I/R - Infra Red
When a CCTV camera is positioned in a low light or dark area the camera needs to be provided with a light source in order to gain good images. IR cameras work in conjunction with LED’s that are often built into the camera or sometimes separate IR Lamps. Once the light levels drop below a certain level the camera illuminates the areas using the LED’s. The distance of Infra Red you will gain depends on each individual camera and its LED power.
I/R Cut - Infra Red Cut
This means that the camera filters out any Infra Red during the day to avoid distortion. When IR kicks in during the day the colours become distorted and the picture can often be very white. The IR Cut filters out the IR in the daytime and at night if a subject comes close to the camera, the IR Cut filters out the infra red bounce back from the subject. This reduces the white out or ghost effect that can occur and therefore creates better night time imagery.
These work in the same way as Infra Red LEDs but have a wider emitting angle than standard LED’s. Standard LED’s emit IR rays in a narrow angle typically 40-50 degrees, I/R arrays emit rays that reach around 150-180 degrees. This means more of the surveillance area is covered in dark environments.
The 720 stands for the quantity of horizontal television lines and the ‘p’ at the end means ‘progressive scanning’ is being utilised. Progressive scanning means the highest quality display method is used therefore 720p is high quality. The higher the number, the higher the overall quality of image will be.
This means the amount of pixels on the camera window are 1920 pixels horizontally and 1080 pixels vertically. The more horizontal and vertical pixels there are, the better the image.
Mp stands for Mega Pixels. The higher the number of mega pixels the better the ability to see detail therefore the higher the quality of image.
Varifocal refers to the lens and its ability to be adjusted to suit the view angle required. For example, a fixed viewing lens of 3.6mm would give a non adjustable viewing angle of around 80 degrees and a 2.8mm to 12mm lens would give an adjustable viewing angle of between 90 degrees and 30 degrees. A 90 degree angle gets more width into the shot and therefore covers more viewing area however if you look at the furthest point the detail can be smaller than you require. A 30 degree angle creates a more narrow shot however if you look at the furthest point the detail is closer and more detailed. In most CCTV systems, varifocal lens are the preferred choice as the angles required can differ drastically on each camera location and can therefore be set up to suit.
PTZ stands for Pan Tilt Zoom. This is a camera with the ability to move, in particular to pan and rotate to a set degree of rotation (usually 360 degrees or a full circle). The camera is also able to to tilt down and up usually 90-180 degrees and then to zoom to get a closer picture.
Optical and Digital Zoom
Digital Zoom is a zooming process that makes the image larger and closer but does not maintain the picture quality. Optical zoom is a zooming process that makes the image larger and closer whilst maintaining the picture quality and detail therefore optical zooming is a very worthwhile feature if you wish to look closer at objects further away.
CMOS is short for Complementary Metal Oxide Semiconductor. It is newer technology than CCD and utilises less power. It is smaller in size than CCD sensors but reproduces lower quality images. CMOS cameras are usually less expensive than CCD Cameras depending on the other components involved.
Lux is the number that represents the intensity of light. The lower the LUX number, the less light is required to reproduce a quality image. Black and white cameras generally have less LUX than colour cameras and therefore produce better pictures in dimmer environments.
Analogue HD Cameras
HD stands for High Definition and are cameras with higher resolutions up to Full HD (1920 x 1080p). There are analogue and IP HD Cameras. Analogue HD Cameras reach 720p and 960p where IP Cameras start from 720p through to 1080p full HD and even higher if you want to reduce the frame rate.
This is the number of frames per second which is often referred to as fps. Real time is 25 frames per second and will therefore produce smooth video. 12.5 frames per second is half the speed of reality and creates jerky video.
IP stands for Internet Protocol and is a type of CCTV camera that sends and receives data via a network and the internet. There are two types of IP Cameras. Centralised IP Cameras require a central Network Video Recorder and decentralised IP Cameras which have a built in recording function and therefore record direct to local storage media. IP Cameras generally have higher quality imagery but will require larger storage spaces to record for lengthy periods of time.
ONVIF stands for Open Network Video Interface. If IP Cameras and NVR’s are made to ONVIF protocol it means that regardless of the brand of camera and NVR they should be compatible with each other.
OSD stands for On Screen Display and is a menu displayed on screen that allows you to change camera settings.
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