A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Select the first letter of the word to jump to appropriate section
of the Film Glossary.
- A -
-
- Active Video Lines
All video lines not occurring in the horizontal and vertical blacking intervals.-
- AFC
Abbreviation for automatic frequency control,
a circuit built into some
VCRs and TVs to automatically lock onto an incoming channel.
- AFM
Audio frequency modulation is the type of audio recording used on
Beta HiFi and VHS HiFi VCRs. The audio is laid on the
tape by audio
heads located on the video head assembly.
AGC
Abbreviation for automatic gain control. On a TV or VCR, AGC is a
circuit that automatically adjusts the incoming signal
to the proper
levels for display or recording. On a video camera, AGC is a circuit
that automatically adjusts the sensitivity of the pickup tube to render
the most pleasing image.
Alarm Activated VCR
After pressing 'record'', a normal VCR takes
about 20 seconds before
it starts recording usable pictures. With and alarm activated recorder
it can be set so that the tape is ready to start recording in about one
second. The signal to begin recording can be from an alarm or any
other input.
Aperture
The light gathering area of a lens, controlled by the iris.
Aspect Ratio
The ratio of the vertical to the horizontal image size. This is usually 3:4.
Attenuation
This refers to signal loss in a transmission system
Audio S/N Ratio
Signal-To-Noise Ratio is the ratio of pure audio signal versus noise.
Automatic Iris
A lens that adjusts automatically to allow the right
amount of light to
fall on the imaging device. There is a tiny motor and amplifier built in
which receives a control signal from the camera to maintain a
constant one volt peak to peak
(1.0 Vp-p) video level.
- B -
-
- Back Focus
A mechanical adjustment in a camera that moves the
imaging device
relative to the lens to compensate for different focal lengths of lenses.
This is important when a zoom lens is fitted.
Balanced Signal
A video signal is converted to a balanced signal to enable it to be transmitted
along a 'twisted pair' cable. Used in situations where the cabling distance is too great.
Bandwidth
The range of signal frequencies that a piece of audio
or video equipment
can encode or decode; the difference between the limiting frequencies
of a continuous frequency band. Video uses higher frequency that
audio, thus requires a wider bandwidth.
BetaCam & BetaCam SP
BetaCam was first introduced in 1982. It is currently
geared for broadcast use, although there have been some less expensive models destined
more for industrial use. Pictures you will get using a BetaCam system (or other component
format) will generally be markedly superior to those you would get using any of the
preceding formats. Colors in particular come out looking much more vibrant and objects
appear three-dimensional. The superiority of BetaCam shots comes partly from the technical
aspects of the tape format but also in large part because of the use of superior optics
and other camcorder and VTR components (and generally better operators!).
The difference between BetaCam and BetaCam SP, introduced in 1986, is in the tape. Betacam
SP uses a metal tape and is an improvement over BetaCam.
BetaCam cassettes are large. Ninety minute cassettes measures 5.5 by 10 inches (14 by 25
cm). Typically BetaCam field units (camcorders or dockable decks) handle only smaller
cassettes with shorter lengths of tape (30 minutes and less). These smaller cassettes are
4 by 6 inches (10 by 16 cm) in size.
Betamax
Betamax tapes were a format originally introduced by
Sony in the 80's. It was thought to be a better format at the time. However, the Beta vs
VHS wars took place and VHS was the victor. There are still a few Beta fans out there
though and you can still get a Betamax machine if you look around.
- Blooming
Picture distortion caused by a high video level. Blooming results when the
image sensor of the video camera picks up a very bright subject or an area
with high illumination.
- Burst
A component of a television signal that carries color information.-
- Brightness
In color video, the characteristics that makes pictures appear to be most
intense, created by luminosity; also the quality of being filled with light.
- C -
-
- C-Mount
The standard screw mounting for 2/3" and 1" camera lenses. The distance
from the flange surface to the focal point is 17.526mm. A C-Mount lens can- be used on a camera with a CS-Mount by adding adapter ring to reduce
the
- distance to 12.5mm.
CS-Mount
A new generation of lenses designed for 2/3",
1/2" and 1/3" cameras incorporating CS-mounts. The distance from the flange
surface to the focal point is 12.5mm. CS-mount lenses cannot be used on cameras with
C-mount configuration. These lenses are smaller and cheaper than the C-mount equivalents.
CATV
An abbreviated term for Community Antenna Television, now generally
regarded as "cable TV".
CCD
Charged-Couple Device used in some video cameras instead of an image
pickup tube. Light-sensitive microprocessor that converts an image into an
electrical flow. CCDs are not prone to image smear or lag and make light
weight cameras possible.
CCIR
Committee Consulat International Radiotelegraphique. This is a standards
committee of the International Telecommunications Union, who have made
the technical recommendation for European 625 line standard for video signals.
Chroma
Short for chrominance. Chroma is the color component of the video signal.
Clipping
An effect of distortion where the peaks of driven signals are chopped off.
Clipping usually occurs in the amplifier when it is turned up too high, but it
can occur in maladjusted circuits in a VCR or TV set.
Color Burst
The signal, at approximately 3.57MHz in the video
bandwidth, that stores the instantaneous intensity and hue of the color for a particular
spot in the TV image.
Comb Filter
An electric filtering system designed to pass a certain set of frequencies but
reject others.
Composite Video
A picture signal combined with synchronization and (possibly) color
information. Usually called baseband video, or just video.
Control-L
Also referred to as LANC, this is a control protocol found on 8mm and some
VHS decks that provides computer control of unit operation. Units are
connected through a special cable.
Control Track
A linear track, consisting of 30- or 60-Hz pulses, placed on the bottom of
videotape that aids in the proper playback of the video signal.
Convergence
Three colors-red, blue, and green-are used in
television to produce all colors.
These separate scanning beams (one for each color) must strike their targeted phosphors
(screen's internal coating) with precise accuracy. If the beams are out of alignment, then
the image and colors appear muddied.
Crosstalk
A signal from one stereo channel that bleeds into the other. Also, a signal
from a video track on a tape bleeding into the signal on the adjacent track.
CRT
Cathode Ray Tube. The main part of a normal monitor or television.
AKA the screen.
- D -
- Decibel (dB)
A unit of power measurement. A 6 dB rise in signal strength represents a
100-percent increase (or doubling) in power.-
- Demodulate
To remove the carrier signal and leave only baseband audio and video.
Depth of Field
The are in which all objects picked-up by the camera lens appear in focus.
Depth of field depends on subject-to-camera distance, focal length of the
lens, and f-stop.-
- Digital 8
The DIGITAL 8 format is far superior to
HI-8 or 8MM. Sony was the first to introduce this format and has done a great job. It is
backwardly compatible, meaning that the new Digital8 camcorders and VCR's will also play
your 8MM and HI-8 tapes. You do not have to buy special tapes to record in Digital8. A
regular 8MM or HI-8 tape will record up to 60 minutes of digital video and audio. Because
of the design, using regular tapes is not a problem, but it uses twice as much tape. A 2
hour HI-8 or 8MM tape will record 60 minutes when done in the Digital mode. For more
information on Digital8.
- Digital Signal
An analogue signal that has been converted to a digital
form so that it can be processed with less error.
DNR
Dynamic Noise Reduction.
- E -
- EIA
Electronic Industry Association. An industry lobbying group; it collects
statistics and establishes testing standards for many types of home electronics.-
- EIAJ
Electronics Industry Association of Japan. The Japanese equivalent of the EIA.
- F -
- F-Connector
The standard connector used with coaxial cable and the RF inputs/outputs
of most video equipment.-
- Field
One-half of a video field, comprising the odd or even scan lines. There are
60 fields in one second of video.-
- Flagging
Bending at the top of a picture played back by a VCR.- Focal Length
The distance between the secondary principal point in
the lens and the plane of the imaging device. The longer the focal length, the narrower is
the angle of view.
-
Footcandles
(Ft-c) Lumens per square foot; the measurement of the intensity of light on
a camera.-
- Frame
One complete video picture, comprising both odd and even fields. There
are 30 video frames per second.-
Frame Store
An electronic method of capturing and storing a
single frame of video. All slow scan transmitters include a frame store that holds the
picture at the moment of alarm, while the control is being dialed up. When the link is
confirmed, the picture is transmitted
- Gain
The level of amplification of a signal.-
- Gen-Lock
Alignment of the sync generators of one or several sources to main sync
source. Used in multi source camera shoots or editing.
- Helical Scan
The technical name for the way the video heads in a VCR record and play
back picture information. Also used to record and play back stereo HiFi audio.-
- HI-8
HI-8 camcorders record their signal at about 400
lines of resolution, slightly less than Mini DV, but substantially higher than 8mm or
regular VHS formats. Most often, HI-8 camcorders record sound in hi-fi stereo. Slight
quality loss is suffered when copying or editing from HI-8, but a better than average
image is maintained. Tapes from HI-8 camcorders generally must be played using the camera
as the source, which means the user often must connect cables to their television or VCR.
HI-8 tapes can be bought in 30, 60, and 120-minute lengths.-
- Horizontal Resolution
The number of vertical black and white lines that can
be defined, as measured along a horizontal line.
- IR
Abbreviation for infrared.-
- Image Enhancer
Electronic device that smoothes out irregularities in a video signal to
improve picture definition.-
- Impedance
The degrees of resistance that an alternating electrical current (ac)
encounters when passing through a circuit, device, or wire. The
amount of impedance is expressed in ohms.-
- Infrared Light
The wavelength of light produced above the visible part of the spectrum.
- Interlace
Each television frame (30 per second) or individual
picture is comprised of two fields (A and B). These two fields seem to appear at once on
the TV screen, but each field is scanned separately in the picture or image-creation
process. Each field contains 260 lines of picture information. How well these lines are
interlaced determines the resolution of the resulting picture.-
- Internal Sync
The internal generation of sync pulses in a camera using a crystal controlled
oscillator. This is needed on non-mains powered cameras.- Iris
Adjustable lens opening that regulates amount of light entering the camera.
- Line Locked
The sync pulses of cameras are locked to the AC mains frequency.-
- Line Powered
A camera in which the power is supplied along the same
coaxial cable that carries the video signal.-
- Loop Frame Store
The principal is that a series of video frames is
compressed and stored in a continuous loop. This records a certain number of frames and
then records over them again until an alarm signal is received. When this happens it
carries on recording for a dozen frames or so and then stops. This means that frames
before and after the incident are recorded. This eliminates the boring searching through
hours of video tape and concentrates on the period of activity.
- Luminance
The term used to denote the brightness or black-and-white picture of a video image.-
- Lux
A measurement of illumination. The metric equivalent of footcandle.
- Macro-Focus
Some zoom lenses include this feature, which
allows you to get as close as one or two inches to your subject. This is a great feature
for video taping small objects such as coins, stamps, or insects.-
- Macro-Lens
Lens capable of close-up focusing.-
- MII
Introduced in 1986, MII is Panasonic's answer to
Betacam SP. All MII tape is metal. The 90 minute cassette at 4 by 8 inches (11 by 19 cm)
is considerably smaller than the 90 minute Betacam SP cassette. However the dockable decks
take only a small 20 minute cassette (3.6 by 5 inches - 9 by 13 cm). Technically, MII is
equal to or superior to Betacam SP. Panasonic MII field equipment includes several small
dockable decks usable with a variety of camera heads and some excellent portable decks.
Be aware if you get into MII that at some point repairs may become an issue and that few
duplicating facilities or clients are likely to have MII. Therefore you will probably have
to copy your MII programs to another format at some stage.
- Mini DV
Mini DV tapes are the smallest of the video formats.
They take and maintain crystal clear images because of the nature of a digital format.
Editing enthusiasts benefit from Mini DV as well, since copying between two units is done
with no quality loss. That means edited or copied video looks and sounds every bit as good
as the original footage. Mini DV tapes are available in 30, 60 and 63 minute
lengths. You can also have Mini DV tapes transferred to VHS. For more information on
Mini DV.
- Terminating Resistor
A resistor (usually 75 ohms) attached to the end of a cable or to an input
or output on a piece of video equipment. The resistor restores proper system
impedance.-
-
Test Patterns
A test pattern is used to check out video
systems, cameras and control equipment. Several examples can be found Here.-
Time Lapse VCR
- U-Matic
U-Matic also known as 3/4" video tape. The format
was introduced in 1971 but it is still used by some videographers who have been using the
format for a long time. It can produce good quality video and 3/4" decks are still
commonly available in duplicating houses. However, there is little reason for somebody to
persue this format given the technical advantages of some of the other more recent
formats. UMatic has been used by professionals the world round and found mostly in
studios. The format is slowly being replaced with digital equipment such as DV and Mini
DV.
- Underscanning
A technique generally used by some TV and video systems
as a way of ensuring that the complete image is always visible within a display area; the
opposite of overscanning.
- VHS & VHS/C
Abbreviation for video home system, a
VCR format pioneered by JVC. VHS/C and full size VHS record at a slightly lower
resolution than 8MM. Their appeal, or course, is the convenience of easy playback. The
large VHS camcorders are almost a thing of the past at this point. There are still a few
models available, but their substantial size and weight make them a difficult sell against
smaller camcorders. VHS/C compact models, on the other hand, remain a popular choice,
offering many of the same key features as 8MM camcorders, at an equally affordable price.
- Video Motion Detector
A method of detecting movement in the view of the
camera by the electronic analysis of the change in picture contrast.
- VU
Volume Unit is measured by sound-level meter. VU meters
are usually
marked from -20 to +5 Vus. O Represents the loudest level before
distortion occurs.
- White Balance
Assures the correct balance of red, green, and blue.
Because these
colors are used to create all other colors in television, white balancing a
camera enables you to bring the colors in line for the existing lighting
conditions. Also refers to a camera control that accurately sets light levels
on a white surface.-
- Wide Angle
The wide-angle position of a lens enables the lens to
capture a wider area
of view. Be careful when video taping people with a wide-angle lens at close
range.
- Y/C Video
See S-Video
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