Monday, November 12, 2007

How Camcorders Work

Today,camcorders are everywhere. They have been a familiar sight and have changed our world as we know it. People take them everywhere: to school plays, sports events, family reunions and even births! When you go to a popular tourist spot, you are surrounded by them. Camcorders have really taken hold in the United States, Japan and many other countries around the world because they are an extremely useful piece of technology that you can own for under $300 (or more than $100,000) depending on your budget. It's just amazing what these devices can do and they are so simple to use and the quality of the picture is just outstanding. We'll take a closer look inside one of these devices and find out just what is going on. We'll look at analog and digital and explore the inner workings to find out just what makes them tick.

The basics

There are two basic parts to a camcorder:

  • A camera section, consisting of a CCD, lens and motors to handle the zoom, focus and aperture

  • A VCR section, in which a typical TV VCR is shrunk down to fit in a much smaller space
The cameras funtion is to recieve visual information and interpret into an electronic video signal The VCR component is exactly like the VCR connected to your tv except its shrunken down to fit the case. it recieves the electronic signal and records it onto magnetic tape for later playback

A third component, the viewfinder, receives the video image as well, so you can see what you're shooting. Viewfinders are actually small, black-and-white or color televisions, but many modern camcorders also have larger full color lcd screens. there are many other features on analog camcorders but these are the basics. digital camcorders have all the same components except that they use an additional component that takes the analog signal and converts it into bytes of data. instead of storing the signal on magnetic tape it records the picture and sound as 1s and 0s Digital camcorders are so popular because you can copy 1s and 0s very easily without losing any of the information you've recorded. Analog information, on the other hand, "fades" with each copy -- the copying process doesn't reproduce the original signal exactly. video info from digital cams can also be downloaded onto a computer and edited, emailed, or manipulated.


Like a film camera, a camcorder "sees" the world through lenses. In a film camera, the lenses serve to focus the light from a scene onto film treated with chemicals that have a controlled reaction to light. In this way, camera film records the scene in front of it: It picks up greater amounts of light from brighter parts of the scene, and lower amounts of light from darker parts of the scene. The lens in a camcorder also serves to focus light, but instead of focusing it onto film, it shines the light onto a small semiconductor image sensor. This sensor, a charge-coupled device (CCD), measures light with a half-inch (about 1 cm) panel of 300,000 to 500,000 tiny light-sensitive diodes called photosites

Each photosite measures the amount of light (photons) that hits a particular point, and translates this information into electrons (electrical charges): A brighter image is represented by a higher electrical charge, and a darker image is represented by a lower electrical charge. Just as an artist sketches a scene by contrasting dark areas with light areas, a CCD creates a video picture by recording light intensity. During playback, this information directs the intensity of a television's electron beam as it passes over the screen.

Of course, measuring light intensity only gives us a black-and-white image. To create a color image, a camcorder has to detect not only the total light levels, but also the levels of each color of light. Since you can produce the full spectrum of colors by combining the three colors red, green and blue, a camcorder actually only needs to measure the levels of these three colors to be able to reproduce a full-color picture.

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