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Garry Black Photography |
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Tips and Techniques |
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FILTERS |
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The following has been excerpted from A Guide to Photographing the CANADIAN LANDSCAPE, by Daryl Benson and Dale Wilson. For further information on this publication, please feel free to contact us.Filters are to photography what adjectives are to writing. They add colour, flavour and an individual style to what is being communicated. Filters for colour photography fall into several categories, depending on their intended use. Types include Neutral-Density and Colour Graduated Filters, Colour Compensating, Correcting and Enhancing Filters, Polarizing Filters and Soft-Focus Filters. Although all of these filters were designed for specific purposes and applications, they need not be limited to those circumstances-in fact, au contraire! Graduated Filters Our eyes can easily see all the detail in a scene with light-level differences in excess of ten f-stops. In comparison, film has, at best, an exposure tolerance of two to three stops from the brightest to darkest scene areas (that's for slide film; print film has a stop or two more latitude but still nowhere near what the human eye can see). That lack of exposure latitude in film is the second reason many photographs don't turn out the way we remember the scene. When shooting around the 'golden' hours of light at sunrise and sunset we're often faced with a range of light intensity of at least five stops from the brightest areas (the region of sky where the sun is), to the darkest areas (usually the foreground). We have three choices in this situation. We can overexpose the sky to preserve foreground detail, we can silhouette the foreground and expose the sky properly, or we can call in the cavalry: use a graduated filter to help get an exposure with detail in both foreground and sky. Physically, all useful graduated filters are rectangular with a clear bottom half and, starting near their horizontal middle, a gradual application of neutral or coloured material that increases in density up to the top (see illustration). The neutral or coloured material absorbs one, two, three or more stops of light, according to its specification. By using a graduated filter over your lens and positioning the edge of the neutral density portion on the horizon you can hold back light from the sky while allowing foreground light to reach the film unhindered. This reduces the range of light between sky and foreground to something the film can handle. Graduated filters should be one of the landscape photographer's first filter purchases. We suggest you start with the Cokin 'P ' series filter holder. Most filter manufacturers have adopted it as a standard of sorts and they offer filters to fit it. If you use a medium or large-format camera, however, you might consider the larger Cokin 'X-Pro' or 'LEE' holders and systems (see 'Resources and References' pages ? and ?).Colour Compensating, Correcting and Enhancing Filters There's a whole hockey sock full of specialty filters that will correct, alter, or compensate for various different light sources or printing situations. However, in the world of creative photography we're more interested in using such filters to inject mood or to exercise creative license. Blue/Cooling Filters There are two main categories of blue filters: the 80 series, which are colour-conversion filters to be used when shooting daylight film with tungsten light sources, and the 82 series, also used to balance the colour temperatures of warmer light sources. We've never used them for that. Our favourite 80-series filter is the 80A, dark blue with a 2-stop filter factor. Whether you realize it or not, you've seen the results of this filter: it has long been used to create what is known as 'Hollywood Midnight.' The 80A is great at mimicking the blue hues typical of night scenes and when the shot is underexposed by about one stop the effect is very much as if it had been made by the light of a midnight full moon. The next time you see Lorne Greene ride over the horizon on a tranquil night, remember the scene was probably filmed at high noon. Another situation that can make one instinctively reach for the 80A is a scene full of pristine fluffy white snow. Although warming filters are often recommended to counter the blue bias prevalent with snow, if the scene wants to be blue, make it blue! Try a diffusion filter as well, and overexpose up to two full stops. You'll have so much success with this combination in winter that you're likely to find your unfiltered shots boring. Another aspect of colour filters is the psychological effect they have on our emotions; for example, blue can evoke strong feelings of serenity or coolness. Filters can be used to reinforce and enhance such moods in a photograph. Warming Filters Most warming filters are intended to correct the excess blue of a heavily overcast sky or open shade, or to allow the use of tungsten-balanced film in daylight. The 81 series of light-balancing filters are all, to varying degrees, light yellow. The 81B is the model to start with: it is strong enough to create a sense of warmth, but it doesn't completely overpower the cooler colours that may be in the scene. The 85 series filters are a strong amber or orange and are designed to convert tungsten-balanced film for use in daylight. Again we seldom use them for that purpose, but we do use the strong orange 85 to dramatically enhance those hues at sunrise and sunset. Colour Enhancing and Intensifying Filters Several styles of this filter are available to enhance or intensify almost all of the colours in your photographs-all at once. Each manufacturer has a different version with a slightly different effect on film. Howard Ross's Enhancing Filter (the original) has the strongest effect, and because of this it's one of our favourites. It enhances almost all colours: reds, oranges, greens, blues and violets. The only colour it doesn 't help out is yellow. Because of its strong enhancing effect it leaves a noticeable magenta colour bias in the more neutral hues or tones (the whites and greys). Singh-Ray produces a Colour Intensifying filter that does not leave as heavy a footprint on the image: it's subtler to the colours it enhances and is kinder to the neutral hues and tones. Tiffen, Lee and Cokin (see 'Resources and References') also make colour-enhancing filters whose effect is most noticeable in the warmer hues, the reds, oranges and browns.Another set of filters that must be mentioned are the fluorescent-correcting FLW, FLD and FLB models. They all have a pinkish/magenta hue and are designed to eliminate the greenish colour that fluorescent tubes and mercury-vapor street lights cast on daylight film. Because these filters are magenta in colour they are great for use at dusk or dawn to exaggerate and enhance similar hues in a sky shot, a landscape or in the Northern Lights! Polarizing Filters Regardless of the type of shooting you do, a polarizer is the most useful and versatile filter you can own. It's a very visual filter to work with: as you rotate it in its mount the effects are immediately noticeable. A polarizing filter can deepen the colour and contrast in a sky (the most intense effects are always 90 from the light source), eliminate glare from wet or reflective surfaces and cut through atmospheric haze to increase clarity and contrast in a scene. A polarizing filter will increase exposure times about two to two-and-a-half stops, and so it can be used as a moderate-strength neutral-density filter. Such a filter is useful when you want to show motion blur or the passage of time; a long exposure of a silky cascading waterfall is a classic example. Polarizers come in two varieties, 'linear' and 'circular. ' Each has the same effect visually; the difference is just in the way they polarize the light passing through. If you own an auto-focusing or auto-exposure camera (basically any modern camera), use a circular polarizer, which won't interfere with its automatic functions.Cokin has an amazing series of colour polarizers that selectively add colour to a scene, rather than just reducing glare as a standard polarizer does. The colour combinations these filters come in are blue/yellow, purple/orange, red/green and red/blue. We've tried them all, and in our opinion the star of the series is definitely the model 173 blue/yellow.Soft Focus Filters It seems ironic that as film and camera manufacturers produce sharper and crisper products, photographers are leaning toward softer, more diffused looks in their images. Romantic, painterly, pastel, moody, soft, muted, dreamlike, foggy, atmospheric, ethereal and glowing; these are all terms commonly used to describe the look of diffused images. But there are more varieties of soft focus filters than there are adjectives describing them. Here are some tips for using soft-focus filters. The larger the aperture the more pronounced the diffusion effect will be. Long focal length lenses require less diffusion than short ones to achieve the same visual effect. Landscape images are usually best with strong diffusion, while portraits are better with a more subtle effect. Bracket your exposures: diffusion filters often collect light from outside the image area that can mislead the camera meter and cause it to underexpose. Conclusion All the filters we 've talked about cost money, some quite a lot of money. Neither of us suggests you go out and immediately purchase an arsenal of filters. We suggest a basic starter kit that includes, in order of importance and versatility: 1) a regular circular polarizer, 2) a Cokin #173 blue/yellow colour polarizer, 3) a 2-stop, neutral, soft-edge graduated filter, 4) a 1-stop, neutral, soft-edge, graduated filter and 5) a warming filter (81B). |
