long exposure photography tips

Daytime long exposure: photography tips for smoothing water and blurring skies

Daytime long exposure photography is the landscape cliche that just won’t quit. Love them or loathe them, long-exposure landscape shots are here to stay, and judging by the amount of slow-motion seascapes in particular that are emailed to us each week, it’s clear that many of you love creating them as much as we do.

Whether it’s milk-smooth seas or cloud-smeared skies, leaving your camera’s shutter open for anything from several seconds to a couple of minutes, and allowing the world to pass by in a blur, is an addictive technique with potentially awesome results.

The time of day has a big impact on the look of your pictures, not just in terms of the quality of the light but also its quantity, and shooting at dawn or dusk near the coast enables you to capture lots of colour and detail in the soft light while using long exposures to blur the movement of waves.

You’ll need to use low ISOs and fairly narrow apertures in order to get shutter speeds that are slow enough to soften the motion of waves and clouds.

However, if conditions are too bright this may not be possible without the use of a neutral density, or ND, filter.

Not to be confused with an ‘ND grad’ (although one of those can be useful too – more on that later), a standard ND filter is simply a piece of dark grey glass or resin that’s placed in front of the lens to restrict the amount of light entering it, enabling you to use a slower shutter speed without ending up with overexposed shots. ND filters are available in a range of strengths or densities, which are measured in stops.

Each stop halves the amount of light, and the darker the filter, the stronger the effect. If, for instance, your DSLR suggested a shutter speed of 1/80 sec for a scene, attaching a 3-stop ND filter would enable you to reduce the shutter speed to 1/10 sec.

The ND effect
In this before and after example, you can see how a fairly dull scene can take on a more mysterious quality with the addition of a neutral density filter. Although the unfiltered shot is perfectly acceptable, the overcast, early morning light leaves it lacking a little ‘oomph’.

The ND filter extends the exposure from 1/8 sec to more than two minutes, smoothing out the waves and creating an effect akin to a sheet of ice.

As well as looking very cool, this creates contrast that helps to separate the rocks from the water. The filtered shot also shows the typical side-effects of using a strong ND: a colour cast (cool in this case), and slight vignetting on the wide-angle lens used here; both of these effects can be fixed in software.

Choosing an ND filter
In addition to various strengths of ND filter, there are also two different formats: screw-in or square slot-in.

The screw-in type have the advantage of enabling you to use a lens hood as normal, so you can shield the filter from the sun and the effects of glare and flare; the downside is that they take longer to fit to and remove from the lens, which can be frustrating when you want to try different strengths of filter.

Square filters are quicker to use once you’ve added the filter holder to the lens, and they also make it easier to add ND grads to balance the exposure in a picture.

Unless you opt for the additional expense of a compatible lens hood for the system you’re using, though, there’s a danger of light hitting the filter when you shoot towards the sun.