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Seeing in the Dark – Low Light vs Night Vision

When it comes to CCTV systems the inevitable requirement will always arise for the cameras to be able to see in the dark. Well this is definitely possible and it really comes down to the choice in camera of which there are 2, Low Light or Night vision. Both technologies have their advantages, and likewise disadvantages. Let's take a quick look at both.

Low Light.

The low light CCTV camera comes in 2 forms, either the traditional body cameras that need to be placed in a housing if going outdoors, or one of the more modern Vandal Resistant Domes which can be internal or external with no additional housing. Both work the same way utilising any ambient light at low light levels without the need for any built in IR (infra red) illumination. These are usually the preferred choice for low light environments such as Pubs and Clubs, or city and town centres when there is an abundance of ambient street lamps and shop lighting at night. However they also have a much more useful function when the question comes up of capturing vehicle number plates.  As this technology does not use its own IR illumination it will not suffer from IR bounce back, providing a clear image rather than a reflective white haze in place of the number plate. The one big disadvantage however that if the area you are trying to monitor is in complete darkness then you really won't see much at all.

Night Vision
As the name of the security camera suggests this technology allow the user to see at night with the use of its own built in Infra Red (IR) illumination. These security cameras can see different distances depending on the quantity and intensity of the IR bulbs used, this cam be from as little as 5 metres all the way up to  100m + in complete darkness. The IR light that is omitted cannot be detected by the human eye, the only clue you will get is that is looking directly at the camera you will be able to see a very faint red glow but nothing more. When looking at the footage though a monitor you will get quite a different picture, a well illuminated black & white image showing up surprisingly good detail. If you're trying to be covert then maybe you will feel the infra red gives away the position of a camera, arguably though this kind of camera will be more of a deterrent which surely is the whole point of having a Camera system. The downsides to this tech are only a few, obviously you will struggle to capture number plates due to the chance of IR bounce back, and an image can be over exposed if the camera you are using has a much greater IR range than the distance of the object you are monitoring.

Conclusion
To be honest no one tech is really better than the other, both are very good in their own right and one will not dominate the other in the future. Both technologies will continue to be developed to improve upon the generation before.  The camera choice will almost always be determined by the environment in which it is to be situated.

About the Author

Technical CCTV Engineer for past 15 years

http://www.digitaldirectsecurity.co.uk/cctv-cameras/night-vision-domes.html

http://www.digitaldirectsecurity.co.uk/cctv-cameras/night-vision-cctv-cameras.html

Will a standard PIR work in an area lit by IR lighting?

I have an area that is lit using IR lighting for a CCTV camera. If I install a PIR in this section will it still be able to pickup an IR trigger from a human walking past ?

It will probably work...

The PIR ( passive infrared sensor) usually senses radiation in the range of 8-14 microns - your body heat. The IR illumination used for CCTV is usually limited to silicon sensitivity which cuts off at 1.1 micron on the long wavelength end.

They don't overlap

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