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Optics imitates an eye

 A camera has a convex lens, a shutter, a diaphragm and
 light sensitive recording material, or film.
  « Image example

The lenses are either convex or concave. They can also be a combination of them so that one side is convex and the other concave. The other side can also be a plane. A convex lens gathers light while a concave lens disperses light.

A magnifying glass is a convex lens. It gathers parallel light beams coming from afar into one focal point.

Optics imitates the functioning of an eye. An eye resembles camera with a convex lens. In front of it there is the iris or a diaphragm that regulates the aperture size. The iris regulates the amount of light coming into the eye. A small aperture lets only a small amount of light in, but the picture is clear. The eyelids function as shutters. The film is replaced by retina.

Seeing is not continuous, instead, the eye forms individual pictures just like a movie camera or a video camera. A person moving at 40 km/h sees the road only at every 1 meter's distance; that is why the visual field is hazy in the very front and on the sides. The picture on the retina is upside-down, but the optic nerves turn it over.

A camera was born when it was discovered that one could place a convex lens and a shutter over the hole of a pinhole camera, and a chemically light-sensitive film on the back wall. At first, film plates were used, later on, mostly film cartridges.

A picture is formed on the film upside-down. A lens gathers plenty of light onto the picture. This makes it possible to take pictures rapidly.

The main types of lenses:

1. Fix focus lenses:

  • fixed focus - mostly no focusing
  • camera has to be moved when composing different ratios

2. Zoom lenses:

  • focal distance can be changed up to 16-fold or even more


Optics.org: Photonics Resources for Scientiests and Engineers. [optics.org]

Optics for Kids. [www.opticalres.com/kidoptx.html]


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