Porsche 911 During the Le Mans 24 Hours – 1/30 second shutter speed
What Is Shutter Speed?
Every camera has a physical shutter, like a curtain, that opens and closes to expose the sensor to the light coming in through your lens when you press the shutter button. The length of time that this shutter is open is called the shutter speed and also sometimes referred to as ‘exposure time’. Shutter speed is one of the three sides of our exposure triangle, along with aperture and ISO, that allow us to control the brightness of our image. These three things work together to give us both creative control and also exposure control for our photos. We can select a fast shutter speed that freezes any action in a photo, or we can select a slow shutter speed that introduces ‘motion blur’ to any moving objects within our image.
Combining a panning motion of the camera (left to right, or right to left movement) with a slow shutter speed can be used to give a sense of speed, as in the car photo that opens this article. It gives a sense of movement to the car, but doesn’t blur out any of the car’s detail if you keep the car in the same spot in the frame as you pan. With the running water in the photo below, the static camera but blurry water gives the water a sense of fluid motion. When you are taking a photo with your camera in a semi-automatic (TV/AV) or manual exposure mode, then consideration must be given to the required shutter speed for your subject. Most of the time we are looking to freeze our subject with a fast enough shutter speed and capture that one singular moment, but sometimes the creative effect of a slower speed can also be desirable. What shutter speed is fast enough? Well that will depend on your subject! Further down this article there’s a handy reference guide that’ll get you started with some typical scenarios.
How is shutter speed measured?
A camera’s shutter speed is measured as a fraction of a second for all speeds that are under a second. For example 1/250 means one two hundred and fiftieth of a second, or 1/8 means one eighth of a second. The shutter speeds that are available to choose from might vary depending on the type of camera you are using, but typically a DSLR will go from 1/4000 all the way to 30 seconds. Further down this page you’ll find a handy reference chart that shows all of the standard options in between. Some pro level DSLRs will allow even faster speeds than 1/8000 and many will have ‘BULB’ mode for shooting at longer than 30 seconds. This mode keeps the shutter open for as long as you hold down the shutter button.
If you double your shutter speed then the shutter will be open for half the amount of time so you half the amount of light that’s reaching the sensor. This is therefore equivalent to a 1-stop change in exposure. To maintain the same overall exposure in our image, we must remember the exposure triangle and either double our ISO, or open up our aperture by one stop to compensate.
Water running through a creek – 14 second shutter speed