Aperture is most simply understood to control depth of field and is simplified if you think of it like a pupil in an eye.
Aperture is the opening in a lens through which light passes into the camera – the wider the aperture, the more light that enters. Aperture is most simply understood to control depth of field and is simplified if you think of it like a pupil in an eye. Aperture is measured in f-numbers or f-stops (the ratio of the lens focal length divided by the diameter of the entrance pupil of the aperture).