The human eyes operate like a camera. The cornea is transparent and provides the first objective lens of the eye. The lens is the zoom: adjusting focus to all distances. The pupil is controlled by the iris, a colored circular muscle with the ability to contract like the diaphragm of a camera to adapt to different lighting conditions. The retina, like a photographic film on which light is recorded, turns the photons into electrical energy. This energy is then transmitted through the optic nerve to the brain that transforms it into images.