A camera is an optical instrument that captures a visual image. It works by focusing light from the scene onto a light-sensitive surface, such as film or a digital sensor. The lens is the part of the camera that controls the amount of light that enters the camera and the focus of the image. The lens is made up of a series of glass elements that bend the light rays so that they converge at the focal point. The focal point is the point at which the light rays meet after passing through the lens. The distance between the lens and the focal point determines the magnification of the image. A longer focal length lens will produce a more magnified image than a shorter focal length lens.