A complete guide to photographic filters
By Shelton Muller
In our changing photographic arena, what filters should we buy?
There are few photographers who don’t use filters to some degree. But the use of filters continues to be a subject of controversy. Are they tools used by photographers to cheat — rendering images that are not possible in the real world? Or are they tools that assist photographers in their creation of an image that exemplifies what they feel, rather than simply what they are looking at? And thus the controversy rages. Despite all this fuss, photographers also use filters to correct or enhance photographs when technological limitations are placed upon them. Even the most ardent purist nature photographers like Galen Rowell will use certain filters to overcome limitations of film and metering.
As with all extremes, too many filters – or the wrong ones – can actually hinder the photographer and destroy the image. Photographers need to understand that in essence, the quality of the image is entirely reliant upon them. Effect filters will rarely make eye-popping images of poor compositions or pictures where the photographer invests little of him/herself. That is why the choice of filter is particularly important both at the time of purchase and in those crucial moments when they can either make or break a good image.
There are many filter brands, types and systems and rarely will a photographer work exclusively with only one. Brands like B+W, Hoya, Arrow, Fotar and Marumi all make screw-in type filters that have a metal rim and are made from optical glass. Brands like Cokin, Lee and Singh Ray are essentially filter systems that require adaptors fitted to the lens. The filters are placed into tight slots in these adaptors. Naturally, there are advantages and disadvantages to each and so interplay between systems and filters often occurs.
Ultraviolet and Skylight filters are usually par for the course. You will find them tightly screwed on to most lenses these days. While they do little to actually enhance the image, they are optical quality front element protectors and they will save you from scratching, grinding and denting your front lens element. For this reason alone, they are a worthwhile investment. There are many filters, however, which do not fall into the class of everyday usefulness and worthwhile investment. Filter companies produce brochures that display spectacular photographs taken with all sorts of special effect type filters that you may use once or twice and then never use again. These may cost you upwards of $70 and when you are starting out with filters, this money could be better spent. There are many other filters, though, that have greater usefulness in a greater variety of circumstances. Let’s look at these.
Polarisers
One of the most oft-employed filters is the polariser. Every photographer should have one. When light is reflected from a surface it travels in a single plane, unlike normal daylight which vibrates in all directions. Polarising filters cut through this kind of light and thus remove unwanted reflections. At first, its usefulness may appear somewhat limited. However, to the landscape or travel photographer its benefits cannot be stressed enough.
Polarising filters can be used to remove highlights reflected from certain surfaces such as foliage and even the ocean. Such reflections weaken colour, and so a Polariser removes the glare and intensifies the hues. As these reflections are removed, the colours appear as they would be seen without the disadvantage of polarised light. Oceans become blue-green and inviting, while landscapes become more colourful, the details sharpened. Sky is partly polarised and a Polariser will often deepen the blue, especially at right angles to the sun, where the light is most polarised.
Polarising filters are most successful when the lens axis is about 60 degrees to the reflecting surface. But don’t try them on chrome or other shiny metals, as they will have no effect whatsoever.
Cokin makes a Polariser that has become very popular in the United States. Known as the Cokin 173 Blue Yellow Polariser, it actually overcomes the “cold blue” tendency inherent in some Polarisers, which benefits landscape photographers, who prefer warmer tones in their images. The 173 Polariser (or “warming polariser” as it is affectionately known) accomplishes this while simultaneously deepening the blue in sky and ocean, producing some knockout colours in these scenes. But a word of caution: the Cokin 173 Polariser is in reality an “effect” filter and its effect can be overdone. As with all filters, use with discretion.
Graduating filters
Graduating filters have a colour or tone which graduates gently about halfway through the filter and deepens as they reach the top. Graduated filters come in all sorts of colours and can be used to enhance sunsets and to add colour to otherwise bland and empty skies.
The most useful graduated filter is a graduated grey or neutral density filter, as it can be used to maintain detail in overexposed areas – without making any distinct colour change. By so doing, the photographer can expose for foreground (which may require one or two stops more light) and still maintain detail in the sky or distant hills.
These kinds of filters are rarely found in screw-in type mounts. While there are half-half type filters available, there is no graduation in the colour and a harsher line is visible. The advantage with slot-type filter systems is that the filter can be moved up and down in the adaptor to accommodate the photograph and its composition. Your best bet here is Cokin. While other slot-type filter systems exist, they are difficult to come by in Australia and are much more expensive.
Warming filters
Warming filters come in different strengths and are otherwise known as 81A, B, C and EF, according to strength. As their name suggests, warming filters are particularly useful for enhancing skin tones in portraits or for counteracting the cold, blue light of flash or the winter outdoors.
Its appeal is purely psychological as humans are naturally attracted to warmth over cold. An 81 or “warming” filter can add this quality to your photographs, but again, discretion is required. One of the most effective uses for this kind of filter is during those times when the light it attempts to replicate is actually present – namely morning and afternoon.
The long shadows subconsciously indicate the time of day and the filter enhances the quality of the light. The discretion required here is twofold. First of all, if the warmth is too strong, your photograph can look contrived. If it is used in the wrong photograph it can negate its use altogether. For portraits, minimum strength is required. You would not want to use anything more than an 81B. Any greater warmth would certainly “cook” the subject and it would appear as if he or she had spent the last year under a sunlamp.
Diffusing filters
Diffusing filters are most often used in portrait and wedding photography. They evoke a sense of softness and romance and are excellent for reducing sharpness in a portrait. Diffusing filters and for this reason are very effectively used in “glamour” work.
A diffusing filter should never unsharpen your image, however. If it does, it is not a quality filter and should not be used. When buying a diffusing filter, check first that it retains the sharpness of the image and only “blows out” the highlights. You can test this very easily by holding it up to your eye and looking through.
Filters and digital
With the growth in popularity and quality of digital capture, certain filters may become less essential to the photographer. Among these would be the diffusing filter, as photographers often prefer to shoot sharp and diffuse on a computer, thus retaining both options – sharp and soft. Likewise, the effect of warming filters can be created using PhotoShop and other photo editing software. Digital cameras often have a white balance setting, so correction filters for tungsten and fluorescent light can also be unnecessary.
You cannot, however, replace a Polariser. Nor can the balancing effect of a graduated filter be effectively achieved on a computer. CCDs have similar limitations to film and graduated filters are still necessary to help overcome them. Much really depends too on the photographer’s philosophy, and this applies to both kinds of capture – digital and traditional. All kinds of effects can be used in photography. Filters are among them. Effects can be applied in the capture, or in the darkroom – be that digital or traditional. If, when and how you wish to apply these effects is up to you.
Photography is an art. It is not simply about capturing an image. It’s about creating one. In this regard, the words of writer Henry David Thoreau ring true: “The question is not what you look at, but what you see.” Filters are tools that can help you create exactly that.
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