Lesson 7: Introduction to Shutter Speed
What is Shutter Speed?
Shutter speed is the amount of time the shutter is open and a measurement of time. It’s basically the timer for light coming into the camera. Shutter speed is the length of time the shutter curtain is open and light is exposed to the sensor. Shutter speed is measured in time increments ranging from full seconds to a fraction of a second (sometimes up 1/8000). The larger the shutter speed denominator, the faster the shutter opens and closes exposing less light to the camera sensor. When you use a lower shutter speed, the shutter is open longer and exposes more light to the image sensor.
Shutter Speed is one of the three pillars of the exposure triangle (ISO, Aperture and Shutter Speed). In addition to controlling light for proper exposure, shutter speed is also used artistically. You can use a very fast shutter speed to freeze the action of hockey game, or use a slower speed to create motion blur cause by flowing water.
Shutter Speed (Video Clip)
Here is another great quirky 34 second video clip from Canon Australia that demonstrates the difference between fast and slow shutter speeds.
How Does the Shutter Work?
The shutter in your camera is a curtain that covers the image sensor and remains closed until the camera fires. When you press the shutter button, the camera fires, the shutter curtain opens and exposes the sensor to light. The light that passes through the lens and to the camera sensor creatures your photo.
Mechanical Operation of a Shutter
The actual mechanical shutter in a DSLR camera consists of two curtains we’ll call A and B. When you press the shutter button on your camera, curtain A rises to allow light to hit the sensor, then curtain B rises immediately after to meet curtain A and block the light. Next, the curtains reset and the process is repeated.
Prior to the movement of the shutter curtains, there is a mirror at a 45 degree angle in front of the shutter that moves up and out of the way to enable the camera to take the photo. When you are composing your image, light passes through the lens, reflects off the mirror and through to the viewfinder so you can see what’s happening. Mirrorless cameras are the exception to this process because they do not have a reflective mirror popping up and down.
Shutter Speed Settings
Each camera has a range of preset shutter speeds available. Common shutter speeds you’re likely to see in most cameras are: 1/40, 1/60, 1/125, 1/250, 1/ 500, 1/1000, 1/2000, etc. Shutter speeds on your camera are usually displayed as whole numbers. So a display of 125 is actually 1/125th of a second. Quotation marks are used shutter speeds of one second or more. For example, 2 seconds may be displayed as 2”0 in your camera viewfinder. The Bulb setting leaves the shutter open as long as you like.
Shutter speeds on your camera usually double with increment. When you have settings like 1/30, 1/60, 1/125, 1/500, 1/1000 your doubling the speed as you move to faster shutter speeds. It’s just like changing your aperture – as you increase the aperture by one increment, you let in half as much light.
Holding Camera using a Slow Shutter Speed
You need use a shutter speed that is fast enough to avoid what is known as camera shake. It’s nearly impossible for most people to hold a camera perfectly still. If you’re using a shutter speed slower than 1/60, you’re should probably use a tripod so you don’t blur your photos from movement while you’re holding the camera. If it’s difficult for you to hold the camera still, no problem. Try using a shutter speed that is one over twice the focal length of your lens. So if you’re using a 50mm lens, use a shutter speed of at least 1/100.
The Basics of Shutter Speed (video from B&H)
In this video clip from B&H Photo, they show a couple of great examples of how shutter speed can be used to freeze action, create cool motion blur effects, and long shutter effects like taking images at night. This is a great video for creative ideas on how you can use shutter speed to create amazing images.