A device that captures the light is Camera. Shutter, lens
and film are the essential component in a camera. In digital camera film is
replaced by CCD or CMOS sensor array. Shutter decides the quantum of light
falling on the film. Top layer of film
is made up light sensitive granules. When film is exposed to light, granules
get oxidized with respect to intensity of light. The exposed film is chemically
washed to make negative film. The negatives are used to create photos. The
sensitivity of film is described using ISO number. Higher the number results in
more sensitivity towards light.
Lens plays a dominant role in determining the cost and
quality of camera. Lion share of camera cost is attributed to lens.
Professional photographers will have lenses ranging from 35 mm, 50 mm, 85 mm up
to 200 mm. But, one can take photos without lens. The statement may evoke
surprise but it is a fact. A camera without lens is called 'Pin Hole Camera'.
The construction of the camera is simple. Take a rectangular metal or wooden
box. Place a film in one side of the box and close it. Make a very small hole
on the other side. This hole is technically called as aperture. Via aperture, light from outside scene (say
tree) falls on the film and an inverted image is formed. After getting
sufficient exposure to light the aperture has to be closed with a shutter.
Otherwise due to over exposure film will be washed out.
