Photography mastery - Basics
What is a shutter? And why does the speed matter?
A shutter is a curtain in front of the camera sensor. This stays closed until the camera fires. When the camera fires, the shutter opens. All of the light that passes through the lens aperture hits the camera sensor and creates a permanent image of a scene. After a determined period of time, the shutter will close and block any addition light from hitting the camera sensor. Essentially, a shutter is just a curtain that allows an amount of light to pass through.
Shutter speed is a beautiful tool that makes up one of the exposure triangle trio. (The other two being ISO and aperture). Opening the shutter on a camera for any period of time allows light to hit the camera's sensor. The more light that hits the sensor, the brighter the image will be.
The length of time the shutter is open is called the shutter speed. Most cameras will have a range of shutter speeds from 1/8000th of a second (which is incredibly fast), all the way down to being open for as long as 30 seconds in one photo.
As we've stated above, the longer a shutter is open, the more light is able to hit the camera sensor. More light means a brighter photo. Conversely, 1/8000th of a second is so fast that only a slither of light will hit the camera sensor.
Shutter speeds also depict how our photos will look, which can be used to brilliant creative control. Having a shutter speed that is super fast can freeze action. Freezing the subject usually gives very crisp photos but can take the sense of action and movement away depending on the subject. Slower shutter speeds can create a blurring, usually motion blur, where a subject is blurred depending on direction of movement throughout the photo.
How do I change the shutter speed of my exposure?
If you're in an automatic mode (other than shutter priority), the shutter speed will change without any user input, based of the meter reading of the scene.
To have full control of the shutter speed you need to be in either shutter priority (S mode on Nikon or Tv on Canon) or manual mode. Shutter priority (Tv on Canon stands for Time value and is the same setting with a different name) allows the user to set a shutter speed, with the camera adjusting the remaining exposure settings to keep the shutter speed. For example, you may want a shutter speed of 1/1000th of a second to freeze any motion. In shutter priority you'll dial in 1/1000th, you'll then observe the aperture and sometimes ISO change based on lighting conditions. But the shutter speed will remain constant.
Manual mode gives you complete control of the shutter speed, but it also requires you to change the ISO and aperture to create the correct exposure. Still wanting to shoot with 1/1000th of a second? You may have to adjust both ISO and aperture yourself. It isn't as scary as it sounds, it just takes a little time to learn.
Below is an example photo of a fast shutter speed, and a second, of the exact same scene, with a long exposure. Both photos were shot about 5 seconds apart. Notice how a slower shutter speed implies motion and makes the photo appear cleaner.