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11
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
8
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
10
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.
11
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
12
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
14
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.
16
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
17
f-number 8 has more depth of field (less blur)than f-number 2
F
fuzzyin focus
big blursmall blur
18
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
19
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
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Which gives more light?
A. f-number 4B. f-number 22
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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