Canon® Speedlite System Digital Field Guide, 2nd Edition

Glossary

AE (Automatic Exposure)

A general-purpose shooting mode where the camera automatically sets the aperture and shutter speed using its metered reading. On some cameras, the ISO settings are also automatically set.

AE/AF Lock

A camera setting that allows you to lock the current exposure and/or autofocus setting prior to taking a photo. This button lets you recompose the scene without holding the Shutter button halfway down.

AF-assist illuminator

Useful in low-light and low-contrast shooting situations, a feature that automatically projects a red grid onto your subject to aid the camera's autofocusing system. The AF (autofocus) assist illuminator is located on the bottom front of the flash. The AF-assist beam is compatible with most recent Canon cameras, helping the camera to focus properly in poor light.

ambient light

The natural or artificial light within a scene. This is also called available light.

aperture

Also referred to as the diaphragm or f-stop setting of the lens. The aperture controls the amount of light that is allowed to enter through the camera lens. The higher the f-stop number setting, the smaller the aperture opening on the lens. Larger f-stop settings are selected by lower numbers, such as f/2 or f/1.2. The larger the aperture, the less depth of field the image will possess. A smaller aperture means that the image will have more depth of field, and that more of the background will be in focus.

Aperture-priority (Av)

A camera setting where you choose the aperture, and ...