Aperture Priority

Aperture Priority (A or Av)

Use the Aperture priority mode when you want to control the Depth of Field.

Aperture priority is a semi-automatic camera mode that allows the photographer to manually select the aperture while the camera automates the shutter speed.  The camera can also automatically control ISO in this mode, although you can manually set the ISO if you prefer. Aperture priority is designated by an A on most cameras, but Canon and Pentax use Av (for aperture value).

When using aperture priority mode, you change the aperture and the shutter speed is automatically changed to maintain proper exposure. Use this mode when you want to control the Depth of Field. Depth of field refers to the range of distance that appears acceptably sharp. By changing the f/stop we can control the DoF. The larger the f/number, the greater the depth of field and the smaller the f number the shallower the DoF.

Depth of Field

Depth of field is that zone both in front of and behind your subject that are in acceptably sharp focus. The focusing controls on most cameras are easy to use, providing you understand the factors that affect depth of field. To produce professional quality photographs, you must know how to control the depth of field.

A shallow depth of field results in a blurry foreground and background, whereas greater depth of field results in more overall sharpness.

Aperture priority mode won’t replace manual mode in the trickiest scenarios, but for many shots, the camera setting gives photographers the most control without adjusting the settings each time the lighting changes. It’s a great first step beyond auto mode for beginners, and a surprisingly powerful tool for experienced photographers.