F-number: The f-number indicates the brightness of the image formed by the lens, controlled by the iris. A smaller f-number allows a brighter image.

F-stop: A term used to indicate the speed of a lens. The smaller the f-number, the larger the amount of light passing through the lens.

Facial Capture: In order to obtain facial capture surveillance for positive identification purposes, cameras should be mounted at vertical height conducive for facial capture (for example, in light switches). Lenses selected should produce identification level imaging and no less than 120% vertical image of the person.

Field: 60 fields are transmitted every second and one half of a frame, consisting of either the odd or the even numbered lines..

Flange back: The distance from the flange of the lens (beginning of the lens mount) to the focal plane. C-mount lenses have a flange back distance of 17.526mm vs. 12.5mm for CS-mount.

Focal length: The focal length determines the size of the image and the angle of the field of view seen by the camera through the lens. The focal length is the distance from the center of the lens to a plane at which point a sharp image of an object viewed at an infinite distance from the camera is produced. That is the distance from the center of the lens to the pickup device.

Foot-candle: It is the light intensity (illumination) of a surface one foot distant from a source of one candela. It is equal to one lumen per square foot. (1FC = 1 lm ft2). The foot-candle is the unit used to measure incident light.

Frame: The total area of the picture which is scanned while the picture signal is not blanked.

Full Duplex: The simultaneous data transmission in both directions of a signal path

Gen-lock: A method used to synchronize one or more cameras by external means such as: composite video, composite sync, horizontal or vertical sync. Old stuff…

Ghost: A shadowy or weak image in the received picture, offset either to the right or to the left of the primary image. It is the result of transmission conditions where secondary signals are created and received earlier or later than the primary signal. Weak video signals from the camera.

Ground: An electrical connection point that is common to a metal chassis, a terminal, or a ground bus that is grounded

Ground Loop: Caused by different earth potentials in a system. In other words, one of them or both are not grounded properly. It sometimes affects video pictures in the form of a black shadow bar across the screen or as poor video at top corner of a picture.

H.264: The latest mpeg4 Part 10 codec is H.264 which provides better compression of video images together with a range of features supporting high-quality, low-bitrate streaming video. The latest and greatest in video compression for CCTV as of 7/2006.

Horizontal blanking: The blanking signal that is provided at the end of each scanning line of the video signal

Horizontal (hum) bars: Horizontal bars, alternately black and white, which extend over the entire picture. They are known as venetian-blinds. They may be stationary or move up or down. They are often caused by poor wiring and AC power (60 Hertz) interfering with the video signal.

Horizontal resolution: The maximum number of individual picture elements that can be distinguished in a single scanning line.

I.R. (Infrared): A range of frequencies lower than visible red light used for covert surveillance or as a low cost wireless video link. An Infrared can view at “No-Light” conditions by illuminating the IR LEDs that surround the camera lens.

IP Address (Static and DHCP): Identifies a particular computer on a network to other computers. An IP address is similar to your home address. In a neighborhood, each house has a unique address; on a network each computer must have a unique address. There are two types of IP Addresses - static and DHCP. A Static address is where someone physically connects to a computer and defines the IP address for that computer. A static address does not change unless someone physically changes it. DHCP or a Dynamic address is dynamically assigned from a server that contains a pool of addresses. The server leases the computer one of the available addresses for a specified amount of time. Once the specified time has expired, the computer renews the lease or requests a new IP address.

Image size: Reference to the size of an image formed by the lens onto the camera pickup device. The current standards are: 1", 2/3", 1/2" and 1/3" measured diagonally. 1/3” is most common