What do your eyes and the digital camera in your pocket have
in common? A lot more than you may think! Surprisingly, the human eye and a regular
digital or film camera share a lot of similar properties. Cameras and eyes have three very similar
components:
Lens
Both the
eyes and cameras contain some sort of lens.
With the eye, the cornea acts as a lens in addition to another lens in
the eye. In the case of a camera, the
lens is typically made up of several pieces of specially shaped glass. Lenses
transmit and refract light in a way that allows things to be seen in
focus.
Iris and Pupil
The iris in the eye performs the same
function as a diaphragm in a camera.
They both act to control the amount of light being let in the eye or the
camera. This is also referred to as the
aperture in a camera. The pupil will appear larger in dark places and smaller
in bright ones; it expands or contracts to let more or less light into the
eye. The same goes for the aperture of a
camera.
Retina/Sensor
When light is let into the eye or the camera,
something must be there to pick up this light and turn it into an image. In the eye, this is referred to as the retina. In a camera, it is the image sensor for
digital, and film for analog cameras. The
retina uses photoreceptor cells called cones and rods to pick up individual
parts of an image including light and color.
This is much like pixels on a digital camera’s image sensor.
When light enters the eye or a camera, it is refracted in
much the same way. The image is
essentially projected to the back of the eye or the camera, but flipped. For people, the brain corrects the image so
it is displayed in the proper orientation.
In a digital camera, the image processor does this work, and it is
corrected in developing for a film camera.
While there are many similarities between the eye and
cameras, there remain several differences.
Most notably, eyes and cameras are comprised of very different
materials, with eyes being organic and cameras inorganic. The way color is detected is also different
in the eye and the camera. In the eye,
color is picked up by the cones, while color detection involves several filters
applied to the sensor in a camera. Eyes
also contain fluids such as tears and blood to provide lubricant and
nourishment. Cameras don’t need
nourishment.
