Camera Shutter Speeds explained

Having a little knowledge about how the camera's shutter speed works can help you obtain pictures with more impact.
Words & Pictures Peter Bargh

Photography derives from the words writing with light and a photo depends upon exposure of a light sensitive material. In a traditional cameras case the light sensitive material is film or in the latest digital cameras its a charge coupled device or CCD. The amount of light reaching the film or CCD is known as the exposure and this is controlled by two items on a camera - the aperture and shutter speed. The aperture is a variable hole in front of the lens that adjusts to let more or less light through and the shutter speed is a cover over the film or CCD that controls the length of time that the light reaches the film.

As well as their practical needs both can be used creatively in photography and in this technique we will take a more detailed look at shutter speeds. The shutter speeds of cameras can go from long exposures of 30 or more seconds to fast speeds of anything as short as 1/8000sec.

All cameras from the most basic point-and-shoot single use camera to the latest highly sophisticated digital SLRs have shutter speeds. The very basic compact models may have a fixed speed and theres nothing you can do with these. More advanced 35mm compact cameras have adjustable shutter speeds, but the speed is controlled automatically and you have no override. And then we go into the more sophisticated cameras such as the digital cameras and SLRs. With this type of camera you still have the automated control but also an override of some form to allow more creative use of the shutter speed. And its here where we can start to have fun.

By adjusting the shutter speed you can control the movement of the subject. A fast shutter speed will freeze the subject and a slow shutter speed will make it look blurred as the subject moves. You can also combine flash with a slow speed to get movement and blur all in the same shot. Lets look at the techniques one by one.

If you have no control over automatic exposure you can do a couple of things to help obtain a slow shutter speed. One is to use the slowest film you can find. In print film this is ISO100 but you can safely override the speed to ISO25 to fool the camera into increasing the exposure by two stops. If you dont have film speed override you can buy stickers to put over the cassette before you load it. Slide film is available in speeds down to ISO50. Again you can override this and set ISO25, but you must tell the lab to adjust processing to compensate.

Anther alternative is to place a neutral density filter over the lens. This is a grey filter that reduces the light value and doesnt affect the colour of the picture. You can buy them in 2x, 4x, 8x and 64x values.

Another method of creating movement is to keep the camera at a fixed point and press the shutter button using a slow shutter speed. This time the subject will be blurred as it passes across the viewfinder and the background will be sharp. This takes a lot of skill to get the detail right as the subject can often look too blurred resulting in a photograph with no impact. The third technique is same as our previous example, but used to remove the subject. Its employed by architectural photographers who want to photograph a building without people getting in the way. If the shutter speed is slow theyll record as a blurred and distracting object, but if its extremely long the blurred person walking across the path of the view will be so blurred it wont even be recognisable and wont affect the picture.

Landscape photographers could try using a slow shutter speed on a waterfall. That gushing water will turn into a lava-like flow of fluid (above right). Go for a fast shutter speed and it will turn almost icy with splash caught frozen in mid air (above left). A slow shutter speed, used to make the waterfall deliberately blurred, has is more aesthetically pleasing.

A long shutter speed can be set at night to record car headlights as trails. Choose a position on a suitable bridge over a busy road and tripod mount the camera. Then fire the shutter with a speed of between one and 15 seconds depending on the length of streak you require.

Fast shutter speed in daylight The alternative of selecting a slow shutter speed is to go for a fast shutter speed to do the exact opposite to stop your subject in its tracks. In this case you need to use a shutter speed faster than the speed of the moving subject, which varies depending on the direction too. If the subject is moving across the path at close range it will appear to be moving faster than a distant subject and a faster speed will be needed. And if its coming towards you, duck! Using a subject freezing shutter speed is perfect if you want to stop a goal-scoring footballer in is tracks, freeze an athlete in mid air or an insect or bird in mid flight. Its less effective for cars or vehicles as it makes them look static.

Occasionally a static shot of a speeding car works, especially if its throwing up a cloud of dust as it hurtles around a corner!

Using flash to freeze the movement
Flash provides a burst of light in a split second that will freeze even the fastest subject in its tracks. Science and research photographers use this to study movement, by photographing subjects such as bullets penetrating their target and nature and medical photographers to study anatomical changes maybe a horses gallop, athletes jump or hummingbirds wing motion.

Using flash with a slow shutter speed Slow sync flash as its known uses flash to freeze the subject as above, but the slow shutter speed continues to record the ambient conditions and further subject movement. Its used mostly be sports photographers recording cycling events or motor sports but can also be creative in any environment that has a moving subject in the foreground.

Another example of panning with the subject this time using flash as the swinging motion creates an arc shape to pan along.

Slow shutter speed with a zoom lens
Another great technique, known as a zoom burst, will work with cameras where the zoom can be adjusted manually while the exposure is taking place.
You need to mount the camera on a tripod and set the zoom to either the short or long end of the focal length range. Then, with the camera on a slow shutter speed fire the shutter release and rotate the zoom barrel so it moves from one end of the focal length range to the other during the exposure. A steady uniform rotation is necessary to ensure a smooth zoom burst.
Most digital cameras dont have this option, but a similar effect using Photoshop Elements or a similar image-editing program can be created on a computer.

Adjusting the zoom lens as you make an exposure of a colourful flower bed creates a burst of colour.