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| The pictures above show the differences between how our eyes see colors (left), and how b&w films record these colors (center). Black and White film records some colors as the same shade of gray. With use of the proper filters (right), the colors can be changed to different shades of gray, and, as in this example, making the nearly invisible, visable once again. |
The reason for using filters in black and-white photography might seem obscure. In color photography you know that filters can change the color of a picture. A color change is obvious and often dramatic. But in black and-white photography, filters change only gray tones. Since you see in color, the changing of gray tones may seem rather subtle, even superfluous. But it isn't.
Objects readily apparent in color, even boldly contrasting, sometimes teeter on the brink of invisibility when rendered in black-and-white because they can blend together in similar shades of gray. Through filtration, you can change what would have been similar shades of gray into different shades of gray. Though gray is but one word, it stretches wide. From light to medium to dark, there are roughly 200 shades of gray that your eye can discern. Achieving a contrast and gradation between those shades assumes supreme importance in making a black-and-white photograph. Show me filters for B&W films...
Most black-and-white films are sensitive to all the colors you can see. Films sensitive to a full range of colors are called panchromatic. They are the mainstay of general, everyday photography. KODAK T-MAx 100 and T-MAx 400 Professional Films are two popular panchromatic films. Much of the filtering required for black-and-white photographs results because the eye and black-and-white film respond differently to light. For instance, film is extra sensitive to blue light, showing it lighter in the final print than originally perceived by the eye, although T-MAx Films are less sensitive to blue than other pan films. Black-and-white film also responds to ultraviolet radiation, which you can't even see. The difference becomes apparent when some scenes in a photograph don't quite appear as you remembered them. For the most part, this difference is a shift in brightness caused by the film's sensitivity to blue light and ultraviolet radiation.
Correction filters occasionally come in handy when taking pictures by tungsten light. Tungsten lamps throw off an abundance of red light (most of our household lights are incandescent bulbs; the filament in household bulbs are made of tungsten, therefore the name). The excess of red light knocks the gray tones in the print slightly out of kilter with conventional films. With T-MAx films, the tonal difference is almost unnoticeable. Even with conventional films, the variance in gray tones is usually slight and probably won't displease you. If it doesn't don't fret about filtration. However, if for some reason you need to show flesh tones and other tones as they would appear in daylight, use a correction filter. For the most natural looking effect, use a No. 11 yellowish green (X0) filter with Kodak panchromatic films in tungsten light. The No. 11 filter absorbs the extra red light. Blue light and ultraviolet radiation are also absorbed, but the effect is not notice able because tungsten lamps radiate such a small amount of blue light and UV radiation.
When you want to photograph a scene not as you see it but as you imagine it, use a contrast filter. Contrast filters lighten and darken the grays in black-and-white prints. These grays correspond to the colors in the scene. When film records different colors as similar grays, a distressing merger can occur. The appropriate contrast filter can remedy the problem by darkening one gray and lightening the other.
For example, the flowers and leaves of red geraniums photograph as nearly the same tone of gray. By using a No. 25 red filter, you can lighten the geranium flowers and darken the leaves (see an example). That is appropriate since you probably think of flowers as brighter than leaves. You can produce unusual effects in your black-and-white pictures when you understand how filters influence brightness relationships. To lighten an object, choose a filter the same color as the object. To darken an object, choose a filter that absorbs the color of the subject. Some of the more common contrast filters are the No. 15 deep yellow, No. 21 orange, No. 25 red, No. 47 blue, and No. 58 green. The filters for B&W films table will help you pick the filter you want.
One of the most frequent uses of contrast filters in black-and-white photography is to darken a blue sky so that white clouds stand out. As mentioned, a No. 8 yellow filter reproduces the blue sky more as your eyes see it. However, your mind often unduly convinces your eye that those fluffy white clouds and deep blue sky have much more contrast than they actually do. Thus the sky rendition from a No. 8 yellow filter is often too light to please you. A No. 15 deep yellow filter produces a darker sky. To really emphasize the clouds and blue sky, opt for a No. 25 red or a No. 29 deep-red filter. Then the effect will be even more dramatic than you could have envisioned. These same filters can be used to darken blue water, though the effect on water is some what less than that on the sky because of reflections.
A polarizing filter provides an other method of darkening a blue sky. You obtain the maximum effect when you take pictures at right angles to the sun (for example, when your shoulder points to the sun, the sky directly in front of and behind you will be most affected). With an overhead sun, only sky near the horizon can be darkened. For spectacular effects in black and white, try using a No. 25 red filter with a polarizing filter. For more information on polarizing filters, see the Polarizer page.
Without a filter, clouds tend to merge with the sky. To make clouds stand out against a blue sky, use a No. 25 red filter. Because skyscapes readily reveal a film's grain, use an extremely fine-grained film.
The sky may appear lighter in your pictures than you would expect for these reasons:
You cannot darken an overcast sky with a contrast filter. An overcast sky has roughly equal amounts of red, green, and blue light in it, making it colorless. Its gray appearance results from the low reflectance of white light (roughly 18 percent reflectance for a medium-gray object compared with 90 percent for a white object). The only way to darken an overcast sky is with a split-field neutral density filter. A split-field neutral density filter has one half clear glass and one half gray glass. The gray glass is the neutral density filter. A neutral density filter simply reduces the amount of light without changing its color. To darken an overcast sky, align the neutral density portion of the split-field filter to the sky (you also darken every thing else covered by the filter). See the Neutral Density page for more on neutral density filters (coming soon) .
Shadows define the depth and shapes of things. In sunlit pictures of sand or snow, the perception of texture depends on the tiny shadows thrown by grains of sand or flakes of snow. These shadows show up lighter on film because they reflect the blue sky light to which the film is sensitive. A yellow filter blocks some of that blue light, darkening the shadows and stressing the texture.
The same filters that darken blue skies also lighten skin tones-it's an effect you may or may not want. In portraits with the blue sky as a back ground you can preserve the skin tones and darken the blue sky by using a No. 11 yellowish-green, a No. 15 deep yellow, or a polarizing filter. Avoid overexposing the sky, or the effect of the filter will be weakened.
If the sky is not in your picture and you just want good skin tones, you are better off without a filter. The film does a good job. However, if you are into portraiture you might want to alter skin tones for special effects or for contrast with clothes or the back ground. To give a man a more swarthy, masculine look, use a No. 56 light green or a No. 58 green filter. Since skin is reddish colored, the green filter absorbs some of the red light, darkening the skin.
For a blonde-haired person you might choose a No.15 deep yellow filter. It lightens the hair with little change of the skin tones. With a No. 25 red or a No. 29 deep-red filter you can drastically lighten skin tones. Sometimes ghoul-ish looking, the milky white tones produced by the red filter can also be haunting and ethereal. A red filter is sometimes used in fashion photography to suppress blemishes and stress shape. The lightening of the skin is usually more pronounced with light skinned people than with dark skinned people.
Haze filters cut through the haze to give clearer pictures of distant scenes. They belong in the camera bag of every traveling photographer taking black-and-white pictures. How often have you walked out on an observation deck or pulled over at a highway lookout only to find yourself admiring the haze? This is the haze syndrome. You needn't always suffer from it, although sometimes you should.
True atmospheric haze is bluish. It results from the scattering of light by atmospheric dust, water vapor, and the air itself. Haze also scatters ultraviolet radiation that you can't see but the film can. It records the scattered ultraviolet radiation giving your pictures more haze than you remembered.
Once we tell you how, your inclination will be to cut right through the haze. Nothing wrong with that-if you want to show details in the distance. However, the haze itself is a way of stressing distance. Its buildup causes subjects to increasingly pale into the distance, which cues you to their distance. For instance, tourists in mountain regions often underestimate the distance to a nearby mountain. What they guessed to be a one-hour stroll turns into an all-day trek towards a mountain that never seems to come closer. The mountain only seemed close because the clear air didn't make it appear as pale as would have the hazier air at lower altitudes. Haze buildup not only suggests distance, it also separates fore ground, midground, and back ground. Furthermore, it adds a light, airy feeling to a picture.
When confronted with haze, you have to decide whether to preserve, reduce, or increase it. To preserve the haze in the scene, shoot without a filter or with a No. 8 yellow filter. The No. 8 filter is suggested because, unfiltered, the film might increase the haze effect slightly.
To reduce the haze, use a No. 15 deep yellow or a No. 25 red filter. The No. 25 red filter gives a greater reduction of haze. Don't count on completely eliminating the appearance of haze. It usually won't happen. To increase haze, use a No. 47 blue or a No. 38 light blue filter. Since the film accentuates the haze effect any way, you might get the effect you want without using a filter. By using a filter on an already hazy day, you can nearly obscure the background.
Skylight or haze filters for color film do not penetrate haze. These filters reduce the bluishness in pictures made in the shade and on overcast days and pictures of distant scenes. A filter can't cut through fog or mist. Mist and fog are white and composed of water droplets. A filter does not affect neutral-colored objects (white, gray, black).
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