Modern cameras and lenses are generally CS mount. With CS mount cameras, both types of lenses can be used, but the C mount lens requires a 5mm ring to be fitted between the camera and lens to achieve a focused image. With C mount cameras it is not possible to use CS mount lenses

Cable compensated amplifier:
High frequency video signals are attenuated when transmitted through cables. A cable compensated amplifier boosts the high frequency signals depending upon the cable distance. This ensures minimum video loss.

Cable core:
is the central part of the cable which actually carries the video , control or power signals. It can be made up of a single conductor ( solid core) or a number of electrical wires.

Cable jacket:
is the outer protective coating which covers the core of the cable.

Cable tray:
is a long tray installed in many sites which allows cables to be economically laid out.

Camera:
is an electronic device which converts light into an electrical signal.

Camera controller:
controls the different functions of the pan tilt head and the zoom lens. It is also known as the PTZ controller.

Candela:
a new unit which replaces the candle and is a measurement of luminous intensity

Cathode ray tube (CRT):
is a tube in the monitor containing a heated cathode which emits a beam of electrons focused on a phosphor coated surface. The surface glows depending upon the intensity of the beam. The deflection circuitry in the tube controls the movement of the beam.

CCD Charge Coupled Device:
is a solid state device in a camera that converts light falling on it into an electrical signal.

CCD iris:
is a feature in modern CCD cameras by which the iris function is performed by the CCD chip itself. This eliminates the need for an auto iris lens. The CCD iris can handle minor light fluctuations only and therefore is not recommended for most outdoor applications.

CCIR International Radio Consultative Committee:
recommends a format of 625 lines per frame and a transmission speed of 25 frames per second.

Celsius:
is the metric unit for measuring temperature. In this scale, the boiling point of water is 100 deg. In the USA, the unit used to measure temperature is Fahrenheit.

Channel separation:
When signals are multiplexed at different frequencies for transmission, then the separation between these frequencies is called channel separation. Poor separation can lead to cross talk.

Chromatic aberration:
is an error in lenses which causes the focal point to be scattered. This occurs because different wavelengths of light bend differently through a lens. A combination of lenses are required to minimise this error.

Chrominance signal:
is that part of the video signal which contains the colour information. In S-VHS, this signal is transmitted along a separate cable. In a composite video signal, the chrominance signal is multiplexed at a higher frequency and sent along the same cable.

Colour stripe filter:
is a type of filter placed in front of a colour CCD chip. It breaks up light into the basic colours - red, green and blue which are then directed to separate pixels in the CCD chip

Common sync generator:
is a device used to synchronise cameras. It generates synchronising pulses that are sent to all cameras connected to it by coaxial cable.

Composite video:
is a standard signal format in CCTV which contains the video signal, the horizontal and vertical sync pulses and the blanking pulses. The sync pulses are 0.3 volts and the video signal is 0.7 volts.

Concave:
is a type of optical lens in which the light rays passing through it are made to diverge by the inward bulge of the glass surface.

Conduit:
is a plastic or metallic tube which is used to conceal, protect or secure cables.

Connector:
a device used to interconnect cables or connect cables to various equipment.

Contrast:
is the difference in the intensity between the black parts and white parts of the picture on the monitor.

Contrast Control:
is a control in the monitor which changes the contrast by increasing or decreasing the amplitude of the video signal.

Covert:
is a mode of CCTV surveillance in which the camera and lens are hidden and cannot be seen.

Convex:
is a type of optical lens in which the light rays passing through it are made to converge by the outward bulge of the glass surface.

Crimping:
is a process of connecting a cable to a connector without screwing or soldering using a special tool. In crimping a BNC connector, the centre pin of the connector is uniformly pressed against the cable core. To ensure a proper connection, a good crimping tool is needed.

Cross talk:
is the noise generated by the interference between adjacent ( in terms of signal frequency) video, audio or data channels in a multiplexed signal.

CS mount:
is a lens mount with 12.5 mm back flange. Back flange is the distance between the lens mounting surface and the CCD chip.

Camera format:

The size of the camera's imaging device (CCD) also affects the angle of view, with the smaller devices creating narrower angles of view when used on the same lens. The format of the lens, however, is irrelevant to the angle of view, it merely needs to project an image which will cover the device, i.e.: the same format of the camera or larger. This also means that 1/3" cameras can utilize the entire range of lenses from 1/3" to 1", with a 1/3" 8mm lens giving the same angle as a 2/3" 8mm lens. The latter combination also provides increased resolution and picture quality as only the center of the lens is being utilized, where the optics can be ground more accurately.