All video cameras contain 3 major components – the
lens, imager, and recorder. The lens gathers and
focuses the light on the imager, which is normally
a charge coupled device (CCD) or CMOS sensor IC.
Finally, the recorder will encode the video signal
into a form that can be stored. Commonly, the optics
and imager are known as the camera section.
The optic lens is the first component in the camera
section’s light path. The optics normally have one
or more the following adjustments:
1. aperture – controls the amount of light
2. zoom – controls the field of view
3. shutter speed – captures continuous motion
In most consumer units, these adjustments are
automatically controlled by the video camera’s
electronics, normally to maintain constant exposure
onto the imager.
The imager is the “eye” of the camera, housing a
photo sensitive device or devices. The imager works
to convert light into an electronic video signal
through an elaborate electronic process. The
camera lens projects an image to the imager surface,
exposing the photo sensitive array to the light.
The light exposure is then converted into an electrical
charge. Towards the end of the timed exposure, the
imager will convert the accumulated charge into a
continuous analog voltage at the imager’s output
terminals.
The third piece, the recorder, is responsible for
writing the video signal to a recording medium,
such as magnetic videotape. The recording function
involves many steps of signal processing, and
historically, the recording process introduced
some distortion and noise to the stored video,
such that the playback of stored signal may not
retain the same detail as the original live feed.
All but the most primitive of video cameras will
also need to have a recorder controlling section
which will allow you to control the camera. You
can also swich the recorder into playback mode
for reviewing your recorded footage.
The image you recorded doesn’t need to be limited
to what appeared in the view finder. For a
documentation of events such as those used by the
police, the fields of view will overlay such
things as the time and date of the recording along
the top and bottom of the image.
As you can probably tell now, a high definition
video camera is very complex indeed. There are
several other parts involved as well, although the
above are the most important. A HD video camera
is very complex in build, making it something
that is more than worth the time it takes to create.
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