Image illustrating light beams passing through two biconvex or converging lenses, which act as a simple telescope. This simulation shows parallel beams of monochromatic light striking a converging lens (the objective) at left. The rays are then bought to a focus and cross at the focal point of the objective. These, now diverging, rays then strike the second converging lens at the right (the eyepiece). On emerging from the eyepiece, at the extreme right of the picture, the rays are again parallel. In real telescopes, the objective lens is much bigger than the eyepiece, because a large objective lens can collect more light.