Avideo camera is anoptical instrument that capturesvideos, as opposed to amovie camera, which records images onfilm. Video cameras were initially developed for thetelevision industry but have since become widely used for a variety of other purposes.
Video cameras are used primarily in two modes. The first, characteristic of much early broadcasting, islive television, where the camera feedsreal time images directly to a screen for immediate observation. A few cameras still serve live television production, but most live connections are forsecurity, military/tactical, and industrial operations where surreptitious or remote viewing is required. In the second mode the images are recorded to a storage device for archiving or further processing; for many years,videotape was the primary format used for this purpose, but was gradually supplanted byoptical disc,hard disk, and thenflash memory. Recorded video is used in television production, and more oftensurveillance and monitoring tasks in which unattended recording of a situation is required for later analysis.
Modern video cameras have numerous designs and use:
The earliest video cameras were based on the mechanicalNipkow disk and used in experimental broadcasts through the 1910s–1930s. All-electronic designs based on thevideo camera tube, such asVladimir Zworykin'sIconoscope andPhilo Farnsworth'simage dissector, supplanted the Nipkow system by the 1930s. These remained in wide use until the 1980s, when cameras based on solid-stateimage sensors such as thecharge-coupled device (CCD) and laterCMOSactive-pixel sensor (CMOS sensor) eliminated common problems with tube technologies such asimage burn-in and streaking and madedigital videoworkflow practical, since the output of the sensor is digital so it does not need conversion from analog.
The basis forsolid-state image sensors ismetal–oxide–semiconductor (MOS) technology,[1] which originates from the invention of theMOSFET (MOS field-effect transistor) atBell Labs in 1959.[2] This led to the development ofsemiconductor image sensors, including the CCD and later the CMOSactive-pixel sensor.[1] The first semiconductor image sensor was the charge-coupled device, invented at Bell Labs in 1969,[3] based onMOS capacitor technology.[1] TheNMOS active-pixel sensor was later invented atOlympus in 1985,[4][5][6] which led to the development of the CMOS active-pixel sensor atNASA'sJet Propulsion Laboratory in 1993.[7][5]
Practical digital video cameras were also enabled by advances invideo compression, due to the impractically highmemory andbandwidth requirements ofuncompressed video.[8] The most important compression algorithm in this regard is thediscrete cosine transform (DCT),[8][9] alossy compression technique that was first proposed in 1972.[10] Practical digital video cameras were enabled by DCT-based video compression standards, including theH.26x andMPEGvideo coding standards introduced from 1988 onwards.[9]
The transition todigital television gave a boost to digital video cameras. By the early 21st century, most video cameras weredigital cameras.
With the advent of digital video capture, the distinction between professional video cameras and movie cameras has disappeared as the intermittent mechanism has become the same. Nowadays, mid-range cameras exclusively used for television and other work (except movies) are termed professional video cameras.
Early video could not be directly recorded.[11] The first somewhat successful attempt to directly record video was in 1927 withJohn Logie Baird’s disc basedPhonovision.[11] The discs were unplayable with the technology of the time although later advances allowed the video to be recovered in the 1980s.[11] The first experiments with using tape to record a video signal took place in 1951.[12] The first commercially released system was Quadruplex videotape produced byAmpex in 1956.[12] Two years later Ampex introduced a system capable of recording colour video.[12] The first recording systems designed to be mobile (and thus usable outside the studio) were thePortapak systems starting with the Sony DV-2400 in 1967.[13] This was followed in 1981 by theBetacam system where the tape recorder was built into the camera making a camcorder.[13]
While some video cameras have built in lenses, others use interchangeable lenses connected via a range of mounts. Some likePanavision PV andArri PL are designed for movie cameras while others likeCanon EF andSony E come from still photography.[14] A further set of mounts likeS-mount exist for applications like CCTV.
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