W. Satar, M.D.
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Simple Comparison of the Human Eye to a Camera
Bionics studies help improve and develop technology that imitates nature.
There are the proverbial two sides to the "comparing an eye to a camera" coin. One side is merely factual -- the human eye is like this, and the camera is like that. The other side is more metaphysical -- and more controversial. But whatever side you're most interested in, the eye-camera coin is an interesting feature in the progressing knowledge of optics and bionics.
Both the camera and the human eye have a lens that focuses light into an inverted image. One major difference between the two lenses, though, is that while a camera lens moves closer or farther from an object in order to bring it into focus, the lens of the human eye stay stationary. To bring an object into focus, muscles in the eye respond to instructions from the brain and change the shape of the lens, thus sharpening the image.
Retina (Film or Sensor)
Additionally, the eye's retina is like a camera's film or sensor onto which light is cast. In the eye, light passes through the lens and hits the retina, where rods and cones help transform the received image into electric impulses that are sent along the optic nerve to the brain. While both the retina and a camera's film or sensor are all highly sensitive to light, the eye is much more so, and performs much better in the dark -- even without a flash.
To allow the right amount of light, both the eye and a camera have an aperture. The eye's version is its iris working together with the pupil, which, just like a camera aperture, widens or narrows depending on the amount of ambient light. Therefore, just the right amount of light hits either the eye's retina or camera's film or sensor so as to present a clear, discernible image.
The eye-camera discussion sometimes entwines with the creation-evolution debate. Creationists point to the eye as evidence of design in nature, while evolutionists point to the eye as simply a point of progress in evolutionary history. Interestingly, the publication "Popular Photography" asserted that "comparing the camera to the human eye isn’t a fair analogy. The human eye is more like an incredibly advanced supercomputer with artificial intelligence, information-processing abilities, speeds and modes of operation that are far beyond any man-made device, computer or camera.” Whatever your view is, the eye continues to be a source of inspiration in the optics and bionics fields.