Getting the best from a polariser By Justin Minns As a landscape photographer filters are an essential part of my kit. Neutral density (ND) filters allow me to control the shutter speed for creative effects such as blurring water or clouds, while graduated ND filters are invaluable for balancing the light in unevenly lit scenes, when the dynamic range would otherwise exceed that of the camera. Top of the list though is the very useful but often underrated polariser which deserves a place in every landscape photographers bag. Using a polariser So what exactly does a polariser do? Without getting into the science too much, light becomes polarised when it bounces off a flat non-metallic surface, such as water or foliage as well as off moisture and pollution in the atmosphere. This polarised light is what causes reflected glare or haze which can reduce the intensity of colours in an image. A polariser simply filters out these unwanted reflections, the result is bluer skies, greener leaves, reduced or eliminated reflections, and greater clarity in the final image.
Polarising filters need to be rotated to change the angle of light that is filtered out, the effect can clearly be seen through the viewfinder so it’s just a matter of rotating the filter until the desired effect is achieved. The intensity of the effect can be controlled by changing the angle of the camera, the strongest effect coming with the camera at an angle of 90 degrees to the sun. Linear v circular There are actually two types of polarising filter: linear and circular. These terms refer to the way that the filter modifies the light waves that pass through it rather than the shape of the filter.
Linear Polarisers only allow light waves moving in one linear direction to pass through, something which can cause problems for modern camera’s metering and auto focus systems. With a circular polariser the light enters the lens in a circular pattern and this is the one to use with digital cameras.
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NEWSLETTER MARCH 2019 / VOL. 4 / NO. 2
