Why a Polariser is the One Filter You Need

What’s the best filter to have in your photographic arsenal? Award-winning landscape & wildlife photographer Drew Buckley gives us his opinion.


Why a Polariser is the One Filter You Need

Use side lighting and a Polariser at 90 degrees to the sun for maximum effect to deepen blue skies and seas. All images by Drew Buckley


There’s nothing quite like our love affair with accessories. After you’ve bought anything these days, you always need something extra to go with it to make the experience more special.

The same can be said for cameras. There’s a whole array of cables, add-ons and bits and bobs to fill your kit bag up with. Filters, however, would be in my opinion the must-have landscape items to own, up there after camera and lens. They are at first tricky to get your head around, and implementing them at the right time is a skill in itself, however their proper use can pay dividends. If there’s just one filter to buy, in my opinion it’s the polarising filter.

Why? Well, the effects of a polariser filter cannot be replicated in post-processing. Unlike how exposure blending can replace graduated ND filters, or a long exposure can be faked by stacking shots, the effects of a polariser have to be implemented at the time of the shot.

The effect a polariser has depends on the angle of the light striking a subject. For boosting the blues of the sky, they work best at right angles (90 degrees) to the sun, and as such are less effective when the sun is behind the camera. They also work great on waterfalls and in overcast conditions, reducing surface glare and reflections from water and foliage.


Why a Polariser is the One Filter You Need

A serene afternoon at Broad Haven beach in Pembrokeshire, with a polariser turned 90 degrees


The nitty-gritty – how polarisers work


Polarising filters work by blocking certain light waves entering the lens. Visible light from the sun travels in a straight line in a wave that’s oscillating in all directions, side to side and up and down. When that light is reflected off an object, it’s the reflected wavelength of the light that determines the colour of that object. The rest of the colours are absorbed by the object.

So for example, green leaves on a tree only reflect the green light, and absorb the other remaining colours of the spectrum (you all know the rhyme!). Likewise for a pure blue coloured object, it will only reflect the blue light hitting it. If the light being reflected or scattered travels in just the one direction, it will cause glaring and reduce the colour intensity of the reflected surface. So by using a special filter to remove this polarised light; the colour intensity remains true.


Why a Polariser is the One Filter You Need

Polarisers work great on your coastal scenes making sea colours pop


It sounds complicated, but it’s easier to understand when seen in practice. If you simply rotate polarising filter while it’s attached to the front of your lens you can see the effect happening through the viewfinder. This is thanks to the filter containing a layer of Polaroid, which is synthetic plastic sandwiched between two planes of glass. As the filter is rotated, the angle of polarisation and the amount of polarised light that passes through the filter both change. This will allow you to precisely control the degree of polarised light that is to be removed.

The first benefit you’ll notice from this is that your blue skies will become a much deeper blue and clouds will really stand out. This is because the sky contains a lot of scattered light, so just isolating the light rays can cause a massive visual impact for any scene. Polarising filters can also cut down the glare from non-metallic surfaces such as foliage. This will increase the colour saturation of your foreground details, ultimately enhancing your images. You’ll also be able to see through water and glass, because the filter eliminates reflections.


Why a Polariser is the One Filter You Need

Polariser off


Why a Polariser is the One Filter You Need

Same camera settings, with polariser turned 90 degrees. Notice how the foliage and water reflections are immediately removed, revealing the true colours and making for a more vivid scene


Which type?


Why a Polariser is the One Filter You Need

Hoya 77mm HD Digital High Transparency Circular Polariser Filter


There are two types of polarising filter available: linear and circular. Linear filters were made years ago to work with older film cameras and SLRs, and if like most people these days you’re wanting to use a polarising filter with your DSLR or CSC, you will need a circular version (shortened to CPL). They both do the same job, it’s just mainly down to the fact that circular polarisers are manufactured differently in order to make sure your digital camera can still measure exposure, focusing and metering readings correctly through them. Circular doesn’t refer to the physical shape of the filter, more how it’s used.

Circular polarising filters are available in either slot-in or screw-in variations – most of the time you’ll find the screw-in type. These attach by screwing the filter onto the end of your lens, so you’ll need to check your lens’ filter thread size (measured in millimetres) to make sure you purchase the correct one. These are the best option as they’re fast and easy to use.

You can also purchase slot-in circular polarising filters, such as the LEE 100x100mm CPL, which work by slotting in to the filter holder.

Lastly there are versions of polarisers that attach onto the outside of a filter holder with an adapter ring. These are the best to use if you’re planning on using neutral density filters and/or graduated neutral density filters at the same time.


Why a Polariser is the One Filter You Need

Polariser off


Why a Polariser is the One Filter You Need

Straight out of camera, same settings, polariser rotated 90 degrees, cutting through mist and haze and revealing correct colours of the landscape and sky


Due to the nature of how polariser filters work they will inevitably reduce light intake slightly, so be prepared to lose one or two stops of light when calculating your exposure times. This can work to your advantage in some situations though – when shooting waterfalls you’ll not only be cutting reflections on water and foliage but also extending your exposure time to create appealing blurry water effects.

As a final point, do avoid using polarisers on super wide angle photos as it can introduce vignetting and on clear blue skies, as you’ll more than likely end up with an ugly dark circular area at 90 degrees to the sun. Zooming in slightly can combat this.


Click here to shop for polarising filters


About the Author


Drew Buckley


Drew Buckley is a multi-award winning landscape and wildlife photographer based in Pembrokeshire, Wales. He's authored many books and runs his own photography workshops in Pembrokeshire and on Skomer Island in the summer months. Check out the availability calendar on his website to book a workshop. Visit his websitefind him on Facebook, and follow him on Twitter.


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