Automatic aperture

Glossary Terms

A camera lens has automatic aperture when the diaphragm remains fully open until the moment the shutter is released. At this moment the diaphragm will close down to the aperture the photographer had set previously, and open to the maximum aperture again once the shutter has closed. This is almost exclusively a feature of lenses for SLR cameras; it gives a bright image in the viewfinder for focusing and framing.