Video Camera

video camera is a camera used for electronic motion picture acquisition (as opposed to a movie camera, which records images on film), initially developed for the television industry but now common in other applications as well.The earliest video cameras were those of John Logie Baird, based on the mechanical Nipkow disk and used in experimental broadcasts through the 1918s–1930s. All-electronic designs based on the video camera tube, such as Vladimir Zworykin's Iconoscope and Philo Farnsworth's image dissector, supplanted the Baird system by the 1930s.

Video cameras are used primarily in two modes. The first, characteristic of much early broadcasting, is live television, where the camera feeds real time images directly to a screen for immediate observation. A few cameras still serve live television production, but most live connections are for security, military/tactical, and industrial operations where surreptitious or remote viewing is required. 

Modern video cameras have numerous designs and uses.

  • Professional video cameras, such as those used in television production, may be television studio-based or mobile in the case of an electronic field production (EFP). Such cameras generally offer extremely fine-grained manual control for the camera operator, often to the exclusion of automated operation.
  • Camcorders combine a camera and a VCR or other recording device in one unit; these are mobile, and were widely used for television production, home movies, electronic news gathering (ENG) (including citizen journalism), and similar applications.
  • Webcams are video cameras which stream a live video feed to a computer.

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 earlier recorded the images on film). Originally developed for use in television studios, they are now also used for music videos, direct-to-video movies, corporate and educational videos, marriage videos etc. 

History

The earliest video cameras were mechanical flying-spot scanners which were in use in the 1920s and 1930s during the period of mechanical television. Improvements in video camera tubes in the 1930s ushered in the era of electronic television. Earlier, cameras were very large devices, almost always in two sections. The camera section held the lens and tube pre-amplifiers and other necessary electronics, and was connected to a large diameter multicore cable to the remainder of the camera electronics, usually mounted in a separate room in the studio, or a remote truck. The camera head could not generate a video picture signal on its own. The video signal was output to the studio for switching and transmission. 

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 four) pickup tubes, and their size and weight drastically increased. The Ikegami HL-33, the RCA TK45 and the Thomson Microcam were portable two piece color cameras introduced in the early 1970s. For field work a separate VTR was still required to record the camera's video output. Typically this was either a portable 1" reel to reel VTR, or a portable 3/4" U-matic VCR. 

At first all these cameras used tube-based sensors, but charge-coupled device (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 took 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 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. 

In the late 1990s, 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 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.In 2000s, major manufacturers like Sony, Philips introduced the digital professional video cameras. These cameras used CCD sensors and recorded video digitally on flash storage.

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.

Studio cameras

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. 

Studio camera with teleprompter

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 camera operator's shoulder, but they still have no recorder of their own and are cable-bound. Cameras can also be mounted on a tripod, a dolly or a crane, thus making the cameras much more versatile than previous generations of studio cameras. 

Webcam

webcam is a video camera that feeds or streams its image in real time to or through a computer to a computer network. When "captured" by the computer, the video stream may be saved, viewed or sent on to other networks travelling through systems such as the internet, and e-mailed as an attachment. When sent to a remote location, the video stream may be saved, viewed or on sent there.The most popular use of webcams is the establishment of video links, permitting computers to act as videophones or videoconference stations. Other popular uses include security surveillance, computer vision, video broadcasting, and for recording social videos.

Webcams can be used as security cameras. Software is available to allow PC-connected cameras to watch for movement and sound,recording both when they are detected. These recordings can then be saved to the computer, e-mailed, or uploaded to the Internet. In one well-publicised case,a computer e-mailed images of the burglar during the theft of the computer, enabling the owner to give police a clear picture of the burglar's face even after the computer had been stolen.

Webcams can be used to take video clips and still pictures. Various software tools in wide use can be employed for this, such as PicMaster (for use with Windows operating systems), Photo Booth (Mac), or Cheese (with Unix systems).Special software can use the video stream from a webcam to assist or enhance a user's control of applications and games. Video features, including faces, shapes, models and colors can be observed and tracked to produce a corresponding form of control. 

With very-low-light capability, a few specific models of webcams are very popular to photograph the night sky by astronomers and astro photographers. Mostly, these are manual-focus cameras and contain an old CCD array instead of comparatively newer CMOS array. A webcam's CCD response is linear proportional to the incoming light. Therefore, webcams are suitable to record laser beam profiles, after the lens is removed. The resolution of a laser beam profilerdepends on the pixel size. Commercial webcams are usually designed to record color images. The size of a webcam's color pixel depends on the model and may lie in the range of 5 to 10µm. However, a color pixel consists of four black and white pixels each equipped with a color filter (for details see Bayer filter). 

First developed in 1991, a webcam was pointed at the Trojan Room coffee pot in the Cambridge University Computer Science Department (initially operating over a local network instead of the web). The camera was finally switched off on August 22, 2001.The first commercial webcam, the black-and-white QuickCam, entered the marketplace in 1994, created by the U.S. computer company Connectix (which sold its product line to Logitech in 1998). QuickCam was available in August 1994 for the Apple Macintosh, connecting via a serial port, at a cost of $100. Jon Garber, the designer of the device, had wanted to call it the "Mac-camera", but was overruled by Connectix's marketing department; a version with a PC-compatible parallel port and software for Microsoft Windows was launched in October 1995.

Webcams typically include a lens, an image sensor, support electronics, and may also include a microphone for sound. Various lenses are available, the most common in consumer-grade webcams being a plastic lens that can be screwed in and out to focus the camera.Support electronics read the image from the sensor and transmit it to the host computer. The camera pictured to the right, for example, uses a Sonix SN9C101 to transmit its image over USB. Typically, each frame is transmitted uncompressed in RGB or YUV or compressed as JPEG. Some cameras, such as mobile-phone cameras, use a CMOS sensor with supporting electronics "on die", i.e. the sensor and the support electronics are built on a single silicon chip to save space and manufacturing costs.

Cameras such as Apple's older external iSight cameras include lens covers to thwart this. Some webcams have built-in hardwired LED indicators that light up whenever the camera is active, sometimes only in video mode.The fraudulent process of attempting to hack into a person's webcam and activate it without the webcam owner's permission has been called camfecting. The remotely activated webcam can be used to watch anything within the webcam's field of vision, sometimes the webcam owner itself. Camfecting is most often carried out by infecting the victim's computer with a virus that can provide the hacker access to the victim's webcam. 

Webcams allow for inexpensive, real-time video chat and webcasting, in both amateur and professional pursuits. They are frequently used in online dating and for online personal services offered mainly by women when camgirling.YouTube is a popular website hosting many videos made using webcams. News websites such as the BBC also produce professional live news videos using webcams rather than traditional cameras.

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