Professional video camera
|This article needs additional citations for verification. (June 2012)|
A professional video camera (often called a television camera even though the use has spread beyond television) 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 tapeless camcorders) used for electronic news gathering (ENG) and electronic field production (EFP) image acquisition, and television 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.
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 video camera tubes to smaller, much more sensitive tubes and finally to very small, very sensitive solid state charge-coupled device (CCD) and active pixel sensor (CMOS) imagers. Betacam 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 multicore 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 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 1960s 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 - the first generation of cameras were split into a camera head unit (where the body of the camera, containing the lens and pickup tubes was, and held in the right hand of the operator) connected via a wire to a portable video recorder (attached in the style of a backpack).
The Ikegami HL-33 and RCA TK76 was the first of the two piece type, where the cameras was connected to a portable 3/4" U-matic VCR to record the image. This two-piece recording mode survived until the early 1980s, when the advent of "camcorders" - the merging of a camera and recorder as a single unit - was brought to the market in the early 1980s.
Electronic news-gathering (ENG) cameras rapidly replaced the 16mm film cameras because the cost of shooting on film was significantly more than shooting on a reusable tape - although many news items until the 1990s were still shot on 16mm because it was a format universal around the world, whereas video tape introduced many incompatable formats.
At first these cameras used tube based sensors, but CCD imagers came on the scene in the mid-80s, bringing numerous benefits. Early CCD cameras could not match the colour or resolution of their tube counterparts, but the benefits of CCD technology, such as introducing smaller and lightweight cameras, a better and more stable image (that was not prone to image burn in or lag) and no need for calibration meant development on CCD imagers quickly too off and, once rivaling and offering a superior image to a tube sensor, began displacing tube-based cameras - the latter of which were all but virtually disused by the early 1990s.
Eventually, cameras with the recorder permanently mated to the camera head became the norm for ENG. In studio cameras, the camera electronics shrank, 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, and meant camera operators achieve shots thanks to this shrinking. However, the box shape remained, as it is necessary to hold the large studio lenses, teleprompters, electronic viewfinder (EVF), 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 video tape, tapeless cameras. Ikegami and Avid introduced EditCam in 1996, based on interchangeable hard drives. Panasonic introduced P2 cameras. These recorded a DVCPro signal on interchangeable flash memory card media. Several other data storage device 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. Sony also introduced SxS (S-by-S), a flash memory standard compliant to the Sony and Sandisk-created ExpressCard standard.
- 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. A TK-30 is simply a TK-10 with a portable camera control unit.
- The 1948 Dumont Marconi MK IV was an Image Orthicon Camera. Marconi's first camera was shown in 1938. EMI cameras from the UK, were used in the US in the early 1960s, like the EMI 203/4. Later in the 60s the EMI 2000 and 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 its lead in the high-end camera market till the (1978) TK-47, last of the high-end tube cameras from RCA.
- 1954 RCA's TK-11 studio camera used a 3" IO - Image Orthicon Tube with a 4 lens turret. The RCA TK-31 (1954) was widely used as a Field Camera. A TK-31 is simply a TK-11 with a portable camera control unit. There is some commonality between the TK-11/TK-31 and the earlier TK-10/TK-30.
- 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, California) 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.
Most professional cameras utilize an optical prism block directly behind the lens. This prism block (a trichroic assembly comprising two dichroic prisms) separates 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 face of each 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 video signal, 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.
Most television 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 multiple-camera setup is controlled by a device known as CCU (camera control unit), to which they are connected via a Triax, Fibre Optic or the almost obsolete multicore cable. The CCU along with genlock and other equipment is installed in the production control room (PCR) often known as the Gallery of the television studio. When used outside a formal television studio in outside broadcasting (OB), they are often on tripods that may or may not have wheels (depending on the model of the tripod). Initial models used analog technology, but are now obsolete, supplanted by digital models. Studio cameras are light and small enough to be taken off the pedestal and the lens changed to a smaller size to be used on a Multiple-camera setup'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, thus making the cameras much more versatile than previous generations of studio cameras. These cameras have a tally light, a small signal-lamp used that indicates, for the benefit of those being filmed as well as the camera operator, that the camera is 'live' - i.e. its signal is being used for the 'main program' at that moment.
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 video productions, from dramas to documentaries, from music videos to corporate video training. While they have some similarities to the smaller consumer camcorder, they differ in several regards:
- ENG cameras are larger and heavier (helps dampen small movements), and usually supported by a camera shoulder support or shoulder stock on the camera operator's shoulder, taking the weight off the hand, which is freed to operate the zoom lens control.
- The camera mounts on tripods with Fluid heads and other supports with a quick release plate.
- 3 CCDs or CMOS active pixel sensors are used, one for each of the primary colors
- They have interchangeable lenses.
- The lens is focused manually and directly, without intermediate servo controls. However the lens zoom and focus can be operated with remote controls with a television studio configuration operated by a camera control unit (CCU).
- 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, all in the same general place on the camera, irrespective of the camera manufacturer, such as Gain Select, White/Black balance, color bar select, and record start controls and not in menu selection.
- All settings, white balance, focus, and iris can be manually adjusted, and automatics can be completely disabled.
- Professional BNC connectors for video out and genlock in.
- Can operate an electronic viewfinder (EVF) or external CRT viewfinder.
- At least two XLR input connectors for audio are included.
- Direct slot-in for portable wireless microphones.
- Audio is adjusted manually, with easily accessed physical knobs.
- A complete time code section is available, allowing time presets; multiple-camera setups can be time code-synchronized or jam synced to a master clock.
- "Bars and tone" are available in-camera (the SMPTE color bars (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 video compression) are used than in consumer devices.
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, fiber optic or the virtually obsolete multicore cable.
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.
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.
- Zettl, H. 2006 "Television Production Handbook", Thomson Wadsworth, ISBN 0-534-64727-8
|Wikimedia Commons has media related to Video cameras.|