Fig. 46-1. Optical comparison of (A) the eye and (B) a miniature camera. Each has two refractive components: (1) an anterior (cornea and aqueous humor) and (2) a posterior (the lens of the eye), separated by an iris diaphragm. The lens systems have a focal length of 2 cm and 5 cm, respectively, and an aperture range of f2.5 to f11 and f2 to f22, respectively. The visual image, however, is not imprinted as on a film, but is coded and transmitted more as in television. C shows common refractive errors and their correction. Click for high resolution image.