Orders of magnitude (illuminance)

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

## Contents

* 1 Illuminance
* 2 Luminance
* 3 See also
* 4 Notes and references

## Illuminance

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

Factor
(lux)  | 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
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

## Luminance

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

Factor
(cd/m2)  | Multiple  | Value  | Item

|
|
|

10−6 | µcd/m2 | 1 µcd/m2 | Absolute threshold of vision[3]
10−5 |  |  |
10−4 |  | 400 µcd/m2 | Darkest sky[4]
10−3 | mcd/m2 | 1 mcd/m2 | Night sky[5]
1.4 mcd/m2 | Typical photographic scene lit by full moon[6]
5 mcd/m2 | Approximate scotopic/mesopic threshold[7]
10−2 |  | 40 mcd/m2 | Phosphorescent markings on a watch dial after 1 h in the dark[8][9]
10−1 |  |  |
100 | cd/m2 | 2 cd/m2 | Floodlit buildings, monuments, and fountains[10]
5 cd/m2 | Approximate mesopic/photopic threshold[7]
101 |  | 25 cd/m2 | Typical photographic scene at sunrise or sunset[6]
30 cd/m2 | Green electroluminescent source[4]
55 cd/m2 | Standard SMPTE cinema screen luminance[11]
80 cd/m2 | Monitor white in the sRGB reference viewing environment
102 |  | 250 cd/m2 | Peak luminance of a typical LCD monitor[12][13]
700 cd/m2 | Typical photographic scene on overcast day[6][10][13]
103 | kcd/m2 | 2 kcd/m2 | Average cloudy sky[4]
2.5 kcd/m2 | Moon surface[4][5]
5 kcd/m2 | Typical photographic scene in full sunlight[6][10]
7 kcd/m2 | Average clear sky[3][4][5][13]
104 |  | 10 kcd/m2 | White illuminated cloud[5]
12 kcd/m2 | Fluorescent lamp[4][5]
75 kcd/m2 | Low pressure sodium-vapor lamp[5]
105 |  | 130 kcd/m2 | Frosted incandescent light bulb[4][5][13]
600 kcd/m2 | Solar disk at horizon[4]
106 | Mcd/m2 | 7 Mcd/m2 | Filament of a clear incandescent lamp[14]
107 |  |  |
108 |  | 100 Mcd/m2 | Possible retinal damage[3]
109 | Gcd/m2 | 1.6 Gcd/m2 | Solar disk at noon[4][5]

## See also

* Photometry (optics)
* Extraterrestrial sky

## Notes and references

1. ↑ 1.0 1.1 1.2 1.3 1.4 Paul Schlyter, Radiometry and photometry in astronomy FAQ (2006)
2. ↑ "Petzl reference system for lighting performance". Archived from the original on 2008-06-20. https://web.archive.org/web/20080620123040/http://en.petzl.com/petzl/frontoffice/Lampes/static/referentiel/present_referentiel_en.jsp.
3. ↑ 3.0 3.1 3.2 Hahn, Lance (1996). "Photometric Units". Robert G. Smith. http://retina.anatomy.upenn.edu/~rob/lance/units_photometric.html. (see http://retina.anatomy.upenn.edu/~rob/lance/articles.html for the references within)
4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 Mischler, Georg. "Lighting Design Glossary – Luminance". http://www.schorsch.com/en/kbase/glossary/luminance.html.
5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 "Lighting Application". http://www.nvc-lighting.com/showuseInfo.Aspx?typeID=42&ID=94.
6. ↑ 6.0 6.1 6.2 6.3 based on Orders of magnitude (illuminance), assuming a typical photographic scene has the same reflectance as an 18% gray card
7. ↑ 7.0 7.1 Halonen, Liisa; Bizjak, Grega. "CIE Mesopic photometry – implementation for outdoor lighting". University of Ljubljana, Faculty of Electrical Engineering, laboratory of Lighting and Photometry. http://www.sdr.si/dokumenti/p01.pdf.
8. ↑ "Luminosity in Watches". 2011-09-29. first decay graph of section 3.4 – The Afterglow. http://www.kronometric.org/article/lume/.
9. ↑ "Characteristic and comparison between LumiNova G Series and conventional pigment". Nemoto Lumi-Materials. 2011-11-09. afterglow graph on p. 1. http://www.nemoto.co.jp/en/products/luminova/pdf/Luminova-G.pdf.
10. ↑ 10.0 10.1 10.2 based on this table of exposure values, assuming a reflected-light meter calibration constant of 12.5 cd·s/m2
11. ↑ "Screen Luminance Data Sheet". Harkness Screens International. http://www.harkness-screens.com/pdfs/general-info/Screen Luminance.pdf.
12. ↑ "Brightness and Contrast Ratio". Screen Tek. http://www.screentekinc.com/resource-center/brightness-and-contrast-ratio.shtml.
13. ↑ 13.0 13.1 13.2 13.3 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.
14. ↑ "Basics of light and lighting". Philips Lighting Academy. 2008. p. 29. http://www.lighting.philips.com/pwc_li/au_en/connect/Assets/basicsoflight.pdf.

* v
* t
* e

Orders of magnitude

Quantity|

* Acceleration
* Angular momentum
* Angular velocity
* Area
* Bit rate
* Capacitance
* Charge
* Computing
* Currency
* Current
* Data
* Density
* Energy / Energy density / Energy flow density
* Entropy
* Force
* Frequency
* Inductance
* Illuminance
* Length
* Luminance / Luminous flux
* Magnetic field
* Mass
* Molarity
* Momentum
* Numbers
* Power
* Pressure
* Probability
* Radiation
* Resistance
* Sound pressure
* Specific energy
* Specific heat capacity
* Speed
* Temperature
* Time
* Viscosity
* Voltage
* Volume

See also|

* Back-of-the-envelope calculation
* Fermi problem
* Powers of 10 and decades
* 10th
* 100th
* 1000000th
* Billionth
* Trillionth
* Metric (SI) prefix
* Macroscopic scale
* Microscopic scale
* Quantum realm

Related|

* Astronomical system of units
* Earth's location in the Universe
* "Cosmic View" (1957 essay)
* To the Moon and Beyond (1964 film)
* Cosmic Zoom (1968 film)
* Powers of Ten (1968 and 1977 films)
* Cosmic Voyage (1996 documentary)
* Cosmic Eye (2012)

* Book
* Category

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