Shutter speed is the length of time the sensor is exposed to light when a photo is taken. It is also called exposure time. A short time records an instant; a long time records everything that happens while the shutter is open, including any movement of the subject or the camera.
How the shutter works
In most cameras the shutter is a pair of curtains in front of the sensor. When the button is pressed, the first curtain opens to start the exposure and the second follows to end it. Many mirrorless cameras and all phones can also use an electronic shutter, which simply switches the sensor on and off. The effect on exposure is the same in both cases.
How shutter speed is written
Most shutter speeds are fractions of a second: 1/60, 1/250, 1/1000. Cameras often display only the bottom number, so “250” means 1/250 s. Speeds of one second or longer are shown with a quotation mark: 2″ means two seconds. This is an easy place to make a mistake, because 4 and 4″ are very different exposures.
The standard full-stop sequence is:
30 s – 15 s – 8 s – 4 s – 2 s – 1 s – 1/2 – 1/4 – 1/8 – 1/15 – 1/30 – 1/60 – 1/125 – 1/250 – 1/500 – 1/1000 – 1/2000 – 1/4000
Each step halves or doubles the time, and therefore the light. Going from 1/60 s to 1/125 s halves the light; going from 1/60 s to 1/30 s doubles it. As with aperture, cameras offer thirds of a stop in between.
Two effects
Shutter speed changes brightness and it changes how movement is recorded. A fast speed lets in little light and freezes motion. A slow speed lets in a lot of light and allows motion to blur. The creative side of this is covered in the next two lessons; here the focus is on getting a sharp, correctly timed exposure.
Camera shake and the handheld limit
Hands are never perfectly still. If the shutter stays open long enough, that small movement blurs the entire picture. The traditional guideline is the reciprocal rule: use a shutter speed at least as fast as 1 divided by the focal length.
| Focal length (full frame) | Slowest safe handheld speed |
|---|---|
| 24 mm | 1/30 s |
| 50 mm | 1/60 s |
| 100 mm | 1/125 s |
| 200 mm | 1/250 s |
| 400 mm | 1/500 s |
On an APS-C camera multiply the focal length by 1.5 (1.6 for Canon) before applying the rule. On high-resolution cameras it is wise to go one stop faster still. Image stabilisation in the lens or body allows speeds three or more stops slower, but it only corrects movement of the camera. It does nothing for a subject that moves.
Typical shutter speeds
- General daylight photography: 1/250 s
- Posed portrait: 1/125 s
- Indoor handheld with a standard lens: 1/60 s
- Tripod landscape at dusk: 1 s to 30 s
Shutter Priority and Bulb
In Shutter Priority mode, marked S on most cameras and Tv on Canon, you choose the shutter speed and the camera sets the aperture. It is the natural mode when movement is the main concern. If the aperture value blinks in the display, the lens cannot open wide enough or close far enough for the chosen speed; change the ISO or the shutter speed.
Most cameras stop at 30 seconds. For longer exposures, Bulb mode keeps the shutter open as long as the button, or a remote release, is held.
Common mistakes
- Confusing camera shake with poor focus. If nothing in the frame is sharp, the cause is usually shake.
- Misreading 2″ as 1/2 s.
- Relying on stabilisation to photograph moving people at 1/15 s.
- Pressing the shutter button sharply on a tripod. Use the two-second self-timer or a remote release.
- Not checking the shutter speed in Aperture Priority when the light fades.
Practice exercise
- Set Shutter Priority and Auto ISO. Zoom to about 50 mm and switch stabilisation off if possible.
- Handheld, photograph a page of printed text at 1/250, 1/125, 1/60, 1/30, 1/15 and 1/8 s.
- View each frame at 100% and find the slowest speed that is still sharp. That is your personal handheld limit at that focal length.
- Turn stabilisation on and repeat to see how many stops it gains.
Next in this series: How Shutter Speed Affects Motion Blur, Fast vs Slow Shutter Speed Examples and The Exposure Triangle Explained. You can also browse all photography lessons.
