Photography News Issue 42

Photography News | Issue 42 | absolutephoto.com Technique 99 Camera School PART 7 Here we lift the lid on all things camera related, showing how to get better results from your CSC or DSLR, and providing all the info you don’t find in the manual. So, stick with us and you’ll soon be wielding your camera like an expert. This month, how the shutter speed you choose affects movement in your shot...

Words & pictures by Kingsley Singleton

Shutter speed is one of the three fundamental components of exposure, alongside aperture and ISO. Like those settings, it has primary and secondary effects. The primary effect of shutter speed is, in concert with the aperture, to allow the correct amount of light to reach the sensor and provide a good exposure. But, again like aperture, it’s the secondary effects of shutter speed that are of more interest to creative photographers. How shutter speed works Shutter speed controls the amount of light recorded by revealing the camera’s sensor for a given amount of time. This time is either decided by you, or by the camera in response to other exposure settings. For instance in shutter-priority mode (S or Tv), you set the time that youwant to expose the sensor for and the camera will open or close the aperture to compensate for this. But in aperture-priority (A or Av) you set the aperture, and the shutter speed responds, increasing or decreasing speed to create a good exposure. What shutter speeds can I use? Depending on the model of camera and exposure mode, you’ll be able to open the shutter for a very brief period (fractions of a second), or a very long time (minutes). Most DSLRs and CSCs offer a range of 30secs to 1/4000sec or 1/8000sec, but thanks to new models with electronic shutters, this top speed can be even faster, up to 1/32,000sec. There’ll also be a bulbmode allowing you to keep the shutter open manually for any length of time you need, and this will be accessed by a B on the mode dial, or found beyond the slowest speed in the shutter speed range.

1/30sec shutter speed

1/1000sec shutter speed

How shutter speed affects moving subjects Because of how the sensor is exposed by the opening and closing shutter, what you’re recording isn’t just the amount of light in the scene, but anymovement or change in the light that’s visible during that time. So, if something is moving while the shutter is open it’ll either be recorded as blurred or sharp depending on the shutter speed and the speed of the subject. For instance, if you point your camera at the sea, and shoot one image at 1/125sec and one at 1/2sec, you’ll notice lots of motion blur from the slower shutter speed, but the waves will be kept relatively sharp from the faster one. The extra movement is recorded because the waves have had more time to travel across the frame. But it’s not only subjects that are moving in the scene which will be recorded as blur by

slower shutter speeds. If you’re hand holding the camera, instead of using it on a tripod, you’ll also find that movement in your position or the camera is recorded. This could be small movements or vibrations that you don’t even notice (camera shake), or a deliberate panning of the camera; either will be record as blur if the shutter speed is slow enough. What shutter speed to do I need? The shutter speed you need is entirely down to how you want the subject to look – sharp or blurred. Very fast shutter speeds can freeze even fast-moving subjects like a tennis ball in flight, and very slow shutter speeds can blur even slow-moving subjects like swaying branches, or shadows cast by the sun. However, in the majority of cases, when shooting hand held – as you would be for

NEXTMONTH Find out why you can’t always get the shutter speeds you want, how to overcome that problem, and how to get more creative with shutter speed, using the fastest and slowest settings. When it comes to combating camera shake, image stabilisation in the lens or camera body will offset the worst of this, but in general you should try to shoot with a shutter speed close to or above the focal length you’re using, ie. 1/60sec with a 55mm lens. portraits, or general photography – the fastest shutter speed available will give you the best results (if focused correctly, pictures will be sharp and free from motion blur). The exact speed you need to get a sharp shot once again depends on how steady you can hold the camera and how fast the subject is moving. Shutter speed, focal length and camera shake And there’s another factor to take into account; the focal length of lens you’re using. Essentially it’s easier to get a sharp shot with a wide-angle than it is when using a telephoto lens. The wider the field-of-view, the less movement will be recorded per pixel, so if you’re shooting at 18mmand 1/15sec youmight not see any blur, but if you zoom the lens into 55mm with the same speed, comparatively more movement will be visible, both from the subject and from you. no right or wrong setting. You should just pick a shutter speed that’s suits your intentions. On the left a 1/30sec speed it used for a panning effect, while on the right a 1/1000sec speed allows a sharp image. Above Fast shutter speeds freeze movement and slow ones blur it, but there’s

1/60sec shutter speed

1/4sec shutter speed

4secs shutter speed

Above Find a subject with a consistent rate of movement, like this waterfall, and shoot it at different shutter speeds. As the speed lengthens you’ll notice that the look of the moving water changes from sharp to blurred, due to the amount time it’s moving through the frame.

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