See through a glass darkly with a neutral density filter kit. We put the best to the test

Neutral density filters are enormously versatile, enabling you to easily create effects that are difficult or impossible to produce in editing apps. Two-stop and three-stop filters are popular for giving the option of using wide apertures under bright lighting conditions, so you can gain a tight depth of field without suffering overexposure due to the limitations of your camera’s fastest shutter speed. ND filters can be even more advantageous when shooting video.

Six-stop and ten-stop filters go further still, giving the possibility of long exposures even on a bright, sunny day. For example, where an aperture of around f/16 at ISO 100 gives you a shutter speed of 1/30th of a second, a six-stop filter slows the exposure to two seconds, and a ten-stop filter gives you an even longer 30-second exposure.

A favourite use of high-power ND filters is to give a milky smoothness to the appearance of flowing water, from waterfalls and weirs to rapids. They’re equally adept at smoothing the choppy surface of rivers, lakes and the sea, as well as enabling clouds to appear to streak serenely across the sky. You can even use them to blur pedestrians out of bustling city street scenes.

One option is to use a ‘variable’ or ‘fader’ ND filter. These are based on two polarising elements. Twisting the filter’s adjustment ring rotates one element in relation to the other, enabling a progressively denser effect. Typically, you can expect a density range of around one to eight stops. However, image quality can be second-rate, and there’s no beating a top-notch ND filter for consistent, reliable performance. Here we’ll take a look at what four leading kits have to offer.