HowStuffWorks Autopsy:
Inside a Camcorder
Imagine that you want to draw a picture of a flower. First, light travels from the flower to your eye, which collects the light. Then, your eye sends a message to your brain, and your brain interprets the message so you know what the flower looks like. Finally, your brain sends a signal to your hand, telling it how to move the pencil across the page.
A camcorder
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If you use a camcorder to film the flower, the same things happen. Light from the flower travels through the camcorder's lens, which is like the lens of your eye. The light then hits a charge-coupled device (CCD) inside the camcorder. The CCD is a light sensor, just like the retina inside your eye. It records the intensity and color of light for each pixel of the picture.
Inside a camcorder
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A recording head transfers this information to the tape, much like your hand uses a pen to draw a picture. The head is magnetic, and it records the image by magnetizing the tape in a pattern that a player can read. A small motor keeps the tape moving, and a series of rollers holds it at the right tension so it doesn't tangle or break.
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On the left, a CCD, on the right, the recording head
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The camcorder even has a part that's like your brain. A processor receives signals from all the buttons and switches and sends out the necessary commands. The camcorder also has a printed circuit board (PCB) and lots of cables that play the part of a nervous system. They carry information back and forth between the CCD, the processor and the recording head.
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On the left, the viewfinder, on the right, the LCD screen
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This electronic nervous system connects other parts as well. It carries the picture from the CCD to the viewfinder and the LCD screen. Both of these parts have the same purpose - they let you see the image that you're recording. The PCB and cables also carry sound signals between the microphone and the recording head. In addition, they connect the battery to all the parts that need power, including the CCD, the recording head and the motors that move the tape and adjust the focus.
Here's how it all comes together:
The CCD creates a picture using super-tiny squares called pixels. This camera's CCD has about 320,000 pixels. The CCD works by measuring light at areas called photosites. As photons of light hit the photosites, the photosites release electrons. The CCD measures the number of electrons at each site. Areas with more electrons are brighter, and areas with fewer are darker. The result is a grayscale image.
Most people want their pictures to be in color, so most CCDs have a color filter. The filter lets the CCD measure red, green and blue light at specific photosites. The CCD uses information about each color to determine the final color for every pixel.
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