Basic knowledge → Shutter Speed and S-Mode
Shutter Speed and S-Mode
The shutter speed is the length of time that the shutter in front of the image sensor is open. While the shutter is open, the image sensor is exposed to light, from which the image is created.
The above pictures show the shutter part of the E-mount camera. The shutter is open in , and the image sensor is exposed to light. The longer the shutter speed is, the more light reaches the image sensor. For example, if the shutter speed is changed from 1/60 sec to 1/30 sec, the amount of light is doubled.
Along with the aperture, which adjusts the amount of light coming from the lens, the shutter speed is one of the factors to determine exposure.
In the auto shooting modes, P-mode, and A-mode, the camera determines the shutter speed automatically. In the S-mode, you can set the shutter speed as you like.
Effect of the shutter speed on a photograph
You can control photographic expression by changing the shutter speed. The following photographs show how they look different depending on the shutter speed.
These shots of the waterfalls were taken while changing the shutter speed.
Photograph  was taken at 1/1250 sec, the fastest shutter speed among the three. Because the length of time the shutter was open was short, it captured a moment in which the motion of water looks stopped.
Photograph  was taken at 1/20 sec. Because the water flowed while the shutter was open, the photograph looks more dynamic.
Photograph  was taken at 1/4 sec, the slowest shutter speed. Opening the shutter for a long time resulted in silky rendering of water flow.
In this way, you can enjoy various renderings of a moving subject by changing the shutter speed. You can set the shutter speed the how you want in the S-mode and M-mode, but the range of the available speeds varies by model.
If you want to take a shot freezing the motion of a moving subject, such as when shooting sports, using the fastest available shutter speed is recommended, so that you can prevent an image blur caused by the fast motion of the subject.
By shooting at 1/4000 sec, the above photograph captured the moment when the subject was trying to receive the ball. Conversely, if you want to shoot a flow of water or trails of light, using a slower shutter speed is recommended.
By setting the shutter speed to 5 sec, the above photograph captured the trails of fireworks. However, the slower the shutter speed gets, the more easily the image gets blurred. When shooting in low-light situations such as fireworks and night views, where the shutter speed tends to slow down automatically, it is essential to use a tripod to keep the camera steady.
In a scene where you cannot use a tripod, you can use higher shutter speeds by increasing the ISO sensitivity. However, note that the higher ISO sensitivity tends to cause noise on the image. Also, to shoot night views while holding the camera in your hands, the Hand-held Twilight mode in Scene Selection is effective.
Because the above photograph was shot with a slow shutter speed, the image is blurred as a result of camera shake. If you shoot a moving subject, take care to avoid blur, which can be caused by the movement of the subject, in addition to camera shake. If either the subject or the camera is moving, the image gets blurred and results in an unclear photograph.
The S-mode (Shutter Priority mode) is a mode which allows you to set the shutter speed as you like. In this mode, the camera automatically sets the aperture (f-number) and ISO sensitivity to shoot a well-exposed photograph.
This mode is suitable when you want to take a shot freezing the motion of a moving subject, or capture trails of water or light.