In photography, aperture is located in the lens and it is the size of the opening of the lens. Some lenses have fixed apertures, but most photographic lenses have variable apertures to control the amount of light entering the lens. The size of the opening also has a secondary effect on the photograph, as the diaphragm also changes the angle at which the light passes through the lens. Like the pupil in your eye, the aperture diaphragm opens and controls the amount of light passing through the lens. The bigger the aperture is, the more depth of field you will have.