How does a camera work? For example, how does the picture get
transferred to the film?
Well, there are basically 2 parts to the problem: first
making an image, and second recording the image. To make
the image, you need to use lenses, and fancier cameras
have fancier lense systems to get better images. To
actually get an image where the film is, the lenses
take the incoming light and focus it there. The science
of forming images like this is called "optics".
To record the image, all ordinary cameras use film,
which contains chemicals that change their nature when
exposed to light. These chemicals are on such tiny grains
that you can have to blow up a picture many times to see
the "graininess". A recent development is to use sensitive
electronic devices to record the image, rather than chemicals
deposited on a film. I think Kodak's disk camera does this,
and the procedure is also used on many astronomical telescopes,
and the pictures taken by space vehicles. I assume it is also
what is used in modern video cameras, though I do not know much
about them (they do not need such good resolution as still cameras
anyway, but they need to take a lot of pictures quickly).
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Update: June 2012