Photo filters

There is a school of thought in photography that holds that any photograph should be identical to the scene actually perceived at the time it was photographed and, due to this, filters should not be used. I personally disagree with this. To begin with, we all in effect do use filters when we choose different films (every film has different colour reproduction characteristics), when we change white balance settings on our cameras, or when we make certain adjustments in photo editorial software. More importantly, though, what really matters is whether a photograph you took makes an impact. If you took a photograph that is identical to the original scenery but does not move anyone, would anyone pay attention to it? I seriously doubt it. At the same time, if you took a picture of a boring scene which was improved by using a filter to the extent that everyone stops and says "Wow", would anyone care about the fact that you used a filter? Again, I seriously doubt it. Photography is an art - and any art is about expressing perception as opposed to duplicating reality.

That said, though, no filter can remedy bad lighting conditions. Nothing beats the naturally perfect light. Although some people are big on filters, I personally prefer to spend my time finding a great scene and corresponding light to make a great photograph without using filters as opposed to choosing a fancy filter in an attempt to make a good looking picture out of a dull scene.

Many traditional filters have become redundant with the introduction of digital photography and digital darkroom techniques. If you shoot digital, you can use white balance settings to correct colour reproduction. And if you use digital darkroom (for either scanned film or original digital images), Adobe Photoshop or any other photo editorial software gives you much more flexibility and precision to correct colour rendition and/or contrast. For example, a correction achieved by using warming-up filters (81A, B or C) is easily done in Photoshop, which actually allows for a far greater degree of correction precision. As another example, the effect achieved by using a graduated neutral density filter to reduce contrast in a scene can easily be accomplished by taking two shots of the same scene (one exposed for the highlights and one for the shadows) and then combining them in Photoshop.

Nevertheless, I do not think that filters will ever be entirely abandoned. First, it is always better to improve photographs at the point when they are taken as this allows for more space for post-processing (or, in other words, fewer manipulations in photo editorial software result in smaller degree of colour posterization and banding). Second, there are several things that no post-processing can change, improve or simulate. To just mention a couple, you can not use Photoshop to remove reflections in the same way a polarizer does or make water look milky if you used a fast shutter speed at the point of shooting.

Due to the above reasons, as of now I use the following filters:

UV Filters (I use Nikon L37c)

I use it mostly for protective purposes. Every one of my lenses has a UV filter permanently attached to it and I take them off only when taking critical shots or using other filters. It is much easier to buy a new filter than replace the front element of a lens! Talking about protection, having a lens hood on also helps a great deal.

Warming Filters (I use B+W 81A)

This filter is used to reduce the blue cast and warm a scene up. I use it when I shoot film only.

The pictures above were taken with Fuji Provia 100F slide film. The photos on the left were taken without any filters and show a quite heavy blue cast. The photos on the right were taken with an 81A filter and the blue cast is visibly reduced.

As with any filter, the real question is when/if it should be used. While the photograph in the second raw certainly benefited from using the filter, I am not sure that the same holds for the picture in the first raw - I tend to think that the first photo expresses the stormy mood better by adding a bit of coldness into the scene.

Polarizing Filters (I use B+W MRC Slim Circular Polarizer)

There are two kinds of polarizing filters - circular and linear. This has nothing to do with their physical shape - the difference is whether they can be used with cameras that employ auto-focus and matrix metering without affecting these functions. Buy a circular polarizer if you use a modern auto-focus body.

A polarizer might be neutral in colour or coloured. The former is supposed to not alter colour balance (not all polarizing filters are perfect here, though), while the latter adds a cast of the same colour the filter is.

This filter can be used in the following ways:

• Manage reflections (from water, foliage, etc.).

• Darken the blue sky - the most know application of a polarizer. This application is not the most desirable, though, as if you use the filter with modern slide films the sky usually gets unnaturally dark or even almost black and everyone can see that it was "polarized".

• Increase contrast and/or colour saturation.

• As a neutral density filter.

Neutral Density Filters (I use B+W 102)

These filters simply reduce amount of light that reaches the lens and is used to increase exposure time. This may be very useful when you want to obtain a slower shutter speed to make running water look milky or if you want moving objects to appear blurry (e.g. foreground flowers waving in the wind or walking people). Another important application is to increase exposure time to obtain minimum flash sync speed when using a fill-in flash in bright daylight.

I personally find that 4-stop ND filters are most useful. In bright daylight and at ISO100, even a 3 stop ND filter is not enough to bring the shutter speed to 1/2 seconds even at f/22.

Graduated Neutral Density (ND) Filters

These filters are used to decrease contrast in a scene.

Things to keep in mind

• As you will read elsewhere, you only need to buy one set of filters of the size that corresponds to the filter size of your biggest lens and then use step-up rings to use them with smaller lenses.

• I strongly recommend avoiding using two filters at the same time whenever possible. One good quality filter (multicoated and made of glass) will not degrade image quality visibly; however, if you use two or even more plastic filters, image quality is bound to suffer.

• Be careful when you use a polarizer with ultra-wide-angle lenses as polarizing effect may vary significantly across the scene.

• I find square filters (e.g. Cokin systems) a real pain in the neck to use. You have to take UV filter off, screw in a ring which supports filter holder, put filter holder onto it, then take out a filter and put it in (dismounting, of course, takes the same number of steps). With screw-in filters, you simply take your UV filter off and put the filter you want to use on. In real practice this is a huge difference! Due to this, the only type of square filters I use is graduated ND filters as they require the ability to move the filter in place to precisely position gradation division line.