to the

EF Lens Accessory Table for

information on lens combinations.

• 52mm • 58mm • 67mm

• 72mm • 77mm

• Adapter III for EF 50mm 1: 1.4