Canon T3 Brochure télécharger pdf (Page 21)

usa.canon.com/eos

EF LENSES

15mm Fisheye

FOCAL LENGTH COMPARISON

Floating System

Typical lenses correct for optical aberrations

only at commonly used focusing distances. Not

surprisingly, at other focusing distances, espe-

cially close range, aberrations can compromise

image quality. Rather than using fixed spacings,

Canon’s floating system dynamically varies

the gap between key lens elements based

on focusing distance. Most aberrations are

effectively suppressed throughout the focusing

range, assuring high image quality in all

shooting situations.

Circular Aperture

Canon lenses featuring circular aperture

diaphragms employ curved blades to create

a smoothly rounded opening as the lens is

stopped down. As a result, most out-of-focus

background highlights are rendered as

natural-looking rounded shapes rather than

as distracting polygons. These lenses deliver

smooth, consistent stop-down action (even at

14.0 fps), near-silent operation and excellent

optical characteristics.

Inner and Rear Focusing

An inner focusing lens has the focusing lens

group(s) in front of the diaphragm, while a

rear focusing lens has the focusing lens group(s)

behind the diaphragm. Both designs allow for

compact optical systems that produce faster AF.

And because the front of the lens does not rotate

to focus, filter orientation remains constant.

AF Stop Feature

Pressing the AF Stop button (featured on several

EF IS telephoto lenses) momentarily locks the

AF to help prevent the focus from shifting to a

passing obstruction. After the obstruction has

cleared, the focus will still be on the subject, and

you can quickly resume shooting. AF Stop buttons

are positioned at four locations around the lens

grip for easy access.

Full-Time Manual Focusing

Canon EOS cameras with EF lenses deliver

impec-cable AF precision. Manual focusing

capability, nevertheless, can enhance

flexibility. Canon EF lenses with full-time

manual focusing enable the photographer to

manually tweak focus without switching out

of AF mode. Since AF action does not cause

the focusing ring to turn, it can be made wider

for improved grip and comfort.

Specialty Lenses

Fisheye — With its unique focal length range,

the EF 8–15mm f/4L Fisheye USM is the world’s

widest fisheye zoom lens. It delivers 180°

diagonal angle of view images for all EOS SLR

cameras with imaging formats ranging from

full-frame to APS-C, and provides 180° circular

fisheye images for full-frame EOS models. This

new Canon lens has a wide zoom range feature

that provides a truly elevated level of creativity

and performance for users shooting artistic

compositions or panoramic landscapes, as

well as astronomy and sports.

EF-S lenses — Designed for the Canon EOS 7D,

EOS 60D and all EOS Rebel models with APS-C

sized sensors with a 1.6x crop factor, Canon’s

EF-S lenses take advantage of the camera

sensor’s smaller size to help deliver optimized

performance in compact, lightweight designs.

EF-M lenses — Even more compact, and

designed to complement the new EF-M lens

mount found on the EOS M Digital Camera,

EF-M lenses bring superb EOS optics and

performance to an even smaller package.

TS-E — TS-E lenses are capable of tilt and

shift movements, which bring many of the

advantages of technical view cameras to the

EOS System. Tilt movements alter the angle of

the plane of focus between the lens and film

plane, making broad depth-of-field possible

even at larger apertures; shift movements

slide the lens’s optical axis along the film/

sensor plane, enabling photographers to

correct or alter perspective at almost any angle.

Macro — Canon’s EF lens lineup has a number

of options for true close-up and macro photog-

raphy. With five macro lenses for precision,

and three screw-on close-up lenses for conve-

nience—in addition to the Life-Size Converter EF

and two Extension Tubes—Canon’s macro lenses

and close-up accessories can uncover detail that

is nearly impossible for the unaided human eye

to detect.

EF Mount

The Canon EF and EF-M mount are much more than

simply a way to attach a lens to a camera body. As

the communication conduit between camera and

lens, this fully electronic mount enables high-

speed autofocus, precise aperture control and

preview, makes automatic compensation with

lens extenders possible and can communicate

data such as focal length, lens model, even

serial number for in camera processing and

recording. Ready for the future, the EF mount

offers both forward and backward compatibility

Dust- and Water-Resistant

Construction

Most L-series EF

telephoto lenses are

highly dust- and

water-resistant

thanks to rubber seals

at the switch panels,

exterior seams, drop-

in filter compartments

and lens mounts.

Moving parts, such as

the focusing ring and

switches, are also designed to help keep out

environmental contaminants, providing reliable

performance under harsh conditions.

Reverse tilt and shift greatly reduces the range on which focus-

ing is possible.

With a normal lens With a TS-E lens

Astigmatism

Floating Effect

(TS-E 24mm f/3.5L)

Closest

shooting

distance

TS-E 24mm f/3.5L Floating System

Floating

Focal plane

The lens’s tilt mechanism is used to achieve a pan focus effect

that allows focusing all the way back.

Shift was used to adjust the image to keep the building

perpendicular all the way to the top.

Without using shift causes the image of the building to lean in

at the top.

Tilt Movements –

Using a normal lens, shallow or deep focus is

controlled by the size of the aperture used to adjust depth-of-

field. Canon TS-E lenses can help achieve this by the tilting of

the lens barrel in relationship to the focal and subject planes.

This allows for the appearance of extremely deep focus even at

wide open apertures, and shallow focus at smaller apertures.

Shift Movements – By keeping the camera level, and

using the shift function to raise the lens instead, this

perspective effect can be corrected. With the camera’s

focal plane set parallel to the building, shifting the lens

upward will obtain a more rectangular-looking building.

About Macro Magnification

A life-size macro lens—that

is, a 1x magnification—

records an image on film at

its actual size. If you’re

photographing fruits, for

example, and it has a diam-

eter of 1 in., it will occupy 1

in. of your actual slide or

negative. With a digital

SLR, at 1.0x magnification,

the image projected onto

your camera’s sensor will

likewise be the same size at

the sensor plane as the

actual subject itself. Other

macro lenses have lower or

higher magnifications. A

lens with 0.5x magnifica-

tion will produce an image

on film that is half the

size of the actual subject.

Your 1 in. fruit then would

only occupy 0.5 in. on film.

In the other direction, a 5x

magnification lens will con-

vert the 1-in. fruit to a 5-in.

diameter image. Since the

entire image won’t fit in the

frame of your film, you will

have an enlarged image of

a detail of the fruit.

Magnification is not the

same as focal length. A

50mm lens and a 180mm

might both be macro lenses

with, for example, 1.0x

magnification. The advan-

tage of the longer lens is

that it allows greater dis-

tance from a subject, while

allowing the same magnifi-

cation in the final image. The 180mm lens is ideal for shoot-

ing tiny subjects without disturbing them; the 50mm is bet-

ter choice for copying flat documents.

0.5x

1.0x

0.25x

5.0x

3.0x

EF 24mm f/1.4L II USM •f/2.8 •1/30 sec.

14mm 17mm 20mm 24mm 28mm 35mm 50mm 70mm

85mm 100mm 135mm 200mm 300mm 400mm 500mm 600mm 1200mm

Depth-of-field with tilt movements

Plane of optimum focus

Film plane

Using Tilt Movements to Focus an Oblique Subject Plane

Using Shift Movements to Focus Tall Building

TS-E Movements

Tilt Movements alter the angle of the plane of focus between the lens and focal plane, and Shift Movements move the lens’s

optical axis in parallel.

180°

114°

104° 94° 84°

75° 63° 46° 34°

28° 30' 24° 18° 12° 8° 15' 6° 10' 5° 4° 10' 2° 5'

EF 8–15mm f/4 Fisheye USM

•

f/4

•

1024 sec.

EF 8–15mm f/4 Fisheye USM

•

f/5.6

•

1/200 sec.

Focal Length: 8 mm Approx. 10 mm

Approx. 12 mm Approx. 15 mm

Full size

Circular fisheye

APS-C

Full-frame fisheye

APS-H

Full-frame fisheye

Full size

Full-frame fisheye

The diagram below shows the relationship between each

image size and a 180˚ angle of view for each focal length.

*The red circle for each forcal length is the size of a 180˚ angle of

view on the image plane.

with new lens technologies such as USM and

Hybrid IS—and new optical designs, such as EF-S

lenses and Cinema EOS lenses as they are devel-

oped by Canon. Similarly, the EF-M mount, found

on the new EOS M Digital Camera, offers all the

same communication points as the EF mount, and

is compatible with all EF and EF-S lenses when

used with an optional adapter.

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 43 44

Commentaires sur ces manuels

Pas de commentaire

Canon T3 Brochure Page 21

Commentaires sur ces manuels

Produits connexes et manuels pour Caméscopes Canon T3