When you press the button of the camera to take picture you hear a distinctive familiar sound which is nothing but the sound of the shutter movement. A shutter is a curtain in front of the camera sensor which remains closed till the time we press the shutter button to take picture. When we press the shutter button the shutter opens and light passes through the aperture to the sensor hence the image is recorded.
Lets understand how the shutter works.
From the above image you can make out the placement of the shutter. When we press the shutter button the mirror goes up and shutter opens. There are two curtains. First curtain shutter and second curtain shutter. Below image explains the different stages of the shutter movement. Duration of the entire process depends on the duration of time we want the sensor to be exposed.
You must be wandering what is the need of two shutter curtains. This is to facilitate faster shutter speed. When we use faster shutter speed, both the shutter curtain work concurrently.
Shutter technology is evolving. There has been a significant change in the way the old traditional shutter use to work. During the film era it was vital to have a mechanical shutter in all the cameras. This is because the pre-developed film was light sensitive. Most of the compact camera and mobile camera don’t use a traditional shutter mechanism. Shutter less cameras are likely to have more noise in the image. This is because these cameras consistently sends power to the sensor and when the shutter button is pressed it sends more power to record image. More power is equals to more noise.
We are likely to see professional shutterless cameras in future but for now DSLRs with traditional shutter curtain, this system is the most preferred system.
Measuring shutter speed is very easy to do. It is the amount of time the shutter remains open for the exposure. Suppose if your shutter speed is 500, it remains open for 1/500th of a second. Similarly if the shutter speed is 60 it remains open for 1/60th of a second. It can go as slow as 30 seconds to as fast as 1/8000th of a second depend upon the camera you are using. Another significant mode in shutter speed is B or Bulb mode. Till the time you keep your finger on your shutter button, the shutter will remain open. It is used for longer exposure which is more than 30 seconds and primarily controlled by a remote.