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Lec. 9: Ch. 4 –The Camera and Photography\

Camera partsLenses for camerasControlling light

Photography as artPhotography as science

We are here

1

2

Daguerreotype

2Poe, 1848

Paris, 1838

Subject must remain still for minutes.

Silver droplets on polished silver.

3

I. Camera parts

1. Lens2. Shutter3. Diaphragm4. Focusing screen5. Film (or CCD

chip)

3

4

Camera parts

4

LensSheet film

holder

Bellows

Shutter &DiaphragmFocus

knob

This is an old-fashioned view camera.

5

Two common kinds of cameras

• Point and shootOne lens, viewfinder or liquid crystal display (LCD)

Point and shoot digital

• Single lens reflex (SLR)Interchangeable lensesSingle-lens reflex

LCD is not shown here

6

Focal length of lens determines magnification• Long focal length = telephoto • Short focal length = wide angle (bigger image)

50 mm normal lens

85 mm portrait lens

7

Some common lens focal lengths

40º

28 mm f. l.Wide angle

50 mm f. l.normal

135 mm f. l.telephoto

15º

65º

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Zoom lenses have adjustable focal length25 mm f.l. to 250 mm f.l = 10x zoomLens may have two fixed groups and two moving groups to hold focus constant while zooming

9

Camera parts

1. Lens, focal length2. Shutter (on the lens)3. Diaphragm (on the lens)4. Focusing screen or LCD5. Film (or CCD chip)

We are here

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Shutter speed

The shutter controls the duration of the light.

Common shutter speeds1/15 sec1/30 sec1/60 sec FACTORS OF 2 in light1/125 sec1/250 sec1/500 secEach change lets in half the light.

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F number determines amount of light

Big diameter lens = low f-number, like f-number 1.4

Heavy. Cost more! Works in low light and indoors.

Small diameter lens = big f-number, like f-number 3.5.

For outdoors, weigh less.

dF

opening ofdiameter length focalf ==

Example: 200 mm focal length / 25 mm opening = f-number 8

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F-number scale = factors of two in light1 Big opening

1.4

2

2.8

4

5.6 Factors of √2 apart

8

11

16 Small opening

Amount of light scales with area

Area scales with (diameter)2

more light

less light

Diaphragm has variable opening.

13

What f-number scale looks like

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Amount of light

f number Amount of light

1 100%1.4 50%2 25% or 1/42.8 1/84 1/165.6 1/32 8 1/64

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Why can images be out of focus?

F

fuzzyin focus

Rays of light diverge on either side of the focal point.

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What is depth of field?

Depth of field is how far objects can be apart and still be nearly in focus.

F

Are not in focus at the same place

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f-number 8 has more depth of field (less blur)than f-number 2

F

fuzzyin focus

big blursmall blur

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Equivalent exposure settings (same light)

¼ sec. lets subjects move

Background in focus(good depth of field)

1/250 sec. stops motion

Background out of focus

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Equivalent exposure settings

These combinations give the same lightf number shutter speed1.4 1/250 sports event, stop motion2 1/1252. 1/604 1/305.6 1/158 1/811 1/4 more depth of field

20

Which is best for a bird in a tree?

A. focal length 200 mmB. focal length 50 mm

21

Which gives more light?

A. f-number 4B. f-number 22

22

Which gives more light?

A. shutter speed 1/4 secB. shutter speed 1/16 sec

23

Which f-number gives half the light of f-4?

A. f-2B. f-2.8C. f-4D. f-5.6E. f-8

24

Which pair gives the same amount of light?

1/30 sec. and f number 4 and

a) 1/120 sec. and f-1b) 1/120 sec. and f-2c) 1/120 sec. and f-4

2525

Lec. 9: Ch. 4 –The Camera and Photography\

Camera partsLenses for camerasControlling light

Photography as artPhotography as science

We are here

25

2626

Siege of Yorktown, 1861James F. Gibson

2727

William Henry Jackson. Mountain of the Holy Cross. 1873.

Photography replaced paintingto describe the western US

Albert BierstadtLooking Down Yosemite ValleyOil painting

1865

2828

Wright Bros., 1903

Photography as proof.

Jackalope, 2003?

2929

Alfred Stieglitz1864-1946Photography as art

3030

Edward Steichen,1879-1973Glamour photography

31

Edward Weston

1886-1958

Compare to 15th

century painting with folded cloth

32

Imogen Cunningham1883-1976

Ansel Adams by Cunningham

33Fine focus

Harsh lighting

Soft focus (not out of focus)

Diffuse lighting

3434Ansel Adams1902-1984

nature photography

3535Ansel AdamsSnake River 1942