Photography News Issue 30

Photography News Issue 30 absolutephoto.com

Technique

during the exposure will appear as a blur, and the amount of blur depends on two things; the speed of the subject and the length of time the shutter is open; therefore, assuming its rate of movement is constant, a subject will take on twice as much motion blur at 2secs as it does at 1sec. We’ll come on to what speeds are required for different effects later. So, if you know you want a long exposure, how do you generate a slow shutter speed? That depends on the exposure mode you’re using. For instance, in shutter-priority (T or Tv) or manual mode (M), you can simply dial in the speed you want up a maximum of 30 seconds and the aperture will close to compensate (up to a point). Alternatively, in aperture-priority you can set a very small aperturewhichwill naturally force the shutter speed to lengthen. The best mode to shoot in for long exposures, however, is bulb (B). This mode lets you keep the shutter open for as long as you like using a lockable remote release. In T (time) mode one press opens the shutter and another closes it. Lower and slower Having decided the speed youwant, youmight find you can’t use it without overexposing and this is common when working in shutter- priority, manual or bulb mode. It happens because the shutter speed you want to use is letting in more light than can be compensated for by the aperture setting; it simply can’t be closedany further to create agoodexposure. To deal with it, first try setting the lowest possible ISO setting to reduce the camera’s sensitivity to light. If the camera is still overexposing at your chosen settings, you’ll need to use a faster shutter speed, wait until the available light has fallen or use a filter. Stop the light Filters; this is where the real technical art of long exposures begins, because armed with the right ones you can shoot with speeds of many seconds or minutes, no matter how strong the light in the scene. The filters you need are neutral density (ND) types and long exposure (LE) filters, and while they do the same job – essentially, cutting the amount of light entering the camera by a given amount – there is a difference. ND filters are supposed

1 second

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Above Here, you can see the effect of various shutter speeds on the water around Thurlstone Rock, Devon, and the length of exposure should be driven by the look you want to create. If some texture in the water is required, giving a more natural look, then a speed of around 30 seconds is fine. But for a more mist-like finish, the exposure needs to run into the minutes.

to keep colours neutral, while long-exposure filters, which cut out much more light, usually make no such claims, often warming or cooling colours. These colour casts can be corrected in Raw processing, or rather than use auto white-balance set a manual value. You can stack two ND or LE filters to multiply the effect, or combine regular NDs with graduated versions so highlight areas like the sky are better exposed. Watch out for vignetting when stacking screw-in filters. Using more than filter also has possible implications for image quality and the greater chance of flare. For more on picking an ND filter, and the strength you need see the panel. If you’re using a variable ND or LE filter, take care. These work fine most of the time, and even allow you to focus while they’re attached, by setting the filter to a low strength, then turning it back ‘up’ after locking the focus. However, don’t turn the bezel on the filter too far or results can be patchy, causing some areas to be under or overexposed. You’ll also find that shooting at very wide angles produces problems in terms of the coverage, the same way that polarising filters do (it’s on these that variable NDs are based). Moving scenes So what sort of scenes and subjects work well with long exposures? It’s no surprise that they’re used a lot in coastal photography, where there’s an ever-shifting mass of water

to blur, and in fact any moving water can look good when it’s recorded over a period of many seconds, rather than a fraction of one. However, the most important thing is simply to ask whether the scene looks better with or without blur, and if so, how much is required? Taking the sea as an example, there’s no right or wrong way to shoot it, only that which fulfils your motives. So, if you conceive of a peaceful, relaxing scene, a long exposure is a good route, where the texture of the water softens allowing the static elements to come to the fore. Other areas where motion blur can be useful is in shooting long grass and trees, where the latter will appear to shiver as they move in the wind. Or where busy, cluttered skies are drawing attention from a landscape or piece of architecture. The same goes for people in city scenes, because with the right amount of shutter speed you can turn them into a sinuous trail or remove them entirely to make busy streets into a ghost town. How slow should you go? Deciding on the length of exposure to use is muchmore important than finding subjects to blur; the former shows photographic intent, while the latter is just an excuse for a technical exercise – sure, learning to shoot long exposures can be a thrillingly eye-opening experience, but once you’ve done it, ultimately you’ll realise it’s just a means to an end.

Viewfinder covered

Viewfinder uncovered

Above When using long exposure filters to allow slow shutter speeds, it’s important to shield the eye piece, both to avoid overexposure and to stop internal reflections off the filter. Here light leaks could have spoiled a 30secs exposure of Seljalandsfoss, Iceland.