Playing with time

Shelton Muller discusses the creative and logistical reasons for selecting your shutter speed.

Whereas the aperture in your lens controls the amount of light you allow for you exposure, your shutter controls the amount of time you allow it to flow. The photographs you take will be affected by the shutter speeds you choose in some rather obvious ways.

The faster the shutter speed, the more frozen in time the moving elements will appear in each picture. The slower the speed, the more blurred they will appear, and for differing reasons. Perhaps the most wonderful aspect of understanding shutter speeds is the apotheosis of playing with time.

Einstein and Asimov

Playing with shutter speeds is an almost deifying experience. The ability to play with time in an image is the ability to reveal everyday events that the human eye cannot see, but are nonetheless known to our subconscious. It’s the stuff of Einstein and Asimov.

Slower shutter speeds are not recommended for hand -holding because even the most staid or sedate photograph will suffer from blur caused by camera movement. Every time you press your shutter release button your camera moves slightly, unless firmly mounted on a tripod. More on this later. Nevertheless, longer exposures can be both a creative and logistical advantage to the photographer, either for recording movement effects the human eye only perceives but doesn’t actually see – or for allowing more detail to be captured on film or by the camera’s digital sensor. This is especially true at dusk or nightfall when a tripod mounted SLR can capture the movement of cars in a cityscape or the swirling of stars as the earth moves beneath them over a period of hours. Where moving objects are seen in relation to stable, non-moving objects the perception of time is conveyed very effectively. Try doing this with people in a scene, rides at a fairground, waves over rocks. There are many opportunities for this kind of photograph.

 The reverse is true of course with faster shutter speeds – that is to say shutter speeds of say 1/1000^th of a second or faster. Moving objects are frozen in time in a way not seen by the human eye. Sporting and athletic events, birds in flight, water in motion and many other things can be captured in an interesting way using very fast shutter speeds.

Focal Length and Shutter Speed

As we have briefly mentioned, slower shutter speeds are not recommended unless the camera is placed firmly on a tripod. But how slow is slow? Well, all things are relative, and much actually depends on the focal length of your lens. Lenses of longer focal length not only magnify the scene, but also the blurring effect of camera shake in a picture. Consider this. If your lens magnifies 6 times, it will similarly exacerbate camera shake by the same factor. Telephoto lenses are also less stable to hold than lenses that protrude less from the camera body, so it stands to reason that the longer the lens, the faster your shutter speed should be. A rule of thumb to consider is to match your shutter speed with the focal length of your lens. For instance, if you are using a zoom lens at 200mm, select a shutter speed of around 1/250^th or faster. If you are shooting with a digital SLR, you may actually select something a little faster again due to the fact that the size of your camera’s sensor may further increase the magnification of the lens.

This is not to say that if you are using a 12mm lens that you can hand hold effectively at 1/12^th of a second! Really, anything below 1/60^th or thereabouts would probably need some sort of support. This is a general rule of thumb and you may find yourself able to hold your camera at even slower speeds than the recommended by this rule.

Shutter Speed and Direction of Movement.

Shutter speed should also be regulated by the nature of the movement of the subject, as to whether it is travelling across the shutter plane, at a 45 degree angle away or toward it, or directly toward or away from the camera. If your intention is to freeze your subject, remember that objects moving across the plane of the shutter require much faster shutter speeds than those moving directly toward or away from the camera or at angles to it. In fact, whereas a shutter speed of 1/1000^th may only be required for an object travelling directly away or toward the camera, a shutter speed of 1/4000^th of a second may be required for the same object travelling at the same speed if it is travelling across the shutter plane. Consider this when selecting your shutter speeds for motor racing and similar sports. Your placement in relation to the subject will bear heavily upon your choice of shutter speed.

However, movement is usually better implied when motion blur is included. An image of a Formula One racing vehicle frozen on the track is nowhere near as interesting or descriptive as one in which it is obviously doing what it is renowned for – travelling quickly. In this case, a slower speed might be the preference combined with a panning camera motion as it passes. This will keep the subject sharp enough while simultaneously blurring the background. This applies of course to all moving subjects, and the option to play with your shutter speeds is one you should explore.

Shutter Speeds and Flash

Combining the lightning fast time of your flash with the variable rate of time of your camera’s shutter is a fabulous plaything. While your camera will no doubt have a preferred synchronisation speed, it must be remembered that this is the fastest speed your camera will allow for synchronisation with the flash. It doesn’t mean you can’t use slower ones, does it? So, anything slower than your synchronisation speed is entirely your playground.

So, by cleverly combining flash exposure with ambient light, you can do a few important and creative things. Firstly, you can give your indoor flash photography a more natural look, while simultaneously illuminating your subject adequately. This you would do by using a shutter speed that matches the ambient exposure of your scene, while throwing in a little flash for good measure. This technique can be a lifesaver in room scenes in which people need to be seen in a context. Large rooms are difficult to illuminate with your on-camera flash of course, but are usually artificially lit. Use the light you are given along with a hint of flash on the people who may perhaps be in the foreground. The exposure may be relatively long, so tell your subjects to be as still as possible while you take the picture.

You can also combine the suggestion of both motion blur and sharpness simultaneously in an image. Rear curtain flash synchronisation is a technique long used to create this visual idea. Many camera/flash combinations allow you to do this and it is not difficult to master. By setting your camera to fire the flash at the end of the exposure instead of at the beginning, your subjects will be both blurred by their own movement during the exposure, and then frozen by the flash at the end. This is done on some cameras by setting the flash setting to ‘Rear” or “Slow”. A little bit of experimentation is needed because each situation is different. However, your shutter speed should be slow enough to capture both the movement of your subject and enough ambient light for detail and context. However, enough exposure should also be allowed for the motion freezing effect of the flash. It can be a fine balance sometimes.

 Understanding the effect of time – short or long – on your images is really the key to creatively utilising your shutter. So, far more than simply an exposure mechanism, your camera’s shutter is your doorway to a world in which time can be altered in single frame.

Shelton Muller is a Melbourne –based professional photographer and the editor of  Total Image and Better Pictures magazines. For further information, Shelton can be contacted at shelton@total-image.com.au.

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