Glossary Definition


The aperture, or iris of a lens is an adjustable diaphragm within the lens system. It controls the amount of light coming through the lens and also affects the image’s depth-of-field. It is measured by an f-number (ƒ/#) or f-stop, which refers to the ratio of the lens’s focal length to its aperture’s diameter.

Please see our glossary entry for f-number for more information.

Full Glossary