Orders of magnitude (illuminance)

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As visual perception varies logarithmically, it is helpful to have an appreciation of both illuminance and luminance by orders of magnitude.


To help compare different orders of magnitude, the following list describes various source of lux, which is measured in lumens per square metre.

Multiple Value Item
0 0 lux 0 lux Absolute darkness
10−4 100 microlux 100 microlux Starlight overcast moonless night sky[1]
140 microlux Venus at brightest[1]
200 microlux Starlight clear moonless night sky excluding airglow[1]
10−3 1 millilux 2 millilux Starlight clear moonless night sky including airglow[1]
10−2 1 centilux 1 centilux Quarter Moon
10−1 1 decilux 2.5 decilux Full Moon on a clear night[1][2]
100 1 lux < 1 lux Extreme of darkest storm clouds, sunset or sunrise
< 1 lux Moonlight[3]
101 1 decalux 40 lux Fully overcast, sunset or sunrise
102 1 hectolux < 200 lux Extreme of darkest storm clouds, midday
400 lux Sunrise or sunset on a clear day (ambient illumination)
104 10 kilolux 10–25 kilolux Typical overcast day, midday
20 kilolux Shade illuminated by entire clear blue sky, midday
105 100 kilolux 110 kilolux Bright sunlight
120 kilolux Brightest sunlight


This section lists examples of luminances, measured in candelas per square metre and grouped by order of magnitude.

Multiple Value Item
10−6 µcd/m2 1 µcd/m2 Absolute threshold of vision[4]
10−4 400 µcd/m2 Darkest sky[5]
10−3 mcd/m2 1 mcd/m2 Night sky[6]
1.4 mcd/m2 Typical photographic scene lit by full moon[7]
5 mcd/m2 Approximate scotopic/mesopic threshold[8]
10−2 40 mcd/m2 Phosphorescent markings on a watch dial after 1 h in the dark[9][10]
100 cd/m2 2 cd/m2 Floodlit buildings, monuments, and fountains[11]
5 cd/m2 Approximate mesopic/photopic threshold[8]
101 25 cd/m2 Typical photographic scene at sunrise or sunset[7]
30 cd/m2 Green electroluminescent source[5]
55 cd/m2 Standard SMPTE cinema screen luminance[12]
80 cd/m2 Monitor white in the sRGB reference viewing environment
102 250 cd/m2 Peak luminance of a typical LCD monitor[13][14]
700 cd/m2 Typical photographic scene on overcast day[7][11][14]
103 kcd/m2 2 kcd/m2 Average cloudy sky[5]
2.5 kcd/m2 Moon surface[5][6]
5 kcd/m2 Typical photographic scene in full sunlight[7][11]
7 kcd/m2 Average clear sky[4][5][6][14]
104 10 kcd/m2 White illuminated cloud[6]
12 kcd/m2 Fluorescent lamp[5][6]
75 kcd/m2 Low pressure sodium-vapor lamp[6]
105 130 kcd/m2 Frosted incandescent light bulb[5][6][14]
600 kcd/m2 Solar disk at horizon[5]
106 Mcd/m2 7 Mcd/m2 Filament of a clear incandescent lamp[15]
108 100 Mcd/m2 Possible retinal damage[4]
109 Gcd/m2 1.6 Gcd/m2 Solar disk at noon[5][6]

See also[edit]

Notes and references[edit]

  1. ^ a b c d e Paul Schlyter, Radiometry and photometry in astronomy FAQ (2006)
  2. ^ "Petzl reference system for lighting performance". Archived from the original on 2008-06-20. Retrieved 2007-04-24.
  3. ^ Bunning, Erwin; Moser, Ilse (April 1969). "Interference of moonlight with the photoperiodic measurement of time by plants, and their adaptive reaction". Proceedings of the National Academy of Sciences of the United States of America. 62 (4): 1018–1022. Bibcode:1969PNAS...62.1018B. doi:10.1073/pnas.62.4.1018. PMC 223607. PMID 16591742.[dead link]
  4. ^ a b c Hahn, Lance (1996). "Photometric Units". University of Pennsylvania Medical Center, Department of Neuroscience. Retina Reference. Robert G. Smith. Retrieved 2013-10-10. (see http://retina.anatomy.upenn.edu/~rob/lance/articles.html for the references within)
  5. ^ a b c d e f g h i Mischler, Georg. "Lighting Design Glossary – Luminance". schorsch.com. Retrieved 2013-10-10.
  6. ^ a b c d e f g h "Lighting Application". NVC Lighting Technology Corporation. Archived from the original on 2012-05-19. Retrieved 2013-10-10.
  7. ^ a b c d based on Orders of magnitude (illuminance), assuming a typical photographic scene has the same reflectance as an 18% gray card
  8. ^ a b Halonen, Liisa; Bizjak, Grega. "CIE Mesopic photometry – implementation for outdoor lighting" (PDF). University of Ljubljana, Faculty of Electrical Engineering, laboratory of Lighting and Photometry. Retrieved 2013-10-10.
  9. ^ "Luminosity in Watches". 2011-09-29. first decay graph of section 3.4 – The Afterglow. Retrieved 2013-10-11.
  10. ^ "Characteristic and comparison between LumiNova G Series and conventional pigment" (PDF). Nemoto Lumi-Materials. 2011-11-09. afterglow graph on p. 1. Archived from the original (PDF) on 2013-12-28. Retrieved 2013-10-11.
  11. ^ a b c based on this table of exposure values, assuming a reflected-light meter calibration constant of 12.5 cd·s/m2
  12. ^ "Screen Luminance Data Sheet" (PDF). Harkness Screens International. Archived from the original (PDF) on 2012-02-27. Retrieved 2013-10-10.
  13. ^ "Brightness and Contrast Ratio". Screen Tek. Archived from the original on 2013-08-26. Retrieved 2013-10-10.
  14. ^ a b c d When sources quote wide ranges of possible values, a (rounded) geometric mean of those values is reported here.[why?] The luminance of the sky in particular, varies by location, season, weather, time of day and part of the sky. The sky near the horizon is often about half as bright as at zenith, which in turn is often about half as bright as the sky near the sun. Dr. Andrew J. Marsh has created an interactive web application that can be used to visualise different sky conditions.
  15. ^ "Basics of light and lighting" (PDF). Philips Lighting Academy. 2008. p. 29. Archived from the original (PDF) on 2013-10-19. Retrieved 2013-10-18.