Understanding Shutter Speed

Shutter speed is the length of time that the shutter is open, or the amount of time that the camera’s sensor views your scene. A fast shutter speed freezes action, while a slow shutter speed will create a “motion blur.”  A slow shutter speed may be used to convey a sense of movement — to show water flow, for example, or if you’re photographing a runner, you can use a slow shutter setting to convey a sense of speed.

Shutter speed is measured in seconds, or fractions of a second: 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, etc. (the speed typically doubles with each camera setting).

So how do you decide which shutter speed to use? Ask yourself what’s moving in the scene, and how you’d like to capture it — whether you want your image to have a sense of movement, or if you’d like to freeze movement. Movement typically freezes at 1/500th of a second or faster.

If you use a shutter speed slower than 1/60th of a second, you’ll likely need a tripod. It will be difficult to avoid holding your camera steady for this long, and you may get an unintentional blur in your image.

Remember that shutter speed affects exposure, so if you’re working in manual mode and change the shutter speed, you’ll also have to adjust the ISO and aperture to maintain exposure.

You may also choose to work in Shutter Priority Mode, usually indicated by a “Tv” or “S” symbol on your camera. In this semi-manual mode, you select the shutter speed and the camera will automatically select the proper aperture. A fast shutter speed will use a small depth of field (large aperture).

Understanding Exposure

If you want to venture out of your camera’s auto mode to have more control over your images, one of the most important things to understand is exposure, which determines how light or dark your photo will be.

If your camera doesn’t let in enough light, your photo will underexposed and you won’t see things very well. If you let in too much light, your photo will be overexposed – it’ll be too bright to see details. Your goal is to achieve perfect exposure by balancing three main elements: ISO, aperture, and shutter speed.

• ISO is the measure of the camera sensor’s light sensitivity.
• Aperture is the opening in a lens that can be adjusted to let more or less light hit a digital camera’s sensor.
• Shutter speed is the amount of time, expressed in fractions of a second, that the shutter is open to let light through the aperture.

ISO, aperture, and shutter speed all work together. These settings can help you achieve certain creative effects, but you have to keep in mind that if you adjust one setting, the other two will be affected. You’ll have to adjust all three in order to maintain perfect exposure. Refer to the chart below to see how they affect your photos.

Your DSLR should have a light meter to gage your exposure. If your meter is at 0, your photo is perfectly exposed; -2 is underexposed, and +2 is overexposed.

If your pictures are too bright, try upping your shutter speed, increasing your aperture, and/or reducing your ISO. If your pictures are too dark, reduce the shutter speed, decrease your aperture, and/or increase the ISO.