As most camera owners know, the camera shutter’s primary job is to control the amount of light passing through in order to ensure the correct exposure of the photo being taken. It opens for a pre-chosen amount of time to allow just the right amount of light from the scene to pass through the camera onto the sensor and record the image. We can set the amount of ‘shutter open’ time recommended by the camera for any given scene, or ignore its recommendation and choose our own shutter speed, or we can just let the camera do it all automatically. If the shutter is open for a brief instant, such as a five hundredth of a second, we call that a fast shutter speed or short exposure. If it’s open for much longer, such as a quarter of a second or longer, it’s called a slow shutter speed or long exposure.
That’s straightforward enough, but what’s more interesting, is how the length of time that the shutter is open affects the way movement is recorded on the final image. If anything in the scene moves while the shutter is open, it will be blurred in the image unless the shutter is open for the tinest fraction of a second, or if the movement in the scene is so slow that it’s unnoticeable. Not all blurring is bad, though. We can obtain some interesting effects by keeping the shutter open and capturing the blurring effect of moving subjects contrasted against the sharpness of a static background. This kind of photography is often called time lapse photography.
Fast and slow shutter speeds
Look at the two shots above of the same fountain taken at different shutter speeds. The first is taken at one 750th of a second. The individual droplets can be seen shooting out of the fountain as can their individual splashes on the water. In the 2nd photo – on the right, the shutter is open for a whole second. The individual droplets all appear to smear into each other, and all the splashes as they hit the water tranform into a kind of sheen on the water’s surface. Notice also the traffic in the background. In the fast shutter speed shot, the traffic has been stopped in its tracks. In the slow shutter speed shot, the traffic that is moving is just a blur while the stationary traffic is sharp. The moving traffic is blurred because it managed to cross the whole image frame while the shutter was open. Both are valid approaches to taking the shot. It all depends on the ‘look’ that you prefer for that particular scene.
Note that with shutter speeds of less than around one thirtieth of a second, you can’t hold the camera steady enough, so you need to use a tripod or at least have the camera held firmly against a hard surface. Camera shake causes blurring of the whole scene and ruins the shot. If you use zoom, then camera shake is even more noticeable if you try to hold the camera by hand when taking a picture with a slow shutter speed.
In the shot below of Loch Lomond at night, (scanned from 35mm film) the shutter was open for 30 seconds as it was almost pitch dark. The slow shutter speed enabled the little amount of sky light available to build up enough to record the image. During that time, the waters of the loch kept moving and splashing around, so, in the image, they merge and form a misty effect on the surface. Notice that the tree stump, unlike the water, doesn’t reflect any light so it appears as a silhouette rising from the misty-looking loch. I had considered using flash to illuminate the tree stump a little and reveal some of its texture, but I think the featureless black silhouette is more atmospheric.
Loch Lomond – slow shutter speed
Here’s another use of a long, slow shutter speed during an approaching thunderstorm. In the lightning shot below, the shutter was left open for around 8 seconds, during which time a lighting strike obligingly provided its own bright but brief illumination. Because of the slow shutter speed, some city lights are over-exposing, but there’s no visible movement so there’s no blurring. The main subject is the lightning and the clouds, so it doesn’t matter about the city lights being over exposed. Obviously there were quite a few failed shots before the lightning decided to make an appearance for this shot.
Lightning strike with slow shutter speed
To explore the shutter-controlled effects shown in this article, there’s no need to dive in at the deep end and go fully manual if your camera has a ‘shutter priority’ setting. The ‘shutter priority’ setting means that you select the shutter speed you want, and the camera will attempt to adjust all the other exposure controls to ensure the exposure setting is still correct. The main thing is just to try many shots and see what effects you can achieve. Take note of what works and what doesn’t, and refine your technique accordingly.
This article is aimed at the majority of compact camera owners who simply set their camera permanently on auto and just ‘point and shoot’ every time they take a photo. If that’s you but you want to delve deeper into the different types of effects that are possible, it’s time to explore the camera’s many settings other than ‘full auto’.