Television Cameras: Parts, Function & Types

Published by Emil Abraham,

Despite their electronic complexity, all television cameras (including the consumer video cameras) consist of three main parts. The first is the lens, which selects a certain field of view and produces a small optical image of it. The second part is the camera itself, with its imaging, or pickup, device that converts into electrical signals the optical image as delivered by the lens. The third is the viewfinder, which shows a small video image of what the lens is seeing. Some cameras have a small foldout screen that enables you to forgo looking through an eyepiece to see the camera picture.
All television cameras, whether digital or analog, big or small, work on the same basic principle: the conversion of an optical image into electrical signals that are reconverted by a television set into visible screen images. Spe­cifically, the light that is reflected off an object is gathered by a lens and focused on the imaging (pickup) device. The imaging device is the principal camera element that trans­ duces (converts) the light into electric energy—the video signal. That signal is then amplified and processed so that it can be reconverted into visible screen images.
With these basic camera functions in mind, we can ex­ amine step-by-step the elements and the processes involved in the transformation of light images into color television images. Specifically, we look at (1) the beam splitter and (2) the imaging device.
The beam splitter contains various prisms and filters. They separate the white light that passes through the camera lens into the three light beams—red, green, and blue, usually referred to as RGB. These three primary colors are then electronically "mixed" into the many colors youseeon thetelevision screen. Because all of these prisms and filters are contained in a small block, the beam splitter is often called the prism block.
Once the white light that enters the lens has been divided into the three primary colors, each light beam must be translated into electrical signals. The principal electronic component that converts light into electricity is called the imaging device. This imaging, or pickup, device consists of a small solid-state device (about the size of a button on a standard telephone keypad) normally called a chip or, technically, a charge-coupled device (CCD). A CCD normally contains hundreds of thousands or, for a high-quality CCD, millions of image-sensing elements, called pixels (a word made up of pix, for picture, and els for elements), that are arranged in horizontal and vertical rows.
Pixels function very much like tiles that compose a complete mosaic image. A certain amount of such elements is needed to produce a recognizable image. If there are relatively few mosaic tiles, the object m a y b e recognizable, but the picture will not contain much detail. The more and the smaller the tiles in the mosaic, the more detail the picture will have. The same is true for CCDs: the more pixels the imaging chip contains, the higher the resolution of the video image.

White balance
Our eyes and brain make a wonderful partnership. Together, they automatically adjust the exposure of whatever it is we are looking at to achieve a balanced image. More importantly, they correct any colour cast so that anything white actually looks white, regardless of the ambient light.
Unfortunately, digital cameras are not so clever. They record the scene as they see it − within their limitations. This is why, in tricky lighting conditions, we have to set the white balance to ensure the result we want. It is also why, to get results of the optimum colour, we usually have to tell the camera the colour temperature of the light falling on to the scene.
In simple terms, light is made up of the three primary colours − red, green and blue. These colours are present in different proportions in all light sources. For example, tungsten lights have more red in them than fluorescent lights, which are greener. This proportion of colours is measured as the colour temperature.
In short, this control (white balance) adjusts the camera circuits’ color-balance to suit the color quality of the prevailing light and ensure that white surfaces are accurately reproduced as neutral.

Read more on the Lens system

Camera chain
When looking at a high-quality studio camera, you can see that it is connected by cable to an electrical outlet. This cable connects the camera to a chain of equipment necessary to produce pictures. The major parts of the camera chain are (1) the actual camera, called the camera head because it is at the head of the chain; (2) the camera control unit, or CCU; (3) the sync generator that provides the synchronization pulses to keep the scanning of the various pieces of television equipment in step; and (4) the power supply.

CCU
Most of the camera functions (framing, focus, etc) are controlled normally by a camera operator, whilst certain functions (colour balance, shutter speed, etc) are controlled remotely by the CCU operator. This allows the camera operator to concentrate on framing and composition without being distracted by technical issues. At the same time the CCU operator, who is a specialist in the more technical issues, is concentrating on the quality and consistency of the pictures.
The picture below shows a bank of four CCU controllers which are embedded into the desk workspace in front of the CCU operator. In front of the operator are four monitors showing the pictures from each camera. These controls are relatively advanced and allow the CCU operator to:
  • Control the iris, shutter speed, black level, gain, etc.
  • Adjust colour balances
  • Monitor and adjust a wide range of technical parameters
  • Send signals to the camera operator



The sync generator produces electronic synchronization pulses—sync pulses—that keep in step the scanning in the various pieces of equipment (cameras, monitors, and videotape recorders). It produces synchronization signals with a high level of stability and accuracy. These devices are used to provide a master timing source for a video facility.
The power supply generates the electricity (direct cur­rent) that drives the camera. In a studio the power supply converts AC (alternating current) to DC (direct current) power and feeds it to the cameras.
The camera cable feeds all the CCU functions to the camera and transports the video signals from the camera back to the CCU.
Types of cameras
Television cameras can be classified by their electronic makeup and by how they are used. As you may have guessed, cameras grouped by electronic makeup are either analog or digital. Cameras classified by function are for either studio or ENG/EFP use.

Classification by electronic makeup (analog vs. digital)
Although most cameras are digital, regardless of whether they are large studio cameras or small camcorders, there are nevertheless many analog cameras still in use, mainly because of their high initial cost (such as Sony Betacam) and their remarkably good picture quality (such as the S-VHS and Sony Hi8 camcorders). Regardless of the type of camera, all of them—analog and digital, large and small—start out with an analog video signal. The light that is transported through the lens to the beam splitter and from there to the imaging device remains analog through­ out. Even after the translation of the three RGB light beams by the CCDs, the resulting video signals are still analog. But from there analog and digital part company.
In the analog camera, the video signal remains analog throughout the processing inside the camera and during he recording, assuming that the video tape recorder (VTR) is also analog. In the digital camera, however, the analog RGB video signals are digitized and processed right after leaving the CCDs.

Classification by function
Despite the differences between analog and digital, standard or high-definition, high-end or low-end, televi­sion cameras fall into four groups:
(1) studio cameras,
(2) ENG/EFP cameras and camcorders,
(3) consumer cam­corders, and
(4) prosumer camcorders.
This classification is more useful because it is based on the primary produc­tion function of the camera, not on its electronic makeup. Some camera types are better suited for studio use, others for the coverage of a downtown fire or the production of a documentary on pollution, and still others for taking along on vacation to record the more memorable sights.

Studio Cameras
The term studio camera is generally used to describe high-quality cameras, including high-definition televi­sion (HDTV) cameras. They are so heavy they cannot be maneuvered properly without the aid of a pedestal or some other camera mount.
Studio cameras are used for various studio productions, such as news, interviews, and panel shows, and for daily serial dramas, situation comedies, and instructional shows that require high-quality video. But you can also see these cameras used in such "field" locations as concert and convention halls, football and baseball stadiums, tennis courts, and medical facilities.
The obvious difference between the standard studio camera and ENG/EFP and consumer cameras is that stu­ dio cameras can function only as part of a camera chain; all other camera types can be self-contained, capable of delivering a video signal to a recording device, such as a VTR, without any other peripheral control equipment. Because the picture quality of a studio camera is deter­ mined by the VO who is operating the CCU, there are relatively few buttons on studio cameras compared with ENG/EFP models.
ENG/EFP Cameras and Camcorders
Cameras for electronic news gathering (ENG) and electronic field production (EFP) are portable, which means that they are usually carried by a camera operator or put on a tripod. They are also self-contained and hold the entire camera chain in the camera head. With their built-in control equipment, ENG/EFP cameras and camcorders are designed to produce high- quality pictures (video signals) that can be recorded on a separate VTR, on a small VTR or disk-recording device that is docked with the camera, or on a built-in VTR or disk recorder. As noted, when docked with a recording device, the camera forms a camcorder, ENG/EFP camcorders operate on the same basic principle as the smaller consumer models except that the CCDs, the video-recording device, and especially the lens are of much higher quality. In conforming to a tapeless production environment, an ever-increasing number of camcorders use small hard drives or optical discs as the recording device.
The ENG/EFP camera has many more buttons and switches than does a studio camera or a home camcorder mainly because the video control (CCU) functions, the VTR operation, and the audio control functions must be managed by the camera operator. Fortunately, you can preset many of these controls using an electronic menu or by switching to automatic, similar to the auto-controls on a consumer camcorder. These automatic features make it possible to produce acceptable pictures even under dras­ tically changing conditions without having to manually readjust the camera.
[The picture quality of the high-end ENG/EFP camera is so good that it is frequently used as a studio camera. To make it operationally compatible with regular studio cameras, the ENG/EFP model is placed in a specially made camera frame; a large external tally light is added; the small (1 -inch) eyepiece viewfinder is replaced with a larger (5- or 7-inch) one; and zoom and focus controls that can be oper­ated from the panning handles are added. The ENG/EFP lens, which offers a relatively wide-angle view, must be substituted with a zoom lens that is more suitable to the studio environment. Other important conversion factors include an intercom system for the camera operator and a cable connection to the CCU that enables the video operator to control the camera from a remote position just like a standard studio camera.]
Consumer Camcorders
Most consumer cameras have a single-chip imaging device (CCD) and a built-in VTR/storage. All have automated features, such as auto-focus, which focuses on what the camera presumes to be the target object, and auto-iris, which regulates the incoming light. In addition to the regular eyepiece viewfinder, most consumer camcorders have a foldout screen on which you can see the picture you are taking without having to hold the camera close to your eye.
Even very small digital camcorders produce astonish­ ingly good pictures and, if everything is done correctly, acceptable sound.
Prosumer Camcorders
There are smaller camcorders on the market that incorporate many of the aforementioned features of professional camcorders. These high-end con­sumer models, called prosumer camcorders, are finding more and more acceptance in news and documentary pro­ductions. High-definition video (HDV) digital camcorders are the prosumer model for high-definition television. The HDV camcorder captures video with three fairly high-quality imaging devices. They can be the stan­ dard high-quality CCDs or high-resolution CMOS chips, which are similar to CCDs but draw less power. This is an important consideration when using a relatively small battery as the energy source.
Advantages of Professional Camcorders
  • Professional camcorders have three high-resolution CCDs, whereas most consumer camcorders have only one. Each of the three CCDs is assigned to a specific color (red, green, or blue) as provided by the beam splitter. Three- CCD cameras produce truer colors than do cameras with a single CCD, especially in low light levels.
  • Professional camcorders have larger and sturdier recording devices (VTRs or disks).
  • Professional camcorders use larger and better-quality lenses.
  • Professional camcorders have better audio systems. The microphone inputs, preamplifiers, and sound controls are less noisy and more flexible than the simple camera microphone of the consumer camcorder.
  • Professional camcorders have more operational con­ trols that let you manually adjust the camera to a variety of production conditions. The automatic controls of the small camcorders may seem like an advantage over manual operation, but this is true only in ideal situations. If you shoot under adverse conditions, such as in dim light, ex­ tremely bright sunshine, or noisy surroundings, or if you want to achieve a certain mood, the automatic controls will no longer suffice for producing optimal images.
  • Professional camcorders have larger batteries.
  • Professional camcorders have smoother mechanisms for zooming in and out, better focus controls, and larger and higher-resolution viewfinders.