|Changing the shutter speed can help you blur backgrounds.
An exposure is the time from when a camera starts taking a picture to when it stops and this length of time is variable and determined by 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. With some cameras you can also press the shutter button and until you take your finger off, the camera will continue to expose. This is called a Bulb setting.
By adjusting the shutter speed you can control how the subject appears in the picture. A fast shutter speed will freeze the subject and a slow shutter speed will make it look blurred as the subject moves.
There are several images you can produce, the first is following the subject as it moves, pressing the shutter button as you pan. If you get it right the subject will appear sharp as it hasn't moved position in the viewfinder, but the background will be blurred making the subject look as though it's moving at speed.
Landscape photographers could try using a slow shutter speed on a waterfall - gushing water will turn into a silk-like flow of water. Go for a fast shutter speed and it will turn almost icy with splashes caught frozen in mid air.
You can also select a fast shutter speed 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. Using a subject-freezing shutter speed is perfect for capturing a goal-scoring footballer in his tracks but is less effective for cars or vehicles as it makes them look static.
Most digital cameras have different exposure modes which change how much control you have over the shutter speed.
If you pick automatic mode, when you press the shutter button halfway, the camera will judge how much available light there is and pick the settings accordingly. If you pick Program, the camera will control the shutter speed but let you change some other settings. Cameras also have scene modes which are pre-programmed and can be used to photograph a particular scene or subject such as, portraits and sport. When using a scene mode, you can't control the shutter speeds.
Manual mode gives you complete control over the shutter speed and aperture while Semi-automatic modes will either let you have control over the shutter speed or aperture (aperture-priority mode and shutter-priority mode). You can only set the shutter speed when in manual or shutter-priority mode, the rest of the time it's left to the camera.
Shutter speed also works in harmony with the aperture – if your aperture is wide open you can use a faster shutter and the image will take less time to expose as more light is let into the camera. This relationship is very useful for when you're photographing in the dark. Because there's less light, exposures would usually be longer but if you use a wider aperture to let more light in and flash, you can use a faster shutter speed so you wont be standing around, waiting for the camera to finish the exposure for as long. A higher ISO (something we'll cover later) will also help with this. Remember, if you're using a wide aperture your photograph will have a shallow depth of field which may not be appropriate for the scene you're photographing.
We hope you enjoyed and learned a few things with this article from the ePHOTOzine Academy Series. This is just one part of a 13 part series - to view others follow the links below: