What Is Shutter Speed?

What Is Shutter Speed?

Shutter speed is the length of time the camera's sensor is exposed to light. It is measured in seconds or fractions of a second. A shutter speed of 1 1000 means the sensor is exposed for one thousandth of a second. A shutter speed of 2 seconds means the sensor is exposed for two full seconds. Together with aperture and ISO, shutter speed is one of the three settings that control exposure, but it has its own creative effect on the image.

Fast shutter speeds freeze motion. If you want to capture a bird in flight, a runner crossing the finish line, or a droplet of water splashing, you need a fast shutter speed. The exact speed depends on how fast the subject is moving and how close it is to the camera. A person walking might be frozen at 1 250, while a racing car might need 1 4000. The faster the shutter, the less light reaches the sensor, so you need a wider aperture or higher ISO to compensate.

Slow shutter speeds create motion blur. Blur is not always a mistake. A waterfall photographed at a slow shutter speed becomes a smooth, silky flow of water. Car taillights at night turn into streaks of red light across the image. Intentional motion blur adds a sense of movement and energy that a perfectly frozen image cannot convey. The key is using a tripod to keep the camera absolutely still while the moving parts of the scene blur.

There is a general rule for handholding a camera: your shutter speed should be at least 1 divided by your focal length. If you are using a 50mm lens, you need at least 1 50 to avoid visible camera shake. With a 200mm lens, you need at least 1 200. This is because longer lenses magnify camera movement just like they magnify the subject. Image stabilization in modern lenses and cameras can give you two to five stops of leeway, allowing slower handheld shutter speeds.

Shutter speed also affects how moving objects appear in video. In video, the standard shutter speed is twice the frame rate, known as the 180-degree rule. For 24fps video, use 1 48 or 1 50. For 60fps video, use 1 120. This gives a natural amount of motion blur that looks cinematic. Faster shutter speeds in video create a staccato, jittery look similar to Saving Private Ryan, while slower shutter speeds create excessive blur.