IP surveillance cameras are ubiquitous today. Everyone who sets foot out his door is well aware that somewhere, sometime on his journey he will enter into and out of several cameras’ fields of view.
Since very few everyday security cameras are covert, one has only to look several feet up at buildings, light poles, retail store ceilings to see this is true. There is a reason for this – the sight of a surveillance camera can be beneficial in deterring crime.
But there are also cameras capable of surveying an area, sight unseen, from, literally, miles away. These surveillance cameras fall under the heading, long-range cameras.
How Long is Long Range?
There are long-range IR PTZ cameras and there are thermal vision long-range cameras. Before we can define how far a camera can see, or which technology is most appropriate, it is necessary to know what the user means by “see” , and when she wants to see it.
Does she want to detect, recognize, or identify?
- To detect is to discover or ascertain the presence of a person or object.
- To recognize is to perceive from knowledge or characteristics.
- To identify is to ascertain or determine the origin, nature, or characteristics of a person or object.
If a user’s objective is to detect that a border has been breached or recognize the presence of a tank or group of people, thermal imaging long-range cameras are sufficient. Some models can actually pick up a man-sized target more than 11 miles away or a vehicle -sized object 13+ miles distant.
Although thermal imaging can work at longer distances than IR and cut through fog, mist, and smoke, IR comes out ahead when it comes to resolution and grayscale, so if the user wants to see faces, or even read license plates in the dark, the long-range IR PTZ camera is the better choice.
How Do IR PTZ Cameras Work?
The answer lies in the lens….and the image sensor….and the laser IR illumination system.
Long Range Lens
In understanding how a long-range lens works, it helps to first consider a standard telephoto lens. Also known as a long lens, a telephoto lens is built with a special-construct that gives it a longer focal length than the lens itself. These focal lengths generally range from 85 mm to over 800 mm.
Long-range cameras use an IR corrected motorized zoom lens making it capable of seeing the actions of a person 2.4 miles away in daylight and 0.9 miles away at night
Long Range IR PTZ cameras use 1/2-inch light CCD image sensors that enhance both day and night light, enabling them to process images in virtually any environment.
Laser IR Illumination System
Long-range cameras operate in the absence of light by using a zoom laser IR diode capable of providing illumination up to distances of 2.5 miles.
Remote installations and facilities that are vital to the security of our country install long-range cameras, both thermal and IR, to guard against terrorists and trespassers. Such applications include
- Oil Platforms
- Oil and Gas Pipelines
- Power plants
Our Armed Forces in Iraq and Afghanistan also use IR and thermal cameras in deserts and mountainous regions to detect snipers hiding in the rugged terrain.