Luminance L

Unit of measurement: candela per square metre [cd/m2]1 [cd/m2] = 0,0001 cd/cm2 Luminance L is measured brightness of a light source or an illuminated surface. The eye is very good at distinguishing between different luminance values:

Light source
Average luminance [cd/m2]
Light source
Average luminance [cd/m2]
Xenon short-arc lamp
200 000 - 5000 000 000
Candle
7 500
Sun
1 600 000 000
Blue sky
5 000
Metal halide lamp
10 000 000 - 60 000 000
Specular louvred luminaire
100
Incandescent lamp
2 000 000 -26 000 000
Preferred values for indoor lighting
50 - 500
Compact fluorescent lamp
20 000 -70 000
White paper at 500 lx
100
Fluorescent lamp
5 000 - 30 000
White paper at 5 lx
1
Sunlit clouds
10 000