DK Science: Video
Video cameras are small television cameras that can capture images on a portable recording device, such as an in-built tape or the camera’s digital memory. Television pictures were not often recorded until 1956, when the first practical videotape machine was invented. Now compact cameras are used to capture the latest news from all around the world, family holidays, and special occasions.
Home cameras have become smaller and smaller as microelectronics has produced better chips and compact image sensors. Early camcorders used cathode ray tubes both to form the image and to display it. Now, most use CCD (charge-coupled device) sensors and colour liquid crystal displays (LCDs).
Professional cameras use wider tape to capture more detail. Their high-quality lenses and tough bodies allow broadcasters to record or transmit excellent images from almost anywhere. The latest cameras record images in digital form, which uses half the amount of tape because unnecessary information is not recorded.
The heart of a modern video camera is its CCD (charge-coupled device) sensor. This microchip turns an image from the camera lens into a electrical signal. Thousands of tiny, light-sensitive elements on the sensor’s surface charge up with electricity when they are exposed to the image. Each element then transfers its electrical charge to its neighbour until the all the charges that form the image have been read out in sequence.
