DSLR Photography: Understanding Shutter Speed

The next segment of DLSR photography that we will cover is shutter speed. If you missed it, click here to learn more about exposure and aperture.

Shutter speed is literally as it sounds, the length of time that the camera's shutter is open. Think of the shutter as a curtain inside of the camera in front of the sensor that opens and closes. The amount of time that the shutter is open determines how much light is let into the camera and how much movement can be captured in a photograph.

When you set the shutter speed, you determine how long the shutter will be open and how much light can make it to the camera's sensor. A fast shutter speed (think of the curtain opening and closing quickly) will only let in a small amount of light. A slow shutter speed (think of the curtain staying open for a longer amount of time) will allow plenty of light into the camera.

Your camera will record any movement within the frame for the entire length of time that the shutter is open. If you use a fast shutter speed you can stop action (this is useful for sport's photography or any action shots that you want to freeze in time). Conversely, a slow shutter speed will capture all movement within your frame (see image of metro train below).

Shutter speed is measured in seconds and fractions of seconds. One would think that a fraction of a second is fairly fast, but you would be surprised at how much movement can be captured with a shutter speed of 1/30.

The image below illustrates where the camera's shutter speed is displayed. You can also see what the shutter speed is through the camera's viewfinder by pushing the shutter button half way down. The larger the denominator (bottom number) of the fraction, the faster the shutter speed is.

To change your camera's shutter speed, simply put your camera in manual mode and turn your camera's front dial (pictured below). 

Keep in mind, it becomes difficult to get a crisp shot when hand holding a camera and using a slow shutter speed. In many cases, using a slow shutter speed requires the use of a tripod. If you don't have a tripod with you, leaning against or propping your camera on something stable can help to reduce camera shake. 

A good tip to reduce camera shake, is to have the denominator of your shutter speed meet or exceed the number of your focal length. For example, if you are using an 18-55mm lens and are zoomed in to 55mm, your shutter speed should be at least 1/60 if hand holding your camera. Similarly, if you are using a 100mm lens/ focal length, you should try to keep your shutter speed at or above 1/125.

The picture below is one that I took in D.C. using a slow shutter speed in order to capture the movement of the incoming train. The man in this photo was standing still. If he would have, for instance, raised his hand to itch his head - the movement of his arm would be captured in this photo due to the fairly long shutter speed used.

As we discussed in last week's post about aperture, there is a semi-manual mode for shutter speed as well, called shutter priority mode. Shutter priority mode is TV on Canon and S on Nikon. Shutter priority mode allows you to set your shutter speed and ISO and the camera will compensate by setting the aperture automatically, to get a properly exposed image.

If you have time this week, try working with a moving subject (i.e. people, an animal, vehicles, running water etc.). Change up your shutter speed and take some time to look at what impact this has on your photographs.

Please feel free to leave a comment with any questions that you have or anything that you would like for me to cover in a future post.