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alemán árabe búlgaro checo chino coreano croata danés eslovaco esloveno español estonio farsi finlandés francés griego hebreo hindù húngaro indonesio inglés islandés italiano japonés letón lituano malgache neerlandés noruego polaco portugués rumano ruso serbio sueco tailandès turco vietnamita

definición - tv camera

tv camera (n.)

1.television equipment consisting of a lens system that focuses an image on a photosensitive mosaic that is scanned by an electron beam

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tv camera (n.)

camera, television camera

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Professional video camera

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A professional video camera (often called a television camera even though the use has spread) is a high-end device for creating electronic moving images (as opposed to a movie camera, that records the images on film). Originally developed for use in television studios, they are now commonly used for corporate and educational videos, music videos, and direct-to-video movies.

There are two types of professional video cameras: High end portable, recording cameras (essentially, high-end camcorders) used for ENG and EFP image acquisition, and studio cameras which lack the recording capability of a camcorder, and are often fixed on studio pedestals. Portable professional cameras are generally much larger than consumer cameras and are designed to be carried on the shoulder.

Contents

History

File:Historical television camera.jpeg
Early studio television camera -- Gray box on right is the lens, gray box on top is the Viewfinder, sides are lowered to show internal electronics.

Professional television camera history has two main lines: the gradual shrinking of the camera as it became more versatile and self contained; and a progression of sensors from large insensitive tubes to smaller, much more sensitive tubes and finally to very small, very sensitive solid state chip imagers. Cameras that contained their own recording mechanisms did not appear until the early 1980s.

At the beginning, these cameras were very large devices, almost always in two sections. The camera section held the lens and tube pre-amps and other necessary electronics, and was connected with a large diameter multi-core cable to the rest of the camera electronics, usually mounted in a rack. The rack would be in a separate room in the studio, or in a remote truck. The camera head alone could not generate a video picture signal on its own. The video signal was output from the rack unit to the rest of the studio for switching and transmission. By the fifties, electronic miniaturization had progressed to the point where some monochrome cameras could operate stand alone and even be handheld. But the studio configuration remained, with the large cable bundle transmitting the signals back to the CCU (Camera Control Unit). The CCU in turn was used to align and operate the camera's functions, such as exposure, system timing, and video and black levels.

The first color cameras (1950s in the US, early 1960's in Europe), notably the RCA TK-40/41 series, were much more complex with their three (and in some models even four) pickup tubes, and the size and weight drastically increased. Handheld color cameras did not come into general use until the early 1970s, and the first ones were two pieces, a camera head shoulder unit that held the lens and tube section, and a backpack unit. The Ikegami HL-33 was the first of this type, but was followed a up by one piece cameras. These one piece cameras, (The HL-77 from Ikegami and the TK76 from RCA) made possible, (in combination with portable 3/4" U-matic VCRs) the introduction of Electronic News Gathering (ENG), which very rapidly replaced the 16mm film cameras that had been the dominant method for capturing news events. This established the standard operation in the field of a two person news crew, one operating the camera, and one carrying the shoulder strapped U-matic recorder and a boom microphone. The control layout (often called "form factor") for the camera's most important functions was also established with these cameras, and continues to define an ENG camera to this day.

In the early 80s, the first cameras with an on board recorder were brought to the market. The more successful of these used the Betacam recording system. At first these cameras used pickup tubes, and the recorders were of the removable type. Models with solid state CCD imagers came on the scene in the mid-80s. These brought multiple benefits. They were much more stable and less prone to drift than tube cameras, and didn't require a warm up or calibration time at the beginning of the day. They also were not prone to image burn in or lag caused by very bright light sources in the frame. The early models did not have the resolution or color quality of their tube counterparts, but successive models quickly pulled ahead of tube technology. Eventually, cameras with the recorder permanently mated to the camera head became the norm for ENG.

Studio camera technology did not stand still during this period. The camera electronics shrunk, and CCD imagers replaced the pickup tubes. The thick multi-core cables connecting the camera head to the CCU were replaced in the late seventies with triax connections, a slender video cable that carried multiple video signals, intercom audio, and control circuits, and could be run for a mile or more. As the camera innards shrunk, the electronics no longer dictated the size of the enclosure. But the box shape remained, as it was necessary to hold the large studio lenses, teleprompters, studio viewfinder, and other paraphernalia needed for studio and sports production. Electronic Field Production cameras were often mounted in studio configurations inside a mounting cage. This cage supported the additional studio accessories.

In the late 90s, as HDTV broadcasting commenced, HDTV cameras suitable for news and general purpose work were introduced. Though they delivered much better image quality, their overall operation was identical to their standard definition predecessors. New methods of recording for ENG cameras were introduced to supplant tape. Ikegami and Avid introduced EditCam in 1996, based on interchangeable hard drives. Panasonic introduced P2 cameras. These recorded a DVCPro signal on interchangeable flash card media. Several other data based recording systems were introduced, notably XDCam from Sony, and as of 2009, it remains to be seen what will become the predominant method of camera media for professional use in the 2010s.

Chronology

  • 1926 to 1933 "cameras" were a type of flying spot scanner using mechanical disk.
  • 1936 saw the arrival of RCA's iconoscope camera.
  • 1946 RCA's TK-10 studio camera used a 3" IO - Image Orthicon Tube with a 4 lens turret. The RCA TK-30 (1946) was widely used as a Field Camera.
  • The 1948 Dumont Marconi MK IV was an Image Orthicon Camera. Marconi's first camera was shown in 1938.[1] EMI cameras from the UK, were used in the US in the early 1960s, like the EMI 203/4.[2] Later in the 60s the EMI 2000 an EMI 2001.
  • In 1950 the arrival of the Vidicon camera tube made smaller cameras possible. 1952 saw the first Walkie-Lookie "portable cameras". Image Orthicon tubes were still used till the arrival of the Plumbicon.
  • The RCA TK-40 is considered to be the first color television camera for broadcasts in 1953. RCA continued it lead in the high-end camera market till the (1978) TK-47, last of the high-end tube cameras from RCA.[3]
  • Ikegami introduced the first truly portable hand-held TV camera in 1962.
  • Philips' line of Norelco cameras were also very popular with models such as PC-60 (1965), PC-70 (1967) and PCP-90 (1968 Handheld). Philips/BTS-Broadcast Television Systems Inc. later came out with an LDK line of camera, like its last high end tube camera the LDK 6 (1982). Philips invented the Plumbicon pick up Video camera tube in 1965, that gave tube cameras a cleaner picture. BTS introduced its first HandHeld Frame transfer CCD- Charge-coupled device-CCD camera the LDK90 in 1987.
  • Bosch Fernseh marketed a line of high end cameras (KCU, KCN, KCP, KCK) in the US ending with the tube camera KCK-40 (1978). Image Transform (in Universal City) used specially modified 24 frame KCK-40 for their "Image Vision" system. This had a 10 MHz bandwidth twice NTSC resolution. This was a custom pre HDTV video System. At its peak this system was used to make "Monty Python Live at the Hollywood Bowl" in 1982. This was the first major high-definition analog wideband videotape-to-film post production using a film recorder for film out.

Technology

Most professional cameras utilize an optical prism block directly behind the lens. This prism block (a trichroic assembly comprising two dichroic prisms) filters the image into the three primary colors, red, green, and blue, directing each color into a separate charge-coupled device (CCD) or Active pixel sensor (CMOS image sensor) mounted to the each face of the prism. Some high-end consumer cameras also do this, producing a higher-resolution image, with better color fidelity than is normally possible with just a single video pickup.

In both single sensor and triple sensor designs, the weak signal created by the sensors is amplified before being encoded into analog signals for use by the viewfinder and monitor outputs, and also encoded into digital signals for transmission and recording. The analog outputs are normally in the form of either a composite videosignal, which combines the color and luminance information to a single output; or an R-Y B-Y Y component video output through three separate connectors.

Studio cameras

Most studio cameras stand on the floor, usually with pneumatic or hydraulic mechanisms called pedestals to adjust the height, and are usually on wheels. Any video camera when used along with other video cameras in a studio setup is controlled by a device known as CCU (camera control unit), to which they are connected via an optical, Triax or Multicore cable. The camera control unit along with other equipments is installed in the production control room often known as Gallery of the television studio. When used outside a studio, they are often on tracks. Initial models used analog technology, but digital models are becoming more common. Some studio cameras are light and small enough to be taken off the pedestal and used on a cameraman's shoulder, but they still have no recorder of their own and are cable-bound. Cameras can be mounted on a tripod, a dolly or a crane.

ENG cameras

Sony camera head with Betacam SP dock recorder.

Though by definition, ENG (Electronic News Gathering) video cameras were originally designed for use by news camera operators, these have become the dominant style of professional video camera for most uses, from shooting dramas to documentaries, from music videos to corporate training. While they have some similarities to the smaller consumer camcorder, the following differences should be noted:

  • ENG cameras are larger and heavier, and usually supported by a shoulder stock on the cameraman's shoulder, taking the weight off of the hand, which is freed to operate the lens zoom control. The weight of the cameras also helps dampen small movements.
  • 3 CCDs are used instead of one, one for each primary color
  • They have interchangeable lenses.
  • All settings, white balance, focus, and iris can be manually adjusted, and automatics can be completely disabled.
  • The lens is focused manually and directly, without intermediate servo controls. However the lens zoom and focus can be operated with remote controls in a studio configuration.
  • Professional connectors - BNC for video and XLR for audio. There are at least two XLR audio inputs.
  • A complete timecode section is available, allowing time code presets; and multiple cameras can be timecode-synchronized with a cable.
  • "Bars and tone" are available in-camera (the color bars are SMPTE (Society of Motion Picture and Television Engineers) Bars, a reference signal that simplifies calibration of monitors and setting levels when duplicating and transmitting the picture. )
  • Recording is to a professional medium like some variant of Betacam or DVCPRO or Direct to disk recording or flash memory. If as in the latter two, it's a data recording, much higher data rates (or less compression) are used than in consumer devices.
  • The camera is mounted on tripods and other supports with a quick release plate.
  • A rotating behind-the-lens filter wheel, for selecting an 85A and neutral density filters.
  • Controls that need quick access are on hard physical switches, not in menu selections.
  • Gain Select, White/Black balance, color bar select, and record start controls are all in the same general place on the camera, irrespective of the camera manufacturer.
  • Audio is adjusted manually, with easily accessed physical knobs.
EFP Camera operator at a baseball game.

EFP Cameras

Electronic Field Production cameras are similar to studio cameras in that they are used primarily in multiple camera switched configurations, but outside the studio environment, for concerts, sports and live news coverage of special events. These versatile cameras can be carried on the shoulder, or mounted on camera pedestals and cranes, with the large, very long focal length zoom lenses made for studio camera mounting. These cameras have no recording ability on their own, and transmit their signals back to the broadcast truck through a triax or multicore cable.

Dock cameras

Some manufacturers build camera heads, which only contain the optical block, the CCD sensors and the video encoder, and can be used with a studio adapter for connection to a CCU in EFP mode, or various dock recorders for direct recording in the preferred format, making them very versatile. However, this versatility leads to greater size and weight. They are favored for EFP and low-budget studio use, because they tend to be smaller, lighter, and less expensive than most studio cameras.

A remote-controlled camera mounted on a miniature cable car for mobility.

Remote cameras

Remote cameras are typically very small camera heads designed to be operated by remote control. Despite their small size, they are often capable of performance close to that of the larger ENG and EFP types.

"Lipstick" cameras are so called because the lens and sensor block combined are similar in size and appearance to a lipstick container. These are either hard mounted in a small location, such as a race car, or on the end of a boom pole. The sensor block and lens are separated from the rest of the camera electronics by a long thin multi conductor cable. The camera settings are manipulated from this box, while the lens settings are normally set when the camera is mounted in place.

Block cameras are so called because the camera head is a small block, often smaller than the lens itself. Some block cameras are completely self contained, while others only contain the sensor block and its pre-amps, thus requiring connection to a separate camera control unit in order to operate. All the functions of the camera can be controlled from a distance, and often there is a facility for controlling the lens focus and zoom as well. These cameras are mounted on pan and tilt heads, and may be placed in a stationary position, such as atop a pole or tower, in a corner of a broadcast booth, or behind a basketball hoop. They can also be placed on robotic dollies, at the end of camera booms and cranes, or "flown" in a cable supported harness, as shown in the illustration.

See also

References

Notes

Bibliography

  • Zettl, H. 2006 "Television Production Handbook", Thomson Wadsworth, ISBN 0-534-64727-8

External links

 

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