Low Light, Day and Night, Infrared and Lux Rating
Introduction
Lux is the international unit for measuring illuminance. It stands for lumens per square foot and measures the amount of light spread over a given area from a light source a meter away. Some common lux ratings are:
| Example | Illuminance |
|---|---|
| Direct sunlight | 32000 - 130000 |
| Daylight | 10000 - 25000 |
| Well lit office | 500 |
| Sunrise or sunset | 400 |
| Minimum light for easy reading | 300 |
| Passage way | 50 |
| Main road lighting | 15 |
| Side road lighting | 5 |
| Full moon overhead | 1 |
| Full moon on a clear night | 0.27 |
| Quarter moon or cloudy night | 0.01 |
| Total starlight | 0.0001 |
Low light, Day and Night, Infrared
In CCTV cameras, lux rating indicates the minimum amount of light needed for good picture quality. The lower the lux rating, the better a camera sees in the dark. Some cameras are designed specifically for low light conditions. In general, color cameras require more light than black and white cameras. Day and night cameras combine the best of both worlds. Even without infrared LEDs, they can see in environments that have a lux rating between 0.05 and 0.5. They deliver color video during day time and black and white video during the night.
Infrared cameras are superior to non-infrared cameras in terms of viewing in the dark. Because they provide a light source of their own in the form of infrared light emitting diodes (LEDs), they can operate at 0 lux and see even in total darkness. An infrared camera with 50 LEDs is capable of projecting light up to 30 meters away while one with 12 LEDs can only project 10 to 15 meters away. There are also infrared cameras with high powered LED lamps. One high powered LED lamp is roughly equivalent to 4 standard LEDs.
What are infrared LEDs?
Infrared LEDs emit light in the infrared spectrum. This light is not visible to the naked eye but is seen by the sensor of the camera. Thus when infrared LEDs are turned on, a camera is able to see details of an area even if the actual environment is dark.
References
- "Lux." Wikipedia The Free Encyclopedia. Wikipedia, 30 Jul 2010. Web. 22 Aug 2010.
- What does LUX rating mean in CCTV?." CCTV Camera Pros. CCTV Camera Pros, 29 May 2010. Web. 22 Aug 2010.
- "Lux Light Level Chart." IP CCTV specialists use-IP Limited. use-IP Limited, n.d. Web. 19 Sep 2010.
