How Does Broadcast Cameras Work
Part I
Camera information at bottom of folio.
Cameras:
The Nuts
West ith all that has gone earlier as background, we tin can at present plough to the first in a series of modules on the photographic camera and its associated equipment.
Camera Imaging Devices
T he very heart of a video photographic camera is its imaging device. The first Goggle box cameras used rather large tubes, as shown on the left.
Some early colour cameras had four of these tubes (for red, blue, light-green, and luminance), which explains why early on color TV cameras weighed more than than 200 kilograms (500 pounds) and had to exist hauled around in trucks.
A n instance of one of the first color cameras used in broadcasting in the 1950s, is shown next to the adult female on the correct. Note how information technology compares to one the latest pocket sized cameras (consummate with a video recorder) shown in the insert at the lesser of the photo.
The latter camera, and in fact most of today's video cameras, 
use an imaging chip, such equally the CCD shown on the left. Many cameras have at present moved to a CMOS flake, but at this point the stardom is not that of import.
The virtually common scrap sizes are 1/ii inch and ii/iii inch (the size of the petty box shown nearly the heart of the CCD chip above).
The 1/two inch bit has a diagonal surface distance of eight mm (less than a third of an inch), while the 2/3 inch has a diagonal of 11 mm (less than a half of an inch).
High resolution professional cameras often utilise a larger chip, upwards to the size of a 35mm motion moving picture film frame.
Video Resolution
V ideo resolution is a measure of a video photographic camera's ability of to reproduce fine detail.
The higher the resolution--the more distinct lines in a given space that the camera can discern--the sharper the flick will look. Nosotros'll take a closer look at how this is measured in a moment.
T he standard NTSC broadcast Tv set organisation tin can potentially produce a picture resolution equal to most 400 lines of horizontal resolution. (This is after it goes through the broadcast procedure. What you see in a TV command room is generally much higher.)
CATV, DVD, HDTV, and digital satellite Tv set transmissions get beyond what's mutual in standard commercial broadcasting.
Note that the number of lines of resolution (sharpness) is dissimilar than the total number of horizontal scanning lines, which is 525 or 625 in SDTV.
Iii- to four-hundred lines of resolution equal what viewers with 20-20 vision tin come across when they watch a Tv set screen at a normal viewing distance.
"Normal" in this case translates into a viewing altitude of about eight times the height of the TV picture. And then, if the Tv set screen were forty cm (sixteen inches) high, a so-called 25-inch (64-centimeter) moving-picture show, the normal viewing distance would exist virtually 2 meters (10 feet).
H DTV/DTV, with its significantly higher resolution, makes possible both larger screens and comparatively shut viewing distances. 
A lthough most SDTV sets in homes are capable of only 300-400 lines of resolution, Telly cameras are capable of much higher resolution -- up to i,000 lines or more.
And then this question arises: Why carp with high resolution in cameras with their added costs when the habitation Idiot box gear up tin't reproduce this level of sharpness?
Respond: Every bit in nigh aspects of Television receiver production, the meliorate quality you lot tin start out with the better the quality will exist for the TV viewer--even with all the broadcast-related losses.
Determining Resolution
C harts that contain squares or wedges of lines on a light background tin signal the limits of sharpness. 
Within a particular area of 1 of these resolution charts there are lines that converge. The illustration on the left was taken from the total test pattern prototype shown higher up. (Notation the ruby-red rectangle.)
Numbers such equally 200, 300, etc., appear on the chart next to the corresponding line densities. By exactly filling the camera viewfinder with the resolution chart and observing the point on the chart where the lines appear to blur together and lose definition, nosotros can (in a crude way) establish the limits of resolution.
Loftier-quality standard definition, NTSC cameras can resolve about 900 lines; HDTV/DTV cameras over 1,000 -- well off the chart shown here.
Colour Resolution
T he resolution nosotros've been discussing is based on the sharpness of the black and white (luma or luminance) component of the Boob tube image.
Information technology was discovered early on in the experiments with color TV that the homo eye perceives detail primarily in terms of differences in effulgence and not in terms of color (chroma) information.
When NTSC color goggle box was developed a highly complex system of adding a lower-resolution colour signal to the existing black-and-white signal was devised. Using this organisation, color information can be added to the existing monochrome signal without having to greatly expand the information carrying capacity of the original black-and-white signal.
Minimum Light Levels for Cameras
T elevision cameras require a certain level of light on a scene to produce skillful-quality video. This low-cal level is measured inlux or pes-candles. The latter unit is used in the U.s.a. and lux is used in other countries.
A foot-candle is a measure out of lite intensity from a candle at a distance of 1 foot (under very specific weather condition). The origin of the term "lux" is non known, although it's assumed to refer to lumens (a mensurate of low-cal power) times ten.
Since we'll refer to both lux and human foot-candles throughout these modules, y'all'll demand to know that a human foot-candle is equal to about 10 lux. (Actually it's ten.76, merely ten is generally close enough, and it's much easier to apply in conversions.)
M ost professional video cameras require a light level of about 75 foot-candles (750 lux) to produce the best quality video. Virtually homes and offices exceed this.
Withal, consumer (non-professional) video cameras typically demand a higher level of illumination for the best video.
Westward ith consumer-blazon camcorders you volition notice advertising literature claiming that a particular camera is capable of shooting pictures under less than one lux of light. (The light falling on a bailiwick from a 60-watt light bulb three meters [x feet] away is almost x lux.)
Nevertheless, if y'all take ever tried this with a consumer-type camera, you know that you tin't expect much in the style of impressive video quality.
A lthough an Environmental impact assessment standard is in identify in the United States to specify minimum quality standards for light levels, adherence to this standard is not mandatory.
Since manufacturers know that consumers want cameras that shoot under low light levels, they are reluctant to use the Environmental impact assessment standard and wait inferior to a competitor who is not adhering to the standard.
Suffice it to say, if you lot are in the market for a camera and you don't see the Environmental impact assessment standard specified, you need to check out any low-light level claims.
By just zooming in on the darkest corner of the room and observing details in the darkest areas, you can make a rough comparison of the light sensitivity of different cameras.
A t low light levels the iris of a camera must be wide open (at the lowest f-end number) to allow in the maximum corporeality of light. As the calorie-free level increases in a scene the iris of the lens must be stopped down (inverse to a higher f-stop number) to maintain the same level of exposure on the camera target.
Under depression light conditions video can chop-chop start to await dark with a complete loss of detail in the shadow areas.
To help compensate, professional person cameras accept built-in, multi-position, video gain switches that can dilate the video signal in steps from 3 up to virtually 28 units (generally the units are in decibels or dB'due south).
Just, the greater the video gain boost, the greater the loss in film quality. Specifically, video noise increases and colour clarity diminishes.
S till and movement picture camera operators who are used to working with IE/ISO (film speed) exposure indexes may want to determine the light sensitivity of their video cameras. This information is often not available from photographic camera manufacturers, but can be determined in 
this three-step process.
Night Vision Modules
F or situations that require video under extremely depression light levels, dark vision modules are available that apply electronic lite
multipliers to amplify the light going through a lens. (Annotation photo.)
The most refined of these tin produce articulate video using only the light from stars (a light level of well-nigh 1/100,000 lux).
A t this betoken nosotros'll take up a new topic, and one that volition be continued into the next module.
Camera Mounts and
Handheld Photographic camera Shots
A lthough a tripod may be a hassle to acquit and prepare up, the results can be worth the effort -- especially when displayed on HDTV screens where camera movement on static scenes can brand an audience a bit "seasick."
Hand-holding cameras for a menses of time can likewise get tiring. Later trying to agree a camera steady for some time, the inevitable fatigue translates into progressively less steady shots.
T he traditional exceptions to using a tripod are in news and sports where you must be mobile plenty to follow moving subjects, documentary style production where shots are brief and rapid, and subjective camera shots that simulate what a moving subject is seeing.
T chapeau having been said, in contempo years the interior shots of many dramatic productions are being routinely shot with handheld cameras. For i thing, it saves product setup time, which means money.
T he award-winning pic, Traffic, released in 2001, had handheld shots designed to impart a documentary experience to some of the scenes.
In the action scenes in the 2007 film, The Boune Ultimatum, handheld shots were used to convey periods of full frenzy.
In the hands of a professional director of photography this upshot can work; withal, when less experienced videographers attempt to handhold a camera (especially while zooming, panning and tilting) the event can look amateurish and even make viewers a fleck ��nauseous.
Photographic camera Pan Heads
O north about tripods the pan and tilt head (which attaches the camera to the tripod) is non meant to exist used for smooth panning and tilting while shooting -- just to reposition and lock the camera into position between takes.
And, this may be just too, given the fact that a cut from one scene to some other is faster and generally better than panning, tilting or zooming to new bailiwick affair.
Even so, pans and tilts are usually seen -- especially for following action, for revealing the relationship between objects in a scene, etc. Therefore, many tripods have heads designed to polish out pan and tilt movements.
There are many types, merely the almost-used type is the fluid caput shown here. It provides an adjustable resistance to pans and tilts -- only enough to smooth out the process.
Bean Bags
A unproblematic camera "mountain" 
that works in many situations is the beanbag. The photo on the left shows ane on the door frame of a auto.
The "beans" inside are minor round plastic balls that can assume the shape of the surface the bag sits on. The pinnacle of the bag tin can accommodate to the bottom of a camcorder, providing a degree of camera stability.
When used on accommodating surfaces, bean bags tin can stand for a quick approach to getting shots.
Wireless Camera Modules
A lthough camera operators doing "live" broadcasts from the field used to have to be "hard wired" to a production truck, today's cameras tin can relay the camera'due south point via a RF (radio frequency) transmitter.
One is shown here on the dorsum of a camcorder.
These units are commonly used in laurels programs, assuasive cameras operators to freely roam throughout the isles to get shots of audition members without the problem of abaft and hazardous camera cables.
The photo at the meridian of this folio is from blackmagicdesign.com. Although the camera past itself (behind the lens) is pocket sized, it is capable of professional person quality video. Numerous lenses are bachelor for this camera and the technical specifications exceed those of many large professional video cameras.
In recent years SLR blazon "still" cameras -- primarily Canon and Nikon -- are being used in professional video production.
More than 
Source: https://www.cybercollege.com/tvp017.htm
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