Filter factors

Conversion Filters are intended for use whenever significant changes in the color temperature of the illumination are required (e.g., daylight to artificial light). The filter may be used in front of the light source or camera lens.

Conversion Filters for Color Films

Filter Color

Filter Number

Exposure Increase
In Stops *  

Conversion
(K)

Mired
Shift
Value

Blue

80A

2

3200 to 5500

-131

80B

1 2/3

3400 to 5500

-112

80C

1

3800 to 5500

-81

80D

1/3

4200 to 5500

-56

Amber

85C

1/3

5500 to 3800

81

85

2/3

5500 to 3400

112

85N3

1 2/3

5500 to 3400

112

85N6

2 2/3

5500 to 3400

112

85N9

3 2/3

5500 to 3400

112

85B

2/3

5500 to 3200

131

Light-balancing filters enable the photographer to make minor adjustments in the color quality of illumination to obtain cooler (bluer) or warmer (yellower) color rendering. When using a color-temperature meter to determine the color temperature of prevailing light, or where you know the color temperature, use the following table to convert the prevailing temperature to either 3200 K or 3400K.

Light Balancing Filters

Filter Color

Filter Number

Exposure Increase
In Stops *

To obtain
3200K 
from:

To obtain
3400K 
from:

Mired Shift Value

Bluish

82C + 82C

1 1/3

2490 K

2610 K

-89

82C + 82B

1 1/3

2570 K

2700 K

-77

82C + 82A

1

2650 K

2780 K

-65

82C + 82

1

2720 K

2870 K

-55

82C

2/3

2800 K

2950 K

-45

82B

2/3

2900 K

3060 K

-32

82A

1/3

3000 K

3180 K

-21

82

1/3

3100 K

3290 K

-10

Yellowish

81

1/3

3300

3510 K

9

81A

2/3

3400

3630 K

18

81B

1 2/3

3500

3740 K

27

81C

2 2/3

3600

3850 K

35

81D

3 2/3

3700

3970 K

42

81EF

2/3

3850

4140 K

52

Neutral Density Filter

Neutral Density

Percent
Transmittance

Filter Factor

Increase
In Exposure
(Stops)

0.1

80

1.25

1/3

0.2

63

1.5

2/3

0.3

50

2

1

0.4

40

2.5

1 1/3

0.5

32

3

1 2/3

0.6

25

4

2

0.7

20

5

2 1/3

0.8

16

6

2 2/3

0.9

13

8

3

1.0

10

10

3 1/3

2.0

1

100

6 2/3

3.0

0.1

1,000

10

4.0

0.01

10,000

13 1/3

Color Compensating Filters

Nominal
Peak
Density

Yellow
(Absorbs
Blue)

Exposure
Increase
In Stops*

Magenta
(Absorbs
Green)

Exposure
Increase
In Stops *

Cyan
(Absorbs
Green)

Exposure
Increase
In Stops*

.025

CC025Y

----

CC025M

----

CC025C

----

.05

CC05Y

----

CC05M

1/3

CC05C

1/3

.10

CC10Y

1/3

CC10M

1/3

CC10C

1/3

.20

CC20Y

1/3

CC20M

1/3

CC20C

1/3

.30

CC30Y

1/3

CC30M

2/3

CC30C

2/3

.40

CC40Y 

1/3

CC40M

2/3

CC40C

2/3

.50

CC50Y

2/3

CC50M

2/3

CC50C

1

Nominal
Peak
Density

Red
(Absorbs
Blue 
Green )

Exposure
Increase
In Stops*

Green
(Absorbs
Blue and
Red)

Exposure
Increase
In Stops*

Blue
(Absorbs
Red and
Green )

Exposure
Increase
In Stops*

.025

CC025R

----

CC025G

----

CC025B

----

.05

CC05R

1/3

CC05G

1/3

CC05B

1/3

.10

CC10R

1/3

CC10G

1/3

CC10B

1/3

.20

CC20R

1/3

CC20G

1/3

CC20B

2/3

.30

CC30R

2/3

CC30G

2/3

CC30B

2/3

.40

CC40R

2/3

CC40G

2/3

CC40B

1

.50

CC50R

1

CC50G

1

CC50B

1

* All values are approximate. For critical work, when using more than one filter, check by practical test.