photography reference - christopher rake

Over the years I've gather various tidbits of photography information that I've found useful. The material is compiled from a large number of sources, books, online reference, etc. If you have any suggestions (or corrections!) please contact me.

Sensor Sizes
35mm frame: 24mm x 36mm
10D sensor: 15.1mm x 22.7mm

Crop Factors
35mm: 1.0
Canon 1Ds: 1.0
Canon 1D: 1.3
Nikon D100/D2H: 1.5
Canon 10D/300D: 1.6

Luminance vs. Illuminance
Luminance = Amount of light reflected/emitted from a subject (what a camera light meter measures)
Illuminance = Amount of light falling on a subject

Light Value (Lv)
Lv = Log2(BK)
B = Subject Luminance
K = 86.2 is B is candela/sq foot.
K = 8.0 if B is candela/sq meter

Light Value Chart ( light reflecting off an ideal subject (18% grey card) except for "emitted")
17
Rarely seen in nature
5
Average interior or auditorium
16
Bright sunlight off of sand or snow
4
Christmas or candle lights
15
Bright hazy sunlight
3
Fireworks (emitted)
14
Weak hazy sunlight
2
Lightning from a distance (emitted)
13
Bright cloudy day
1
City skyline at night (emitted)
12
Overcast day
0
Dim ambient light
11
Shade on a bright day or during sunrise/set
-1
Really dim ambient light
10
Dusk or dawn
-2
Full moon off of sand or snow
9
Late dusk or early dawn
-3
Full moon
8
Times square at night
-4
Half moon
7
Brightly lit street
-5
Crescent moon
6
Bright interior
-6
Starlight

f-number
Diameter of lens aperature with respect to focal length
Example: f/4 means aperature diameter is 1/4 the focal length

f-stop
Each stop = halving of light
Powers of square root of 2 - amount of light (area) is function of diameter squared
Examples: f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22
"Odd" values like f/3.5 are common

Shutter Speed
Length of time shutter is open
Examples: 1/30, 1/60, 1/250, etc.

Exposure Value (Ev)
Ev = log2(Aperature^2/Shutter Speed)
Ev0 = f/1.0 at 1 second
An Ev increase of 1 = halfing of light admitted

Exposure Value Chart - Ev and Corresponding Shutter/Aperature Settings
Aperature
Shutter
f/1
f/1.4
f/2
f/2.8
f/4
f/5.6
f/8
f/11
f/16
f/22
f/32
1 sec
0
1
2
3
4
5
6
7
8
9
10
1/2
1
2
3
4
5
6
7
8
9
10
11
1/4
2
3
4
5
6
7
8
9
10
11
12
1/8
3
4
5
6
7
8
9
10
11
12
13
1/15
4
5
6
7
8
9
10
11
12
13
14
1/30
5
6
7
8
9
10
11
12
13
14
15
1/60
6
7
8
9
10
11
12
13
14
15
16
1/125
7
8
9
10
11
12
13
14
15
16
17
1/250
8
9
10
11
12
13
14
15
16
17
18
1/500
9
10
11
12
13
14
15
16
17
18
19
1/1000
10
11
12
13
14
15
16
17
18
19
20
1/2000
11
12
13
14
15
16
17
18
19
20
21
1/4000
12
13
14
15
16
17
18
19
20
21
22

Film Speed
Defined by International Standard Organization (ISO) 5800:1987
Specific to film, but adopted by digital cameras
Examples: ISO 100, ISO 200, ISO 400, etc.
Double ISO doubles sensitivity to light thus requiring half as much light for proper exposure
Higher ISO = more grain (film) or more noise (digital)

Correct Exposure: E = L + S
E = Exposure Value (Ev)
L = Light Value (Lv)
S = Speed Value (Sv) = Log2(ISO Speed / 100)
For ISO 100: Ev = Lv, yields proper exposure
ISO 200: Ev = Lv + 1, ISO 400: Ev = Lv + 2, etc.

Exposure Latitude
The range of brightness a film/sensor can record
Human Eye: 11-30 Lv
Print Film: 5-7 Lv
Slide Film: 3-5 Lv
Digital (in-camera processed): 3-5 Lv
Digital (raw): 4-6 Lv
Exposure outside of this range results in loss of shadow detail or blown highlights. If the subject's luminance range falls within the exposure latitude, the entire subject can be properly exposed.

Light Temperature

Temperature
Scene
10,000K
High altitude, clear blue day
9,000K
Rainy Daylight
7,000K
Overcast Daylight
5,600K
Daylight Standard
5,000K
Noon Daylight, Direct Sun
4,500K
Electronic Flash (4500K-6000K)
4,000K
Flurorescent (4000K-5000K)
3,500K
Sunrise / Sunset
3,200K
Indoor "White" Light Standard, Quartz (Tungsten-Halogen)
2,500K
Household Lightbulbs
2,000K
Early Sunrise
1,200K
Candlelight

 



All images and web content © Christopher Rake 2004-5