Tiffen black and white filters

Black and white imaging records only tonal differences between colored objects, which appear as black, white, or different shades of gray.Proper rendition depends on your own desires, and, for film, the differences between film sensitivity to colors and that of the eye.The latter is due to the fact that most panchromatic emulsions used are more sensitive to blue, violet and ultraviolet than to other colors. Therefore, blue appears as lighter on film than it does to the eye. This can make a blue sky light enough to appear a similar shade of light gray as the clouds that are in it, making the clouds "disappear." A more "correct" cloud presence is obtained through the use of a yellow filter, such as a Wratten #8, which can absorb blue light, darkening the sky to more closely match what the eye would see. The #8 also acts as a general compensator for most subjects, giving a tonal rendition similar to that of the eye. Deeper colors, further to the red end of the spectrum, such as Wratten #15 deep yellow, #16 orange, and #25 and #29 red filters will produce progressively deeper and artificially more dramatic renditions of blue sky.

Remember that, since these filters act on color differences to produce tonal differences, the required colors must be present.The part of the sky you are recording must be blue to be affected. Sky sections closer to the sun, or nearer the horizon, are generally less blue than elsewhere.Use of a gradated neutral density filter can darken a sky relative to the foreground, but will not increase contrast between a blue sky and the clouds. In most situations where color-contrast and tone adjustment is involved, these filters work similarly for black-and-white video as for film.

Using filters for contrast control can be a matter of artistic preference, or of necessity. It is possible for two disparate colors, say a certain orange and blue, to record as the identical tone, eliminating any visible difference between them. Filters will lighten objects of their own color and darken those of their complement.Complementary color pairs are: green-red; orange-blue; violet-yellow. An orange filter in the above case will darken the blue, and lighten the orange; a blue filter will perform the reverse.

A green filter, such as Wratten #11 , can be used to lighten green foliage, to show more detail. It may also be used to provide more pleasing skin tones outdoors, especially against blue sky.

Any filter used for the above purposes will have a greater effect if slightly underexposed. Its function depends on absorbing light of its complementary colors to increase the proportion of light of colors similar to itself. Exposure compensation is often needed to allow proper image density, but the relative difference is reduced by the addition of light at the absorbed wavelengths through additional exposure.

Yellow 12 : "Minus blue" cuts haze in aerial work; reduces excess blue of full moon in astrophotography. Recommended as a basic filter for use with Kodak Aero Ektachrome Infrared film.

Orange 21: Absorbs blue and blue greens. Renders blue tones darker as in marine scenes.

Red 23A: Light red filter producing contrast effects that darken sky and water, as in more dramatic architectural photography. Not recommended for flesh tones.

Blue 47: Dark blue filter that accentuates haze and fog. Used for dye transfer and contrast effects.