WHAT'S A CIRCULAR POLARISER?

Mike Harris explains how circular polarisers work, and shows you how to use them to add impact to your photos

There’s nothing polarising about this kit bag staple; it’s arguably the most widely used filter of all. Circular polarising filters are used to help prevent glare, cut through reflections and bolster the intensity of blue skies. They’re particularly handy when you’re shooting landscapes and architecture, but their ability to reduce glare – even the shine of a person’s skin – means they have a broad appeal.

You could write a very dense and scientific book on polarised light, but to put it simply, polarised light creates glare, which is something you can’t remove in post-production. A polarising filter blocks polarised light from a specific direction, and that’s why it reduces glare, increases contrast and boosts colour.

Circular polarisers are one type of polarising filter, and they’re available as both screw-on and slot-in filters. A common misconception is that the name refers to the shape of the filter, when it actually refers to the way polarised light is filtered in comparison to a linear polarising filter. Without getting too technical, linear polarising filters can interfere with the metering and autofocus systems of some cameras, and as such, circular polarisers are now much more commonplace in photography.