A Bit Of A Blur?

Adam Waring shows you how to use a variable neutral density filter to slow down shots just enough to convey a sense of movement

- Adam Waring

Windmills are among the most picturesque man-made structures to be found on the landscape. These once functional buildings are now mostly relics of a bygone era, but that’s not the case with Wilton Windmill in the Pewsey Vale of Wiltshire, which has been lovingly restored and preserved and still uses the power of the wind to grind grain into flour in an age-old manner. So how can we capture an image that conveys the motion of those magnificent sails?

Just as we use ND filters to shoot long exposures that turn a churning sea into a milky blur, or moving clouds into painterly streaks, we can use them to blur moving elements in a scene to capture that movement. In this case, rather than exposures that are several seconds, or minutes, long, we want one that’s typically just under a second – just enough to add a hint of blur to the spinning sails.

You need to strike a careful balance to get the right effect: if your exposure is too short it’ll just look like the sails are out of focus, rather than moving, but too long and they’ll become an indistinguishable mess – or even disappear altogether. This is where a variable ND comes in handy: as we have complete control over just how dark the filter is, we can control our exposure time precisely.