The Differences Between the Human Eye & a Camera Lensby Clare Edwards
Strictly speaking, a camera's lens is too simple to be comparable with the whole eye; however, an entire camera can meaningfully compared to the human optical system. A camera's lens is analogous to the human cornea; photographic film or light sensors can be compared to the retina. Both systems can adjust the amount of light they allow in, by means of the iris in a human eye or the aperture control in a camera. There are also a number of notable differences -- not least of which is the obvious one that the human eye is an organic, biophysiological entity rather than a comparatively simple, human-made mechanical device.
A camera lens is similar in some regards to the human cornea. The chief difference is that a traditional lens is fixed in shape. In order to obtain a different focal length, it's necessary to add or remove lenses, or move the lens closer or further away from the object. In contrast, the human cornea can change its shape to focus on close or distant objects. Muscles inside the eye pull on the cornea to flatten it or relax to allow it to become more convex. While high-technology lenses are being developed that can mimic this property, they're not commonly available yet.
The lens of a camera is typically made from a hard, transparent material. In the past, glass was usually used for camera lenses; nowadays they are often made from plastics, which are cheaper and less prone to cracking or smashing. The human cornea, in contrast, is made from a soft organic substance.
A camera lens alone is a relatively simple structure. While it may require significant technical and manufacturing know-how to create one, a lens is in essence a curved section of transparent material with a frame that allows it to be attached to the camera. The eye, on the other hand, includes not just a lens but numerous complex structures necessary for sight.
Unlike a camera, the human eye is part of a sophisticated information processing system. Once the eye sees an image, it is transmitted to the brain via the optic nerve; the image received by the eye is thus subjective as opposed to objective. A camera, on the other hand, is essentially a dumb system; extra processing needs to be added to cope with different color temperatures, for example. The human retina is also more sensitive than even the most advanced and specialized cameras, able to derive useful information even in very low light levels. Certain cameras may be able to perceive stimulus invisible to the human eye or perform specific function the human eye can't, but the eye is still a more sophisticated mechanism overall.
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