A lens is a transparent piece of glass that, when light rays pass through it by refraction, either concentrates or disperses them. Lenses are employed in telescopes and other magnifying equipment because of their enlarging capabilities. For the purpose of gathering light, they are used in cameras. A lens is a device that directs light toward a focused area. The lens of a film camera provides light to the film strip, whereas the lens of a digital camera (such as a DSLR or mirrorless camera) sends light to the digital sensor. Modern lens technology also enables the correction of presbyopia. When lenses are inserted into your cornea directly, they move with your eye, giving you crisp peripheral and center vision.