Those of you who have been involved with photography for some time may have heard the terms "Foot-candles" or "LUX". You may find these referred to on some light meters. These measurements are used in the film industry, television and industrial lighting. There is a relationship between these numbers and EV numbers. Since you've already learned about EV numbers, this section will allow you to edify and amaze your friends with your knowledge of light!

RELATIONSHIP

Is there any intuitive relationship between EV, Foot-candles and LUX? The answer is "not really". EV numbers are a linear progression that is convenient to use for memorization of relative light levels. Footcandles and LUX proceed in a doubling manner, which better illustrates the doubling (or halving) of light at each step. To get to LUX, simply multiply the foot-candles by 11. The table below better represents the relationship:

Exposure Value

EV ISO 100

Footcandles

LUX

-3

.03

.31

-2

.06

.63

-1

.12

1.3

0

.23

2.5

1

.46

5

2

.93

10

3

1.9

20

4

3.7

40

5

7.4

80

6

15

160

7

30

320

8

60

640

9

120

1300

10

240

2600

11

480

5100

12

950

10000

13

1900

20000

14

3800

41000

15

7600

82000

16

15000

160000

17

30000

330000