Shutter

SHUTTER

A camera shutter controls both the exact instant when the film is exposed to light and the duration of that exposure. The shutter is used in conjunction with the aperture and ISO to control the exposure. The most important function of the shutter is that it limits the time that light is allowed to pass through the lens and act on the sensor.

Shutter speed is the length of time a camera shutter is open to expose the camera sensor to light. Shutter speeds are typically measured in fractions of a second, when they are under a second. Slow shutter speeds allow more light into the camera sensor and are used for low-light and night photography, while fast shutter speeds help to freeze motion. Examples of shutter speeds: 1/15 (1/15th of a second), 1/30, 1/60, 1/125.

A shutter speed of 1/100 second will let in twice as much light as a shutter speed of 1/200 second but only half as much light as a shutter speed of 1/50 second.

Using a fast shutter speed will help prevent blurring of the image due to camera or subject movement. In the case of the following image of an Egret in flight not only was the bird moving, but the camera was also moving. A fast shutter speed of 1/1600 sec. was used to freeze the movement.

Using a slow shutter speed can result in a blurred image due to camera shake or can be used in conjunction with a tripod to deliberately blur movement. Using a slow shutter speed of 1/2 sec or longer can be used to blur the water in a waterfall as shown below. A tripod must be used when doing long exposures.

You will learn more about Shutter Speeds in the Camera Controls section of this Photography 101 Course.