Reference Table
The commonly available numbers and some of their uses include:
| Wratten number |
Visible color | Filter factor or alternate designation |
F-Stops correction | Uses and characteristics |
|---|---|---|---|---|
| 1A | Called a skylight filter, this absorbs ultraviolet radiation, which reduces haze in outdoor landscape photography. | |||
| 2A | pale yellow | Absorbs ultraviolet radiation. longpass filter blocking wavelengths below 405 nm | ||
| 2B | pale yellow | Absorbs ultraviolet radiation, slightly less than #2A. longpass filter blocking wavelengths below 395 nm | ||
| 2C | Absorbs ultraviolet radiation. longpass filter blocking wavelengths below 390 nm | |||
| 2E | pale yellow | Absorbs ultraviolet radiation, slightly more than #2A. longpass filter blocking wavelengths below 415 nm | ||
| 3 | light yellow | Absorbs excessive sky blue, making sky look slightly darker in black and white images. longpass filter blocking wavelengths below 440 nm | ||
| 4 | yellow | longpass filter blocking visible wavelengths below 455 nm | ||
| 6 | light yellow | not a longpass filter | ||
| 8 | yellow | K2 | Absorbs more blue than #3. longpass filter blocking visible wavelengths below 465 nm | |
| 9 | deep yellow | Absorbs more blue than #8. longpass filter blocking visible wavelengths below 470 nm | ||
| 11 | yellowish-green | Color Correction. not a longpass filter | ||
| 12 | deep yellow | Minus blue filter; complements #32 minus-green and #44A minus-red. Used with Ektachrome or Aerochrome Infrared films to obtain false-color results. Used in ophthalmology and optometry in conjunction with a slit-lamp and a cobalt blue light to improve contrast when assessing the health of the cornea and the fit of contact lenses. longpass filter blocking visible wavelengths below 500 nm | ||
| 15 | deep yellow | Darkens the sky in black and white outdoor photography. longpass filer blocking visible wavelengths below 510 nm | ||
| 16 | yellow-orange | Performs like #15, but more so; longpass filter blocking visible wavelengths below about 520 nm | ||
| 18A | visually opaque | Based on Wood's glass, transmits small bands of ultraviolet radiation and infrared radiation. | ||
| 18B | very deep violet | Similar to 18A but with wider bands of transmittance in both the ultraviolet and infrared, a less 'pure' filter. | ||
| 21 | orange | G | Contrast filter for blue and blue-green absorption. longpass filer blocking visible wavelengths below 530 nm | |
| 22 | deep orange | Contrast filter, greater effect than #21. longpass filter blocking visible wavelengths below 550 nm | ||
| 23A | light red | longpass filter blocking visible wavelengths below 550 nm | ||
| 24 | red | Used for color separation of Kodachrome tranparency film, complements #47B and #61. longpass filter blocking visible wavelengths below 575nm. Red for 'Two Colour Photography' (daylight or tungsten). White flame arc tri-color projection. | ||
| 25 | red tricolor | A | Used for color separation and infrared photography longpass filter blocking below 580 nm. | |
| 26 | red | longpass filter blocking below 585 nm | ||
| 29 | deep red | F | Used for color separation, complements #47 and #61. In black and white outdoor photography makes blue skies look very dark, almost black. In infrared photography, blocks much visible light, increasing the effect of the infrared frequencies on the picture. longpass filter blocking below 600 nm. | |
| 32 | magenta | Minus-green. Complements #12 minus-blue and #44A minus-red. | ||
| 34A | violet | Used for minus-green and plus-blue separation. | ||
| 38A | blue | Absorbs red, some UV and some green light. | ||
| 40 | light green | Green, for two color photography (tungsten). | ||
| 44 | light blue-green | minus-red filter with much UV absorption. | ||
| 44A | light blue-green | minus-red, complements #12 is minus-blue and #32 minus-green. | ||
| 47 | blue tricolor | Used for color separation. Complements #29 and #61. | ||
| 47A | light blue | By removing lots of light that is not blue, blue and purple objects show a broader range of colors. Used for medical applications that involve making dyes fluoresce. | ||
| 47B | deep blue tricolor | Used for color separation. It is also commonly used to calibrate video monitors while using SMPTE color bars. | ||
| 50 | deep blue | |||
| 56 | light green | |||
| 57 | green | Green for 'Two Colour Photography' (daylight). | ||
| 58 | green tricolor | B | Color separation. | |
| 60 | green | Green for two color photography' (tungsten). | ||
| 61 | deep green tricolor | N | Color separation, complements #29 and #47. | |
| 70 | red | Used for color separation and infrared photography longpass filter blocking below 650 nm. | ||
| 80A | blue | 4 | 2 | Color Conversion. Raises the color temperature, causing a 3200 K tungsten-lit scene to appear to be daylight lit, approximately 5500 K. This allows use of a daylight balanced film with tungsten lighting. |
| 80B | blue | 3 | 1+2/3 | Similar to 80A; 3400 K to 5500 K. |
| 80C | blue | 2 | 1 | Similar to 80A; 3800 K to 5500 K. Typically used so that old-style flashbulbs can be used on a daylight film. |
| 80D | blue | 1.5 | 1/3 | Similar to 80A; 4200 K to 5500 K. |
| 81A | pale orange | 1.4 | 1/3 | Warming filter to decrease the color temperature slightly; this can also be used when shooting tungsten type B film (3200 K) with 3400 K photoflood lights. The opposite of 82A. |
| 81B | pale orange | 1.4 | 1/3 | Warming filter, slightly stronger than 81A. The opposite of 82B. |
| 81C | pale orange | 1.5 | 1/3 | Warming filter, slightly stronger than 81B, opposite of 82C. |
| 81D | pale orange | Warming filter, slightly stronger than 81C. | ||
| 81EF | pale orange | 1/3 | Warming filter, stronger than 81D. | |
| 82A | pale blue | 1.3 | 1/3 | Cooling filter to increase the color temperature slightly. The opposite of 81A. |
| 82B | pale blue | 1.4 | 2/3 | Cooling filter, slightly stronger than 82A and opposite of 81B. Can also be used when shooting tungsten type B film (3200 K) with household 100 W electric bulbs (2900 K). |
| 82C | pale blue | 1.5 | 2/3 | Cooling filter, slightly stronger than 82B and opposite of 81C. |
| 85 | amber | 1.5 | 2/3 | Color conversion, the opposite of the 80A; this is a warming filter that takes an outdoor scene lit by sunlight (which has a color temperature around 5500 kelvins) and makes it appear to be lit by tungsten incandescent bulbs around 3400 K. This allows an indoor balanced film to be used to photograph outdoors. These filters were used in Super 8 movie cameras that were designed to use Tungsten film. |
| 85B | amber | 1.5 | 2/3 | Similar to 85; converts 5500 K to 3200 K. |
| 85C | amber | 1.5 | Similar to 85; converts 5500 K to 3800 K. | |
| 85N3 | amber | Neutral density of 1 stop + color conversion, the opposite of the 80A; this is a warming filter that takes an outdoor scene lit by sunlight (which has a color temperature around 5500 kelvins) and makes it appear to be lit by tungsten incandescent bulbs around 3400 K. This allows an indoor balanced film to be used to photograph outdoors. | ||
| 85N6 | amber | Neutral density of 2 stops + color conversion, the opposite of the 80A; this is a warming filter that takes an outdoor scene lit by sunlight (which has a color temperature around 5500 kelvins) and makes it appear to be lit by tungsten incandescent bulbs around 3400 K. This allows an indoor balanced film to be used to photograph outdoors. | ||
| 85N9 | amber | Neutral density of 3 stops + color conversion, the opposite of the 80A; this is a warming filter that takes an outdoor scene lit by sunlight (which has a color temperature around 5500 kelvins) and makes it appear to be lit by tungsten incandescent bulbs around 3400 K. This allows an indoor balanced film to be used to photograph outdoors. | ||
| 87 | opaque | Passes infrared but not visible frequencies. blocks wavelengths below 740 nm | ||
| 87A | opaque | Passes infrared but not visible frequencies. blocks wavelengths below 880 nm | ||
| 87B | opaque | Passes infrared, blocks visible frequencies. blocks wavelengths below 820 nm | ||
| 87C | opaque | Passes infrared, blocks visible frequencies. blocks wavelengths below 790 nm | ||
| 88 | opaque | Passes infrared, blocks visible wavelengths below 700 nm. | ||
| 88A | opaque | Passes infrared, blocks visible frequencies. below 720 nm. | ||
| 89B | near-opaque red | R72 | Passes infrared, longpass filter blocking visible wavelengths below 690 nm (very deep red). Aerial photography is one use. | |
| 90 | dark grayish amber | Used for viewing scenes without color before photographing them, in order to assess the brightness values. Not used for actual photography. | ||
| 92 | red | color densitometry. longpass filter blocking visible wavelengths below 625 nm | ||
| 93 | green | color densitometry. | ||
| 94 | blue | color densitometry. | ||
| 96 | gray | varies | neutral density filter. Blocks all frequencies of visible light approximately evenly, making scene darker overall. Available in many different values, distinguished by optical density or by filter factor. | |
| 98 | blue | Like a #47B plus a #2B filter. | ||
| 99 | green | Like a #61 plus a #16 filter. | ||
| 102 | yellow-green | Color conversion; makes a barrier-level type photocell respond as a human eye would. | ||
| 106 | amber | Color conversions; makes an S-4 type photocell respond as a human eye would. |
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