Lux

From FIS Freestyle wiki

A lux meter for measuring illuminances in work places. The lux (symbol: lx) is the SI unit of illuminance and luminous emittance. It is used in photometry as a measure of the apparent intensity of light hitting or passing through a surface. It is analogous to the radiometric unit watts per square meter, but with the power at each wavelength weighted according to the luminosity function, a standardized model of human brightness perception.

Illuminance	Example
10^-5 lux	Light from the brightest star Sirius
10^-4 lux	Total starlight, overcast sky
0.002 lux	Moonless clear night sky with airglow
0.01 lux	Quarter moon
0.27 lux	Full moon on a clear night
1 lux	Full moon overhead at tropical latitudes
3.4 lux	Dark limit of civil twilight under a clear sky
50 lux	Family living room
80 lux	Hallway/toilet
100 lux	Very dark overcast day
320 lux	Recommended office lighting
400 lux	Sunrise or sunset on a clear day. Well-lit office area.
500 lux	Lighting level for an office according to the European law UNI EN 12464.
1,000 lux	Overcast day
10,000–25,000 lux	Full daylight (not direct sun)
32,000–130,000 lux	Direct sunlight