Lighting for CCTV surveillance

When capturing video in CCTV surveillance applications, there are three essential elements involved.

Camera:

Make sure the camera has the correct sensitivity for the application.
Sensitivity measures how the camera will respond to a certain level of light to obtain an acceptable picture. Sensitivity is typically measured in lux (1 lux = 1 lumen per square meter), with all camera manufacturers stating the minimum lux level needed to produce acceptable images. Camera manufacturers rarely explain where the minimum LUX level should be measured. Is it the minimum light on the scene, at the front of the lens, or on the camera image chip?

Lens:

The lens must match the camera for the proper amount of light to pass through it.
The lens aperture, or f-stop, determines how much light passes through it to the camera chip. The lower the f-stop, the more light the lens will pass. Many manufacturers will specify a certain f-stop lens with a specific camera. Using the lens specified will guarantee that the proper amount of light will pass through the lens, providing an adequate picture at a certain light level.

Illumination:

Unless we have light, we will have no video images from the camera. There are many sources of light. Some are good and some are not so good for CCTV surveillance.

1. Incandescent lamps - The bulb life is limited and these lights are very inefficient. The maintenance costs on this source of lighting are very high.

2. Fluorescent lamps - These lamps are more efficient than incandescent but still waste up to 60 % of the input energy to heat. These are commonly used indoors and are not used in outdoor applications.

3. High Intensity Discharge (HID) lamps - These are very good for CCTV applications due to their 60 – 80% efficiency and their ability to provide excellent color rendition. Low-pressure sodium is a form of HID lamp but is unsuitable for CCTV applications due to its yellow tinge. The best HID source in use today is metal halide. Metal halide bulbs provide cool white light and have excellent color rendition.

4. LEDs - LEDs are now considered to be the green solution to outdoor lighting. They are extremely efficient, and their reliability cannot be matched.