Digital Camcorders

in Video-format

A camcorder is an electronic device that combines a video camera and a video recorder into one unit. Equipment manufacturers do not seem to have strict guidelines for the term usage. Marketing materials may present a video recording device as a camcorder, but the delivery package would identify content as video camera recorder. In order to differentiate a camcorder from other devices that are capable of recording video, like mobile phones and digital compact cameras, a camcorder is generally identified as a portable, self contained device having video capture and recording as its primary function. The earliest camcorders employed analog recording onto videotape. Tape based camcorders use removable media in the form of video cassettes. Nowadays, digital recording has become the norm, with tape being gradually replaced with other storage media such as internal flash memory, hard drive and SD card.

Camcorders contain 3 major components: lens, imager, and recorder. The lens gathers and focuses light on the imager. The imager (usually a CCD or CMOS sensor on modern camcorders, earlier examples often used vidicon tubes) converts incident light into an electrical signal. Finally, the recorder converts the electric signal into video and encodes it into a storable form. More commonly, the optics and imager are referred to as the camera section.

The lens is the first component in the light path. The camcorder's optics generally have one or more of the following adjustments: aperture or iris to regulate the exposure and to control depth of field, zoom to control the focal length and angle of view, shutter speed to regulate the exposure and to maintain desired motion portrayal, gain to amplify signal strength in low light conditions, neutral density filter to regulate the exposure. In consumer units, the above adjustments are often automatically controlled by the camcorder's electronics, but can be adjusted manually if desired. Professional units offer direct user control of all major optical functions.

The imager converts light into electric signal. The camera lens projects an image onto the imager surface, exposing the photosensitive array to light. The light exposure is converted into electrical charge. At the end of the timed exposure, the imager converts the accumulated charge into a continuous analog voltage at the imager's output terminals. After scan out is complete, the photosites are reset to start the exposure process for the next video frame.

The recorder is responsible for writing the video signal onto a recording medium (such as magnetic videotape.) The record function involves many signal processing steps, and historically, the recording process introduced some distortion and noise into the stored video, such that playback of the stored signal may not retain the same characteristics as the live video feed. All but the most primitive camcorders imaginable also need to have a recorder controlling section which allows the user to control the camcorder, switch the recorder into playback mode for reviewing the recorded footage and an image control section which controls exposure, focus and white balance.

In 1983 Sony released the first consumer camcorder the Betamovie BMC-100P. It used a Betamax cassette and could not be held with one hand, so it was typically resting on a shoulder. In the same year JVC released the first camcorder based on VHS-C format. In 1985 Sony came up with its own compact video cassette format, Video8. Both VHS-C and Video8 had their benefits and drawbacks, and neither won the format war. In 1985, Panasonic, RCA, and Hitachi began producing camcorders that recorded to full sized VHS cassette and offered up to 3 hours of record time. These shoulder mount camcorders found a niche with videophiles, industrial videographers, and college TV studios. Super VHS (S-VHS) full sized camcorders were released in 1987 which exceeded the broadcast quality of the day and provided an inexpensive way to collect news segments or videographies. Sony matched this with the release of Hi8, an upgraded version of Video8.

In 1986 Sony introduced the first digital video format, D1. Video was recorded in uncompressed form and required enormous bandwidth for its time. In 1992 Ampex used D1 form factor to create DCT, the first digital video format that utilized data compression. The compression utilized discrete cosine transform algorithm, which is used in most modern commercial digital video formats. In 1995 Sony, JVC, Panasonic and other video camera manufacturers launched DV, which quickly became a de-facto standard for home video production, for independent film making and for citizen journalism. In the same year Ikegami introduced Editcam the first tape less video recording system. In 2000 Panasonic launched DVCPRO HD, expanding the DV codec to support high definition. The format was intended for use in professional camcorders and used full size DVCPRO cassettes. In 2003 Sony, JVC, Canon and Sharp introduced HDV, the first truly affordable high definition video format, which used inexpensive MiniDV cassettes.

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Paul Polkinghorne has 1 articles online

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This article was published on 2012/02/24