Aperture

The English name is IRIS Aperture, Aperture is used to control the light through the lens into the fuselage in the amount of light sensitive surface of the device, which is usually within the lens. We usually say the aperture value F2.8, F8, F16, etc. is Aperture "factor" is a relative aperture, not the aperture of physical size, and Aperture's physical aperture and the camera to the PC devices (film or CCD or CMOS)