CCTV camera security terms and definitions of camera lens, light levels and other specifications are provided in this glossary.

Aperture
In CCTV optics, the aperture is the diameter of the lens that controls the amount of light reaching the image sensor. It is shown by an f-number. Larger aperture lenses have smaller f-numbers. For instance, a lens with an f-number of 1.2 will allow more light to reach the sensor than a lens with an f-number of 2.0 thus producing a brighter image.

Auto Iris Lens
An automatic iris lens is a lens with a motorized iris that automatically adjusts to only allow a specific amount of light to reach the image sensor. When there is little light, the iris will open to let more light in. When there is too much light, the iris will close to reduce the amount of light let in. Auto iris lenses are primarily used in applications where light levels vary and it would be impracticable to manually adjust the lens. Automatic iris lenses are generally more efficient than the electronic shutter sence they actually control the amount of light reaching the sensor as opposed to simply adjusting shutter speed.

Back Light Correction (BLC)
Many security cameras include a BLC circuit. This circuit is used to help correct an image with more light behind the subject being viewed. Without backlight compensation, the subject appears dark with little detail. Using the backlight compensation will reduce the brightness of the light to allow the subject to appear brighter and bring out the details.

CCTV Camera Format
Refers to the size of the imaging sensor. Common formats are 1/4", 1/2", 1/3", 2/3" and 1". The size of the sensor directly affects the field of view obtained. When using the same size lens on different format sensors,different viewing areas are obtained. For example, using a 6mm lens on a 1/3" sensor will give you a 37 degree field of view. Using the same lens on a 1/2" sensor will increase the field of view to 56 degrees and 74 degrees on a 2/3" sensor. It is important to make sure you have a lens that was designed for your camera's format. The lens must be designed for at least the size of your sensor. For instance, you can use a 1" format lens on a 1/3" camera, but you cannot use a 1/3" lens on a 1" camera.

C Mount CCTV Camera Lens
An industry standard for lens mounting. The C-mount has a thread with a 1 " diameter and 32 threads per inch. The distance from the lens mounting surface to the sensor surface is o.69" (17.526mm). It is not possible to mount a C-mount lens onto a CS-mount camera even with the use of adapters.

CS Mount CCTV Camera Lens
An industry standard for lens mounting. The CS-mount has a thread with a 1" diameter and 32 threads per inch. The distance from the lens mounting surface to the sensor surface is 0.492" (12.5mm). It is possible to use a CS-mount lens on a C-mount camera using a CS adapter ring.

Composite
A single video signal that contains luminance, color, and synchronization information. The American standard NTSC (525 lines, 30 frames per second) and European standard PAL (625 lines, 25 frames per second) are examples of composite video.

Depth of Field
For a lens, the area along the line of sight in which objects are in focus. Depth of field is measured from the distance behind an object to the distance in front of the object when the viewing lens shows the object to be in focus. Depth of field increases with smaller lens aperture (higher f-numbers) shorter focal lengths, and greater distances from the lens.

Digital Recording
The newest form of archiving and reviewing. Digital recorders are slowly replacing time lapse recorders as the number one storage media. Digital recording takes advantage of the speed and reliability of PC hard drives and other computer storage devices such as high speed DAT media, CD-ROM and compact flash media. Storage using these devices virtually eliminates video degredation. Digital recording also opens up almost limitless remote viewing possibilities using standard transmission modes such as LAN, WAN, ISDN, phoneline and the internet. Increased file security also eliminates image manipulation so you can be certain the video is authentic and unaltered.

CCTV Camera Focal Length
The distance from the lens to the surface of the viewing sensor when the subject is focused. (Expressed in millimeters) Shorter focal lengths give a wider field of view. Longer focal lengths give a narrower (telephoto) view.

Hole-Accumulation Diode (HAD)
EXview HAD CCD is a trademark of Sony Corporation. The HAD CCD dramatically improves light efficiency by including near infrared light as a basic structure of the sensor. Conventional CCD sensors are sensitive to infrared light but are unable to efficiently gather the charge. Because of this greater efficiency, HAD CCD sensors achieve sensitivities approximately 4 times that of a conventional CCD.

Field of View
The width, height, or diameter of a displayed image. This is determined by the lens focal length, imaging sensor size, and the distance to the subject being monitored. Usually expressed in degrees horizontal or vertical.

Infrared Lighting (IR)
The area below the visible spectrum. B&W cameras are very sensitive to infrared light and allow the use of infrared illuminators to enhance poorly lit locations without alerting subjects during surveillance. Color cameras are also sensitive to infrared light, but require an infrared filter to filter out the red light to keep the image colors looking natural.

Field
One of the two equal parts into which a television frame is divided is an interlaced system of scanning. There are 60 fields per second in the NTSC system. The NTSC field contains 262 1/2 horizontal lines. Adjacent lines in a TV picture are located in alternate fields. (525 lines total)

Lux
A unit measuring the intensity of light. Full moon light is about 0.1 lux whereas full daylight is about 10,000 lux. Most color cameras can produce decent images during deep twilight. Most black and white cameras need full moon light (0.1 lux). With the new HAD and Super HAD CCD cameras, the only light you need is starlight on a dark night. (about 0.0003 lux)

Monochrome
Black and white and all shades of grey. In a monochrome video signal, this controls the brightness of each pixel. Since there is no color, the brightness determines what shade of grey the pixel needs to be. In a color signal, monochrome controls the brightness of the pixel, whether it is color or not.

Multiplexer with multirecord capability
Using a multiplexer (as opposed to a quad processor), it is possible to record multiple cameras full screen with one VCR. Since every video signal is comprised of 30 frames per second, you can divide these frames among each camera. A multiplexer will send a camera's video signal to the VCR at a consistent rate. In our example we have 8 cameras connected to a multiplexer. Each camera is recorded evenly between 30 frames. In other words, each camera is recorded for a single frame every 8 frames or every 0.266 seconds. So when the video is played back, each camera appears as though it was recorded on it's own time lapse recorder at 3.75 frames per second. The main advantage to multirecording is the use of a single VCR for multiple cameras.... thereby reducing costs dramatically.

Quad Processor
The most basic of the multi-camera processor is the quad. It displays 4 cameras at a time on one screen. With the new digital technology you can record and view more than one camera simultaneously on one screen.

CCTV Camera Super HAD
The Super HAD CCD is a version of Sony's high performance HAD with improved sensitivity through the use of efficient on-chip microlenses. The Super HAD optimizes the shape of the on-chip lenses which minimizes the ineffective area between the lenses on each pixel, thereby, minimizes lost light and improves the overall sensitivity per pixel.

Resolution
The amount of resolvable detail in a picture, or the maximum number of pixels that can be distinguished either horizontally or vertically. Horizontal resolution is expressed as the number of distinct vertical lines that can be seen at a distance equal to the picture height. Vertical resolution is expressed as the number of horizontal lines that can be seen in the picture.

Super Dynamic II
This technology lets you capture richly detailed video in scenes with extremely bright and dark areas. This is accomplished with the double speed CCD that actually captures two images at different exposures. It then combines the two into one video signal that shows detail in both bright and dark areas. Compared with a regular CCD, a Super Dynamic II chip gives 64 times the dynamic range.

White Balance
Color cameras only. Different lighting sources provide different color temperatures. The white balance helps correct these differences by adjusting the color processing to bring the color temperature to a fixed level. Without the balancing feature, due to the CCD's poor adaptability, some colors would appear different (green instead of white in sunlight).

Wavelength
The length of an electromagnetic energy wave as measured from one point on the wave to the next corresponding point on the wave. Usually measured from peak to peak. The wavelength determines the characteristics of the wave and determines the color of light if it is within the visible spectrum. The most common units for measuring wavelengths is the nanometer (one billionth of a micron), micron, millimeter and Angstrom.

Zoom/Varifocal Lens
A lens with an adjustable focal length. Varifocal lenses require focusing adjustments whenever the the focal length is changed. Zoom lenses are described by magnification power according to the difference between the longest and the shortest focal lengths. A 5mm to 50mm zoom lens has a magnification power of 10X. Also, a 10mm to 100mm zoom lens has a magnification power of 10X. Many different varieties of zoom/varifocal lenses are available including both manual and motorized versions.

Network Video:
Network video is video that is transmitted over and is stored on a computer network. The network the video travels on can be a local area network (LAN), wide area network (WAN) or the Internet. No matter what type of network the video travels on, the basics of network video are the same.

Network video utilizes cameras or devices with Ethernet outputs that send video over a computer network or the Internet. The video is broadcast on the network, where it can be received by multiple viewing and image management/storage devices.

The Internet uses a communications protocol called TCP/IP (trnsmission control protocol/Internet protocol) This protocol is also used on most modern computer networks. TCP/IP allows multiple devices on a network to communicate with each other and share resources.

The key to TCP/IP is the IP address. Each device on a TCP/IP network is assigned an IP address,consisting of four sets of numbers from 0 to 255 seperated by periods, identifies the device on the network. This identification allows information to be sent over the network by the device. it also allows information to be received by the device.

Network Video Devices Include Cameras, Transmitters and Recorders:
Network video devices have an IP address so they can access the network, and they have the ability to send video over the network. The devices may generate their own video via a built-in imager, or they may accept video from other sources and translate it for use on the network.
A network camera, also called an IP camera, is basically a CCTV camera with a built-in Ethernet connection that allows video to be broadcast over a TCP/IP network.

Network Cameras:
A network transmitter, also called a video server, accepts video inputs from external devices and converts them to to be broadcast over the network. Network transmitters can accept one or more video inputs at the same time. Depending on the configuration of the network transmitter, the cameras may be broadcast as a single IP address (multiple cameras in split screen) or as multiple IP addresses (individual cameras on individual addresses).

DVR with Ethernet Connection:
A DVR with an Ethernet connection can broadcast video over a network. The transmission is the same as a network transmitter., and multiple cameras are usually broadcast as a single IP address. The difference is the DVR typically allows the person viewing the remote video to control the cameras being viewed. The DVR may also allow viewing of recorded video as well as live video.

Network Video Recorder (NVR):
Network video recorder (NVRs) are to network video transmitters and cameras what DVRs are to conventional CCTV systems. An NVR can receive multiple video signals from multiple cameras over a network connection and record them on a hard drive. The video comes in the NVR's Ethernet connection to the network or Internet. NVRs are available as complete units and as software only.

Hybrid DVR Video Recorder (HVR):
The Hybrid Video Recorder (HVR) is capable of recording video from conventional cameras connected to the DVR and network cameras connected to the network. These systems allow conventional and network cameras to co-exist on the same recording device.

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Last modified on Monday, June 6, 2011