Polarizing Filters for Landscapes
Essential Tools for Improved Photographs
A polarizing filter can be an invaluable tool for the landscape photographer, provided it is used correctly.
A polarizing filter can transform outdoor pictures from disappointments to deeply satisfying shots, and has a place in every landscape photographer’s camera bag. But they won’t always have the effect you expect and they won’t always improve the picture, so it is worth learning how to use them.
The Circular Polarizing FilterA polarizing filter cuts out or reduces certain elements of the light as it enters the camera, which can greatly enhance the image. But the effect depends on the angle of the sun in relation to the subject. The effect is greatest on pictures taken at right angles to the sun, and is reduced or negligible when the sun is directly behind the camera.
The most common type of polarizing filter is circular. The holder screws onto the front of an SLR camera lens and you will need to rotate the filter within its holder to strengthen or reduce its polarizing effects. The “correct” rotation will vary from shot to shot so you will need to adjust it each time you change the direction of the camera.
Polarizing filters can have three effects:
Increased Vibrancy
They can produce more vibrant colours, resulting in shots that are more dramatic and “punchy,” and therefore more pleasing.
The increased vibrancy affects all the elements of the landscape, but is often most noticeable in the sky and can turn pale, insipid blues into rich shades of azure. The same effect increases the level of contrast, so within the deep blue sky the clouds tend to be better defined.
The vibrancy effect of polarizing filters can dramatically improve pictures, as the two attached shots of a river estuary show. These shots were taken a few moments apart, with the sun at 90 degrees to the camera direction.
Reduced Reflection and Glare
Polarizing filters can also reduce reflection and glare from water and other surfaces, although this effect depends on the vertical angle of the shot as well as the angle of the sun.
The two shots of a rock pool show how the polarizer reduces reflections near the camera, but the effect fades as the angle changes towards the top of the picture.
Slower Shutter Speeds
Like neutral density filters, polarizers tend to reduce the amount of light that passes through the lens, therefore reducing shutter speeds.
This effect can be useful in shots of moving water, to increase the blurred appearance of breaking waves or a flowing river. But shooting at shutter speeds slow enough to introduce motion blur means you will need a tripod, which is always a good idea for landscape shots.
It is possible to reproduce some effects of the polarizing lens with software after the shoot. But relying on miracles from Photoshop is never a good strategy, and in any case at the processing stage it is too late to get rid of any unwanted glare or reflections.
The Downside of Polarizing Filters
On wide-angle lenses, of 28mm or less, the thickness of the glass of less expensive polarizing filters can severely reduce the amount of light at the corners of the shot, causing unacceptably severe vignetting. Zooming in to a slightly less wide angled shot will fix the problem, otherwise the solution is to crop the darkened corners during processing or get a thinner, more expensive filter.
And beware of overdoing the vibrancy effect. Polarizers can make an already deep blue sky appear almost black, which might not be the effect you want.
As always, the best way to understand polarizing filters and learn to use them effectively is to experiment. Try similar shots with and without the filter, in different lighting conditions and at varying angles to the sun and reflective surfaces. Make sure you know which shots were filtered and which not; and take a close look at the results.
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