Illuminance is a measure of how much luminous flux is spread over a given area. One can think of luminous flux (measured in lumens) as a measure of the total “amount” of visible light present, and the illuminance as a measure of the intensity of illumination on a surface.
A given amount of light will illuminate a surface more dimly if it is spread over a larger area, so illuminance is inversely proportional to area.
When a Camera Specification refers to Lux level, it is an indication of the lowest light level at which the camera will produce adequate image capture.
It is best to exercise caution when viewing specifications that quote operational Lux levels as low as 0.0001, as (unless the camera incorporates integrated Infrared LEDs or an external light source is available) the quality of an image captured at such a low lux levels is unlikely to be of any use.
|Illuminance||Surfaces Illuminated By:|
|0.0001 lux||Moonless, overcast night sky (starlight)|
|0.002 lux||Moonless clear night sky with nightglow|
|0.27–1.0 lux||Full moon on a clear night|
|3.4 lux||Dark limit of civil twilight under a clear sky|
|10−40 lux||Total starlight|
|50 lux||Family living room lights|
|80 lux||Office building hallway/toilet lighting|
|100 lux||Very dark overcast day|
|320–500 lux||Office lighting|
|400 lux||Sunrise or sunset on a clear day.|
|1000 lux||Overcast day; typical TV studio lighting|
|10,000 — 25,000 lux||Full daylight (not direct sun)|
|32,000 — 130,000 lux||Direct sunlight|