Photography News | Issue 68 | photographynews.co.uk
Technique 16
Essential guide to… Filters Words and pictures by Will Cheung
There’s something satisfying about getting stuck in to the camera. See overleaf for some brands to consider. Here, we focus onwhich filters no photographer should be without
The polariser
If you buy only one filter, make it the polariser. This unassuming plain grey filter can achieve effects not possible in software. The vast majority of modern cameras need a circular polariser. This is not a reference to the filter’s physical shape, but to the way the filter’s crystals are laid out. So a circular polariser can, in fact, be square. The other polariser type, linear (which can be circular or square in shape, too), is relatively rare now anyway. In the right situation (and this is important) a polariser can intensify colour, kill reflections off water and glass, cut down glare and saturate blue skies. It’s also handy as a weak neutral density. But it can also have no effect at all. It all depends on the light and situation. On cloudy days, there is not much polarised light around, so the polariser hasn’t got much to work with. On bright days, however, sunlight strikes a surface and bounces off in all directions, ie it is polarised. Now if you use the polariser, most of that light scatter is cut out, so you get better saturation and no glare. With reflective surfaces such as glass and water, shoot straight on and there is no effect. Move so you
are positioned around 45° to the surface, rotate the polariser and you will see reflections are minimised. Formore on the science of this, check out ‘Brewster’s angle’ on theweb. If you are new to polarisers, the best thing is to learn when a polariser works and when it doesn’t. In different situations, even whenyouare not intending to take a shot, just hold it up to your eye and rotate it and see if there is any effect on the scene. Most polarisers come in a mount that allows the filter to It is screwed into the adapter ring, then the filter holder itself attached. Above The polariser is then rotated using the holder’s drive wheel and extra filters can be then added in front Right This is the Marumi magnetic filter polariser in place.
be rotated while on the lens and it is important to adjust the filter and shoot when the effect is at its best – this might not be when the effect is at its strongest. There are also polarisers that come in a fixed frame and can be rotated via another mechanism,
like the drive wheel used by the Marumi system. Finally, here are three user tips. First, only fit the polariser when it has a genuine benefit. Don’t leave it on the lens constantly, because the near 2EV light loss can mean blurred shots due to slower shutter
speeds. Second, with ultra-wide lenses, blue skies can look patchy, so watch out for this. Third, in some strongly lit situations, a perfectly good blue sky can look almost unnaturally black. All in all, though, a polariser is very much a good thing.
With polariser
No polariser
Above Enhanced skies and minimised glare can be achieved with a polariser. Here, a Marumi polariser was used. The non-polarised shot was exposed at 1/320sec at f/9, while 1/100sec at f/9 was needed for the polarised image. Look closely and you can see that the window reflections (particularly those far right) have been cut down in the polarised image
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