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Light & Exposure Values

Read this section if you want a greater understanding of exposure.

You may want to read Sunny 16 Rule first.

Two Terms

Often, the terms exposure value and light value are used interchangeably.

However, they're different.

One is in "front" of the camera, and the other is "inside" the camera.

Light Values - In Front of the Camera

A light value (LV) is a measure of the luminance of a scene.

Luminance is the amount of light reflecting off of the subject.

In contrast, illumination is the amount of light falling on the subject.

Exposure Values - Inside the Camera

An exposure value (EV) is the exposure settings on your camera for a particular combination of light value and ISO.

Light Values ↔ ISO ↔ Exposure Values

Light values are linked to exposure values by way of the ISO setting of the camera.

Summary

• Light values are in front of the camera.

• Exposure values are inside the camera,

• With ISO linking a light value to an exposure value.

Camera   The Subject
Exposure Value ↔ ISO ↔ Light Value

Zero Point for

Light Values & Exposure Values

The zero point for light values and exposure values was arbitrarily set based on the luminance of a dim interior.

A dim interior has a light value of 0.

At ISO 100, the dim interior has an exposure value of 0.

One of the possible exposure settings is f/1 at 1 second, at ISO 100.

Camera  

The Subject

(Dim interior)

Exposure Value = 0

At ISO 100

Light Value = 0

All of the other exposure values below are derived from the above zero point.

Light Values Chart

Here's a chart of light values.

A chart for exposure values is below.

Go down to the Exposure Values Chart.

LV Value

Sunny 16 Exposure Subject

18

+3

- Bright reflections

17

+2

- White or very light colored/toned subject

in bright sunlight

16

+1

 

15

0

- Subject is medium colored/toned

in bright sunlight

14

-1

- Slightly overcast

13

-2

- Overcast

12

-3

- Heavy overcast

11

-4

- Sunset

- Open shade

10

-5

- Landscapes just after sunset or before sunrise

9

-6

- Landscapes 10 minutes after sunset/before sunrise

- Neon and lighted signs at night

- Stage shows with bright lighting

8

-7

- Times Square at night

- Store windows at night

- Fires at night

- Stadium lighting

- Interior with sunlight coming through window

- Interior with many florescent lights

7

-8

- Bright street at night

- Stage shows with average lighting

- Daytime interior with skylight

6

-9

- Fairs and amusement parks at night

- Daytime interior with windows & no direct sunlight

5

-10

- Night interior with bright lighting

4

-11

- Floodlighted buildings, monuments, fountains

- Holiday lighting at night (indoor or outdoor)

- Night interior with average lighting

- Candle-lighted close-ups

3

-12

- Street at night

2

-13

 

1

-14

 

0

-15

- Dim interior

-1

-16

 

-2

-17

 

-3

-18

- Rural landscape illuminated by a full moon

-4

-19

 

-5

-20

 

-6

-21

- Rural landscape illuminated by starlight

With the above light value chart, and the exposure value chart below, you can set any exposure.

You won't need a light meter.

How to Determine Exposures

1) Find the light value on the above light value chart.

2) Look for the same number in the exposure value columns on the exposure value chart below.

That is, if the light value is x, then the exposure value is also x.

Be sure to look for the exposure value number in the correct ISO column.

3) Use any of the exposure settings in the row for the exposure value number.

An Example

Let's say your photographing an elephant in bright sunlight.

The ISO on your camera is set to 200.

From the above light value chart, you find that the light value for a subject in bright sunlight is 15.

Here's the pertinent row from the above light value chart.

LV Value

Sunny 16 Exposure Subject

15

0

- Subject is medium colored/toned

in bright sunlight

You then use the exposure value chart below.

You locate the same number, 15, in the exposure value number column for ISO 200.

Here's the relevant row from the exposure value chart below.

Exposure Value Numbers Exposure Settings
100 200 400 800 1600 f/1 f/1.4 f/2 f/2.8 f/4 f/5.6 f/8 f/11 f/16 f/22
16 15 14 13 12 - - - 8000 4000 2000 1000 500 250 125

You can set your camera to any of the exposure settings in the row.

Same Amounts of Light

All of the exposure settings in each row allow the same amount of light to reach the camera sensor.

If you took a series of photographs at each of the settings in a row, the resulting photographs would look the same, exposure-wise.

Here are photographs made using the exposure settings from the same row as our example.

However

While the photographs may be the same "shade" exposure-wise, the photographs may not look the same in other ways.

Differences in depth-of-field may become apparent due to the varying lens openings.

Subject motion may be frozen or blurred depending on the shutter speed.

Exposure Values Chart

This is the exposure values chart.

Go up to the Light Values Chart.

Exposure Value Numbers Exposure Settings
100 200 400 800 1600 f/1 f/1.4 f/2 f/2.8 f/4 f/5.6 f/8 f/11 f/16 f/22
- - - - 18 - - - - - - - - - 8000
- - - 18 17 - - - - - - - - 8000 4000
- - 18 17 16 - - - - - - - 8000 4000 2000
- 18 17 16 15 - - - - - - 8000 4000 2000 1000
18 17 16 15 14 - - - - - 8000 4000 2000 1000 500
17 16 15 14 13 - - - - 8000 4000 2000 1000 500 250
16 15 14 13 12 - - - 8000 4000 2000 1000 500 250 125
15 14 13 12 11 - - 8000 4000 2000 1000 500 250 125 60
14 13 12 11 10 - 8000 4000 2000 1000 500 250 125 60 30
13 12 11 10 9 8000 4000 2000 1000 500 250 125 60 30 15
12 11 10 9 8 4000 2000 1000 500 250 125 60 30 15 8
11 10 9 8 7 2000 1000 500 250 125 60 30 15 8 4
10 9 8 7 6 1000 500 250 125 60 30 15 8 4 2
9 8 7 6 5 500 250 125 60 30 15 8 4 2 1"
8 7 6 5 4 250 125 60 30 15 8 4 2 1" 2"
7 6 5 4 3 125 60 30 15 8 4 2 1" 2" 4"
6 5 4 3 2 60 30 15 8 4 2 1" 2" 4" 8"
5 4 3 2 1 30 15 8 4 2 1" 2" 4" 8" 15"
4 3 2 1 0 15 8 4 2 1" 2" 4" 8" 15" 30"
3 2 1 0 -1 8 4 2 1" 2" 4" 8" 15" 30" -
2 1 0 -1 -2 4 2 1" 2" 4" 8" 15" 30" - -
1 0 -1 -2 -3 2 1" 2" 4" 8" 15" 30" - - -
0 -1 -2 -3 -4 1" 2" 4" 8" 15" 30" - - - -
-1 -2 -3 -4 -5 2" 4" 8" 15" 30" - - - - -
-2 -3 -4 -5 -6 4" 8" 15" 30" - - - - - -
-3 -4 -5 -6 - 8" 15" 30" - - - - - - -
-4 -5 -6 - - 15" 30" - - - - - - - -
-5 -6 - - - 30" - - - - - - - - -
-6 - - - - 60" - - - - - - - - -