Matakuliah
Tahun
: O0382 – Dasar-dasar Produksi Siaran Televisi
: 2010
THE TELEVISION CAMERA (2)
Pertemuan 4
Electronic Characteristics (1/8)
Electronic Characteristics
There are common electronic characteristics to all television cameras:
(1) aspect ratio, (2) resolution, (3) frame rate, (4) light sensitivity and
operating light level, (5) gain, (6) video noise and signal-to-noise ratio,
(7) image blur and electronic shutter, (8) smear and moiré, (9) contrast,
(10) shading, (11) white balance.
Aspect ratio
As explained previously, the most noticeable changes from traditional
4x3 aspect ratio into digital HDTV 16x9 aspect ratio will affect the output
of picture quality or the image resolution.
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Electronic Characteristics (2/8)
Resolution
Refers to measuring detail in the picture and is the major factor that
distinguishes standard television from HDTV pictures. The quality of
television is determined by the degree of resolution of the video it
produces.
The picture resolution a camera can produce depends on: (1) the quality
of the lens, (2) the number of pixels of the CCD, and (3) the general
signal processing. A camera with a single CCD produced by necessity
lower-resolution pictures than the three-chips cameras.
The resolution of the picture seen on TV depends on the videotape
recording system, the transmission system, and of course the television
set. In print, resolution is measured in dpi (dot/ pixels per inch). CCDs are
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usually measured by the total number of pixels.
Electronic Characteristics (3/8)
Frame rate
Refers to the number of complete video frames the video system
produces each second.
The frame rate is important not only for specifying the quality pictures the
camera produces but also for the compatibility of the camera with the
utilized recording system.
The standard NTSC television scans 30 frames per second (fps). The
480p and 720p scanning systems normally have a frame rate of 60 fps
but possible to have variable frames – especially if used for electronic
cinema productions.
The standard 1080i HDTV system has a frame rate of 60 fps.
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Electronic Characteristics (4/8)
Light sensitivity and operating light level
Light is used to produce a video signal when the camera imaging
device is converting light into electricity, and the light requirement depends
on the light sensitivity of the imaging device.
The minimum operating light level under which cameras perform
adequately is determined by how much light the camera lens admits and
how much the video signal can be boosted electronically before the picture
begins to deteriorate.
Gain
Gain is when a camera can produce pictures in extremely low light
levels because it has the ability to boost the video signal electronically. In
studio cameras, the gain is adjusted through the CCU. In ENG/ EFP
cameras, it is controlled by a gain control switch.
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Electronic Characteristics (5/8)
Video noise and signal-to-noise ratio
The word ‘noise’ refers to the audio field and applied to unwanted
interference in video.
The ‘noisy’ pictures can be recognized by the amount of white or
colored vibrating spots or artifacts that appear throughout an image and
cause it to become less distinct.
If the picture signal is strong (mainly because the imaging device
receives adequate light), it will cover up the snow and the S/N ratio is
desirable. (S/N ratio is signal-to-noise ratio – a relationship between
signal and noise).
If the picture signal is strong then the signal is high (strong
picture information) relative to the noise (picture interference) under
normal operating conditions.
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Electronic Characteristics (6/8)
Image blur and electronic shutter
The image blur has become one of negative aspects of CCD
imaging device. In order to avoid this blur, the CCD cameras are
equipped with electronic shutter. Electronic shutter will control the amount
of time that light is received by the chip. The slower the shutter speed, the
longer the pixel of the CCD imaging surface are charged with the light of
the object and the more the object will blur.
Smear and moiré
Smears show up adjacent to highlights as dim bands that weave
from the top of the picture to the bottom. Digital cameras with high-quality
CCDs are practically smear-free.
Moiré interference shows up in the picture as vibrating patterns of
rainbow colors.
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Electronic Characteristics (7/8)
Contrast
Contrast is expressed in ratio. Contrast is the relatively limited range
between the brightest and darkest picture areas the video camera can
reproduce.
The normal contrast ratio is 40:1 or 50:1 which means that the brightest
picture area can be only forty or fifty times brighter than the darkest one
for optimal picture. If a scene exceeds a camera’s contrast range,
however, either the video operator or automated circuits in the camera
will adjust the picture so that it does fall within the contrast tolerance of
the pickup device.
Shading
An activity when the video operator adjusts the picture to optimal
contrast range.
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Electronic Characteristics (8/8)
White balance
The compensation conducted by the camera when the camera
compensates for the reddish or bluish light to pretend that the camera
is dealing with perfectly white light.
In the studio, the white balancing is usually conducted by video operator
who adjusts the RGB channels at the camera control unit. When
operating a studio camera, you will be asked by the VO to zoom in on
the white-balance card in the primary set area and remain on it until the
white balance is accomplished.
How to white balance:
- Focusing on a white card, piece of form core or other white object that
is illuminated by the lighting in which the performance will take place;
- Zoom in the card until it fills the entire screen (view finder);
- Press the white balance button and wait until the view finder display
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indicates a successful white balance, and redo the steps each time you
encounter a different lighting situation.
Operational Characteristics (1/5)
Operational Characteristics
There are less fewer button and switches owned by studio camera
compared to ENG/ EFP camcorder or a consumer camcorder. It is
because the studio camera is remote-controlled by its camera control unit
and it is the VO who works on all buttons during the production for optimal
picture quality.
On the other hand, the ENG/ EFP cameras and consumer camcorders are
self contained: have all switches and buttons on the camera and the users
can ready the camera and keep the camera operational during the entire
shoot. Furthermore, the automatic control ENG/ EFP cameras and
consumer camcorders make keeping the camera at optimal levels
relatively easy under normal circumstances.
This section will focus on the major operational items and controls of
studio cameras: (1) power supply, (2) camera cable, (3) connectors, (4)
filter wheel, (5) viewfinder, (6) tally light, (7) intercom.
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Operational Characteristics (2/5)
Power supply
All studio cameras receive power from a DC (direct current) power supply
which is supplied through the camera cable.
Camera cable
Camera cables differ in how they carry the various electronic signals to
and from the camera. The 3 (three) characteristics of camera cables:
Multi-core cables: contain a great number of thin wires with the most
limited reach (up to 2,000 feet or about 600 meters), can carry a great
amount of information without any adapters;
The triaxial (triax) cables: have one central wire surrounded by two
concentric shields, can reach maximum of 5,000 feet (1,500 meters);
The fiber-optic cables: contain thin, flexible, glass strands instead of
wires, can reach 2 miles (up to 3,000 meters) both triax and fiber-optic are
thinner and considerably lighter than multi-core and need adapters.
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Operational Characteristics (3/5)
Connectors
When using studio cameras in the field, please carefully check if
the cable connectors fit the jacks of the remote truck. Simple coaxial video
lines all have BNC connectors and multi-core cables come in various
configurations which are usually expressed in the number of pins at the
cable end.
Filter wheel
It is located between the lens and beam splitter. It normally holds
two neutral density filters (NDS), referred to as ND-1 and ND2 and some
color-correction filters.
The NDs reduce the amount of light transmitted to the imaging
device without affecting the color of the scene and these are used when
shooting in bright sunlight.
As for color-correction filters, they compensate for the relative
bluishness of outdoor and fluorescent light and relative reddishness of 13
indoor and candlelight.
Operational Characteristics (4/5)
Viewfinder
Viewfinder is a small television set that shows the picture the camera is
getting. The characteristics of viewfinders are as follows:
 In studio cameras, they are usually in 5- or 7- inch and can be swiveled
and tilted;
 Mostly monochrome (even in HDTV cameras) that means only can see
black and white picture of the scene;
 Also act as a small information center that indicates the following
items and conditions:
a. center maker: that shows the exact center of the screen;
b. safe title area: a rectangle in the viewfinder within which all essential
picture information should be kept;
c. Electronic set up: that includes a variety of control functions such as
electronic gain, optimal video levels, electronic shutter.
d. Lens extenders: the magnifying devices that extend the telephoto
power of a lens;
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e. Multiple views: this allows to see pictures and the special effects.
Operational Characteristics (5/5)
Tally light
A big red light on top of studio camera that signals which of the two or
more cameras is on the air.
This tally light may function:
 to assist the talent to indicate the correct camera;
 to inform the camera operator when the camera is on;
 to acknowledge that two cameras are used simultaneously for a splitscreen effect or for a superimposition;
 when off, tally light may help the camera operator to position the
studio camera.
Intercom
Intercommunication is significant for multi-camera production for the
director and technical director to be able to coordinate. There usually
at least two channels for intercom: (1) for the production crew, (2) for
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the technical crew.
Operational Items (1/3)
Operational Items: ENG/ EFP Cameras and Camcorders
The following explanations are descriptions of the operational items the
functions of field cameras.
Power supply
 Most professional camcorders are powered by 13- or 14 volt battery;
 Consumer camcorders have lower-voltage batteries;
 Substitute power supplies are AC current and car batteries;
 Most batteries can supply continuous power for up to two hours before
recharging;
 When operating professional camcorders use digital battery;
 To avoid the risk of having a camera stop working right in the middle of
a shoot, always charge the battery well before the period indicated by
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the manufacturer’s charge rating is up.
Operational Items (2/3)
Camera cable
Camera cable is used to connect the camera to videotape recorder
or remote control, or to some other external equipments like monitor feeds,
audio recorders, etc.
Connectors
Connectors used to connect camera with receptacle: BNC
connectors for video coaxial cables, XLR or RCA phono plugs for audio
cables, consumer equipment usually uses RCA phono for video cables
and mini plugs for audio.
Exchangeable lenses
Most professional ENG/ EFP cameras use zoom lens that allow to
have optimal zoom range.
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Operational Items (3/3)
Filter wheel
Filter wheel contains at least 2 (two) NDs and a variety of colorcorrection filters.
Viewfinder
Most studio and field camera viewfinders will include the indicators
like: (1) tally light, (2) VTR record, (3) End-of tape warning, (4) the white
balance, (5) battery status, (6) maximum and minimum light levels, (7) gain,
(8) optical filter positions, (9) playback.
Operational Controls: ENG/ EFP Cameras and Camcorders
Since Eng/ EFP cameras represent not only camera head but also
the entire of camera chain (CCU, power supply, and sync generator), then
the cameras have switches and knobs more sophisticated than the studio
cameras: (1) power switch, (2) standby switch, (3) the gain control, (4) white
balance, (5) filter wheel, (6) the VTR, (7) the shutter speed, (8) the camera/
bars selection, (9) the audio level, (10) sound volume and audio monitor
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control, (11) VTR controls.