The eye and a camera have a lot in common' They both have compound lenses'

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The Eye and the Camera
The eye and a camera have a lot in common. They
both have compound lenses. To focus a camera
you move the lens backward or forward. The eye
is focused by the ciliary muscle which stretches
the lens, changing its shape.
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Part of the Eye
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The iris, just like the aperture in a camera,
controls the amount of light that enters the eye.
The aperture in a camera protects the film from
over exposure. The iris in the eye protects the
sensitive retina from light damage
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The retina is like the film in a camera, covering
the back of the eye. It contains millions of
photoreceptor cells. These cells convert light
rays into electrical signals that are sent to the
brain through the optic nerve. The signals from
both eyes are combined and converted into sight
by the brain.
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Perception
The way that you see objects is not always the
way that they actually are. Your brain causes
you to see objects a certain way. The brains
interpretation of visual stimuli is called
perception.
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• www.pbs.org/wnet/brain/illusions/index.html