Super Test: Filter Systems

Getting things right ‘in-camera’ can be a real time-saver. Matthew Richards puts a selection of popular square slot-in filter systems to the test

Eight square slot-in filter ND grad sets tested side-by-side in our exhaustive Super Test

Wide-ranging enhancements available in image-editing programs enable you to bring out the hidden beauty of your shots, but it can be a labourintensive and long-winded process. There’s a valid argument that says it’s better to capture images that are closest to how you want them while you’re actually shooting. That’s often impossible unless you use a filter, or even a combination of filters.

Let’s take an early-morning landscape shot as an example. The sky is likely to be vastly brighter than the land beneath. You could expose for the sky, in which case the land is likely to look dark and murky, or you can expose for the land and the sky will be washed out, and may even turn into a vast expanse of blown highlights.

The answer is to use an ND Grad (graduated neutral density) filter, which is clear at the bottom, graduating to light, mid or dark grey at the top. This will balance the overall exposure. If a river runs through the scene, you could also use an additional plain neutral density filter, to facilitate a long exposure that will smooth troubled waters with motion blur.

There are also effects that you can create with filters that are simply impossible at the editing

stage. For example, circular polarizer filters can cut reflections in water, glass and other reflective surfaces.

A major choice is whether to go for round or square filters. Round filters screw directly to the front of the lens, so they’re a good choice for clear or UV filters that you might use for permanent protection. But they have their limitations. Stacking two or three filters together for a complex creative effect can give rise to extreme vignetting. They can also work out very expensive if you need to buy different sizes to attach to different lenses, unless you resort to buying them to fit your largest lens and use additional step-up rings.

It’s hip to be square

For landscape photographers as well as for those that like to use a range of different filters, the square filter approach is a much more viable option. In this case, you’ll probably only need to buy one filter holder, plus a set of relatively cheap adaptor rings to suit your various lenses. The filters themselves are typically simple sheets of resin or glass that slot into the holder. You’re therefore not paying extra for an aluminium circular frame with a threaded attachment mechanism with each filter, as you do for round filters. Not all square filters are square. Many are actually rectangular, and this is especially true of graduated filters. A big bonus of these, compared with round graduated screw-in filters, is that you can raise or lower the filter within the holder, so that the crossover region lines up with the horizon. With a round graduated filter, you’d be forced into composing shots with the horizon running through the centre of the frame.

Square filter system come in a variety of sizes. The size is usually quoted as the width of the filter, the most popular being 67mm, 85mm and 100mm. Naturally, you can buy individual filters to create the effects that you want. You can also mix and match holders and filters from different manufacturers. To compare typical prices, however, we’ll be looking at complete ND Grad kits that include three filters of different strengths, plus an additional holder and adaptor ring, where not included. We’ll also be quoting the prices of individual components.

A bonus with square filters is that you can raise or lower the filter within the holder, so the crossover region lines up with the horizon