Just for Newbies

Aperture & shutter speed

Written by Gail Bjork

A quick guide to understanding aperture and shutter priority modes.

Mode dialA digital camera may have manual as well as semi-automatic modes that let you control aperture and shutter speed. Together, aperture and shutter speed determine how a photo is exposed.

The faster the shutter speed, the larger the opening of the lens (ie. smaller aperture number). Conversely, the slower the shutter speed, the smaller the lens opening.

Aperture-priority (AV) mode

When using aperture-priority, also known as Av mode, you manually select the aperture and the camera automatically sets the shutter speed.

The aperture is the opening in a lens that admits light onto the camera sensor and is varied by changing the size of the opening. It’s diameter is stated as an f-stop.

Aperture-priority mode is often used to control depth-of-field, the area a photo is sharp in front and back of where you focus on the main subject.

Shutter-priority (TV*) mode

Shutter speed relates to how long the camera’s shutter stays open after you depress the shutter-release button. Shutter speed is measured in seconds, such as 1/125th. A slow shutter speed produces a longer exposure time.

For shutter-priority mode (Tv), you select the shutter speed and the aperture adjusts automatically. Use shutter-priority mode when you want to control action in a photo either to freeze the action of fast moving subjects or to create a sense of movement, such as the movement of a cascading waterfall.

See our Shutter Speed Chart to learn to learn the effects of using different shutter speeds.

*Time Value

About the author

Gail Bjork

Gail Bjork, who is passionate about digital photography, is the owner and editor of Digicamhelp.Gail is the author of three illustrated ebooks about digital photography. A number of her photos and digital photography related articles appear at other websites.In 2006, a series of her photos, People in the Louvre, were exhibited at the Underground Photo Gallery
in Iisalmi Finland. Eight of her photos taken in the Florida scrub are on permanent exhibition at Parrish Medical Center in Titusville, Florida.Gail served twelve years as an elected member of The School Board of Palm Beach County, Florida, one of the largest school districts in the U.S. She has also been the editor of a small town newspaper and a free-lance writer. Gail and her husband owned and ran several small businesses.