Glossary of Terms – Part 2 (C-F)

May 19th 2008
Tags: Glossary

Glossary of Terms – Part 2 (C-F)

CCD – Charge coupled device, a flat thin wafer that is light sensitive and forms the imaging device of most modern cameras. Size is measured diagonally and can be 1/4″, 1/3″, 1/2″, 2/3″. There are two types, frame transfer and interline transfer.

Chroma Bust – The reference signal includes in the video signal after the horizontal sync pulse. This enables a color monitor to lock on to a color composite video signal.

Chrominance – The part of a color video signal that carries the color information.

Cladding – The outer most region of an optical cable, less dense than the central core. Acts as an optical barrier to prevent transmitted light leaking away from the core.

Composite Video – The complete video signal comprising the sync and video information. The sync pulse should be 0.3 volts and the video signal should be 0.7 volts.

Core – Optical fiber cable is manufactured from high density silica glass. Core is the central region of an optical fiber through which signal carrying infrared is transmitted.

CS – Mount – A new generation of lenses designed for 2/3″, 1/2″, 1/3″ and 1/4″ 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 most compact and cheaper than the C-Mount equivalence.

Depth of Field – The proportion of field of view that is in correct focus. The depth of field in focus decreases when : The focal length is longer, she number is smaller, or the object distance is shorter.

Desktop Switcher – A device for switching the video signal from several cameras to one or more monitors.

Digital Signal – An analogue signal that has been converted to a digital form so that it can be processed by a micro processor e.g Computer/software.

EIA – The American 525 line standard for the video signal.

F stop – This is the ratio of the focal length to the effective diameter of the lens (f/A). It is not the measure of the efficiency or the transmission value of the lens. The smaller the ‘f’ number the more light is passed.

FC – Foot Candles, used in some USA specification to define sensitivity. 10ft is approx. 1 lux.

Fiber optic – A very efficient method of transmitting video and telemetry signals over very long distances using fiber optic cable. Signals can be multiplexed and sent along a single fiber.

Field of View – The relationship between the angle of view and the distance of the object from the lens.

Field – 1/2 of a frame consisting of 312 1/2 lines. 50 fields are created every second.

Flange Back length – The distance from the back flange of the lens to the sensor face. This is 17.526mm for C-Mount and 12.5mm for CS-Mount lenses.

Focal Length – The distance between the secondary principle point in the lens and the plane of the imaging device, the longer the focal length, the narrower is the angle of view.

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 she control is dialed up. When the link is confirmed, the picture is transmitted.

Frame Transfer – A type of CCD imaging device in which the entire matrix of pixels is read into storage before being processed by the electronics of the camera.

Frame – The combination of two interlaced fields, 25 frames are created every second (real time).

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