The easiest and most intuitive way to illustrate and understand the design and operation of the human eye has been to parallel its structure to a photographic camera or, in more recent times, a videocamera. This might sound paradoxical, because it is probably closer to the truth to assume that optical design of the photocamera was derived in some way from the eye's structure. The role and relevance of constitutive elements such as the cornea, iris, crystalline lens, and retina gain immediate insight from comparison with their technical counterparts (objective, diaphragm, focus adjustment, and photosensitive film), which are familiar to most people. With the advent of electronic photosensor matrices (digital cameras), the comparison can be pushed further, not only through the obvious equivalence between detector pixels and retinal photoreceptors, but also including on-board signal preprocessing to parallel with neuroretinal filtering and summation.
Use of the eye-camera comparison is not simply confined to the naïve description of the eye provided by encyclopedias or, at a higher level, by introductory optics manuals, but it is also exploited for meaningful scientific investigations. Even the purely optical characterization of ocular performances recalls what happens with reflex photocameras, where different objectives can be coupled to different camera bodies containing sensory and driving circuitry.
Online access to SPIE eBooks is limited to subscribing institutions.