Shutter Speed: Your Camera’s Eyelid
If the aperture is like the pupil in a human eye, then the camera’s shutter is like an eyelid – light can only enter while it is open. The ‘shutter speed’ refers to the length of time that this shutter is open for, allowing light to fall on to the camera’s sensor in order to create an exposure.
Shutter speed is measured in fractions of a second, with a ‘fast’ shutter speed including settings such as 1/250th of a second or 1/1000th of a second while a ‘slow’ shutter speed setting would be 1/15th of a second, or even two seconds.
Slow shutters speeds
Opening the shutter for longer means that more light will enter, enabling brighter exposures, even in darker environments. A slower shutter speed also enables motion to be recorded as blurred elements in a scene. This is because anything that moves during the time the shutter is open will be recorded in multiple places in the frame.
Sometimes you may want to capture movement in this way. For example, if you wanted to show the fluid grace of a dancer, you may want the arc of their outstretched limb to be visible as it swings across the image frame, while their face, which didn’t move while the shutter was open, remains sharp.
Avoiding camera shake
An unwanted side effect to watch out for, however, is camera shake. This is when the photographer’s movements cause the whole image to be blurred. The speed of the shutter that you will need to use in order to avoid this happening depends on your personal ability to hold steady – some people can still all motion easily, while others naturally tremble more. A general guideline is the ‘Reciprocal Rule’: this dictates that the shutter speed should be equal to or higher than the focal length of your lens (see page REF). For instance, if you are using an 85mm lens, your shutter speed should be 1/85th of a second or faster in order to avoid camera shake. Test yourself by taking shots at each different shutter speed and noting when camera shake starts to affect your images.
You can eliminate the risk of camera shake by using a tripod (and by even using the time delay on the shutter release so you aren’t in any contact with the camera at the point that the exposure is made). However, tripods can be very limiting in portrait photography as they slow or restrict your ability to change your angle. Instead, you could widen your aperture (see page REF) or raise your ISO (see page REF) in order to enable you to use a faster shutter speed. Alternatively, try to stabilise yourself by leaning against the back of chair or on a door frame or adjust your stance to a more stable one in order to minimise any unintentional movements.
Fast shutter speeds
In brighter environments, or when you want to freeze motion, a faster shutter speed is needed. This limits the amount of light that can reach the camera’s sensor. If you wanted to use a wide aperture on a bright day for example, you would need to combine it with a fast shutter speed to avoid the image becoming too overexposed. Equally, if you want to photograph a moving subject without any motion blur, a fast shutter speed will be required.
How to set the shutter speed
Select Shutter Priority on your DSLR’s Mode dial. On Nikon cameras, this is marked as ‘S’, while on Canon cameras it’s ‘Tv’ (for Time value). Turn your main control dial to adjust the shutter speed. It will usually be displayed as a full number, rather than a fraction: e.g. a shutter speed of 1/100th of a second will show as ‘100’, while a two second shutter speed will display as ‘ 2″ ‘. The standard shutter speeds are 1 second, 1/2 second, 1/4 second, 1/8 second, 1/15 second, 1/30 second, 1/60 second, 1/125 second, 1/250 second, 1/500 second and 1/1,000 second. Each adjustment up or down the scale will roughly halve or double the length of time the shutter is open, and also halve or double the amount of light that reaches the sensor.