aperture definition in photography
aperture apÂ·erÂ·ture (Äp'Ér-chÉr) n. An opening, such as a hole, gap, or slit. A usually adjustable opening in an optical instrument, such as a microscope, a camera, or a telescope, that limits the amount of light passing through a lens or onto a mirror. The diameter of such an opening. The diameter of the objective of a telescope or microscope.