Page 134 - Biomimetics: Technology Imitates Nature

age on film that is briefly exposed when a shutter is opened. In eyes the image
is focused by changing the shape of the lens, but cameras are focused by chang-
ing the distance of the lens from the film. 91

Focusing
This is the first step in taking a photograph. The same kind of focus-
ing of an image is also necessary in order for it to fall clearly onto the sen-

sitive retina in the eye. With cameras, this is done by hand or automati-
cally in more sophisticated models. Microscopes and telescopes, used to
see up close and far away, can also be focused, yet this process always in-
volves a certain loss of time.
The human eye, on the other hand, performs this process constantly
by itself, and very quickly. Furthermore, the method it employs is so su-
perior that it cannot possibly be imitated. Thanks to the muscles around
it, the lens sends the image onto the retina. Very flexible, this lens easily
changes shape, sharpening the point on which light falls by expanding or
contracting.
If the lens didn’t do this automatically—for instance, if we had to

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