aperture

A wider aperture — a smaller f-number — passes more light and gives less depth of field. Most lenses are at their sharpest a stop or two down from wide open, and stopping down too far loses sharpness again to diffraction, which is why f/8 or thereabouts is a common working setting for aircraft in daylight.

Nearby in Photography

• aperture priority — An exposure mode in which you set the aperture and the camera chooses the shutter speed.
• autofocus — Automatic focusing, driven by the camera's detection of contrast or phase differences in the scene.
• back-lit — Lit from behind, with the light source on the far side of the subject from the camera.
• blue hour — The twilight period before sunrise and after sunset when the sky is deeply and evenly blue.