FILTERS FOR BLACK AND WHITE PHOTOGRAPHY
A YELLOW filter absorbs violet and some blue.
A MINUS BLUE filter absorbs violet and blue, transmits all other colors.
A RED filter absorbs violet, blue and most green, transmits red and a little green.
A GREEN filter absorbs violet, blue and red, transmits green, a very little blue and some red.
A BLUE filter absorbs green and red, transmits blue and a little green.
Filters freely pass their own colors, and when used with light at the opposite end of the spectrum, have reduced transmission. Hence, at higher altitudes (or harsh clear days) shadows illuminated from the sky are bluish, and factor for yellow, orange, etc. must be increased. Conversely, when working with yellow earth (such as Death Valley) or early or late in the day (when light is warm) the exposure factor for such filters must be reduced.
The eye "sees" green as lighter than panchromatic film. Hence, the use of orthochromatic film will be better for the greens, OR the use of an X1, X2, or the "B" tri-color green. These filters will raise the values of the greens and will also lower the values of the blues and reds.
With the use of panchromatic film and filters, a good rule of thumb can be expressed as follows (this does not apply to the polarizer):
WITH FILTERS TRANSMITTING WARMER LIGHT (yellow to red):
1. DECREASE the exposure factor with early or late sunlight, or with subjects with definite "warm" color values.
2. INCREASE the exposure value at high altitudes, under clear blue skies and under overcast, and with subjects of definite "cold" color values.
WITH FILTERS TRANSMITTING COLDER LIGHT (violet, blue, and green):
1. INCREASE the exposure factor with early or late sunlight, or with subjects with definite "warm" color values.
2. DECREASE the exposure value at high altitudes, under clear blue skies and under overcast, and with subjects of definite "cold" color values.
NUMBER COLOR APPROX. FACTOR STOP +
6K1 Light Yellow 1.5x ½ stop
Purpose - Outdoors, absorbs excess blue to slightly darken sky and emphasize clouds.
8K2* Yellow 2x 1 stop
Purpose - With pan film renders mostly tonal correction and increase contrast and emphasize clouds.
9K3 Deep Yellow 3x 1-1/2 stops
Purpose - Increases overall contrast, darkens sky and emphasizes clouds slightly more than the 8K2.
11 Yellow-Green 4x 2 stops
Purpose - Improves general flesh tones, produces fair sky effects and neutral foliage.
12 "Minus Blue" 2x 1 stop
Purpose - Absorbs violet and blue to produce good sky effects.
15G Yellow-Orange 3x 1-1/2 stops
Purpose - Darkens sky, good for sand and wood.
21* Orange 4x 2 stops
Purpose - Penetrates haze, darkens water. Also recommended for mountain and aerial photography.
23A Orange-Red 4-5x 2 stops
Purpose - Darkens sky and water, emphasizes clouds, penetrates haze, darkens foliage and lightens flowers.
25A* Tri-Color 8x 3 stops
Purpose - Red With pan films, produces dramatic skies, darkens foliage, lightens flowers, penetrates haze. Slight underexposure produces moonlight effects in daylight. Use on feminine portraits if she has a bad skin tone. Best all round filter.
29F Deep Red 16x 4 stops
Purpose - Same as 25A only more extreme.
47 Deep Blue 5x 2-1/2 stops
Purpose - Lightens deep blue, darkens reds and yellows, accents fog and haze. Good for photographing light objects against the snow.
56B Light Green 6.5x 2-1/2 stops
Purpose - Produces good skin tones for men, darkens sky, lightens foliage.
58B Tri-Color Green 8x 3 stops
Purpose - Lightens foliage, darkens flowers, absorbs reds. Good for woods, meadows and gardens.
11X1* Green 4x 2 stops
Purpose - Darkens sky to the way you actually see it. For best skin tones on men. Use on women if only very flatly lit.
13X2 Green 5x 2+ stops
Purpose - Same as 11X1 only never recommended for women.
C5 Tri-Color Blue 5-6x 2-1/2
Purpose - Emphasizes fogs and mists.
80B* Blue 3x 1-1/2 stops
Purpose - Emphasizes fogs and mists to the way you actually see them.
Polarizer 2 - 2-1/2x 1+ stop
Purpose - Cuts glare and haze. Recommended for photographing water, glass, or any highly reflective material.
(*) Denotes recommended filters.