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can we measure luminance in cd/ m² with a lux meter? I measured illuminance of 35 lux. and since cd = lux*distance² I took some distance of 30 cm and got 3.15 cd. I know that my led-grid surface is 100cm² then I deduce that the luminance is 315cd/m² is my idea correct? if yes which surface should I take into consideration the led-grid surface (as I have done) or the surface of lux meter sensor

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  • Target brightness for a standard monitor is 120cd/m². 315 sounds rather excessive. What's supposed to be the point of this exercise? – Tetsujin Jun 17 '20 at 12:09
  • this is actually a led grid used to stimulate eyes in medical context – yuri Jun 17 '20 at 14:51
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    Then I'm not sure what this could possibly have to do with photography. – Tetsujin Jun 17 '20 at 15:50
  • not in terms of context but it is still a question about light acquisition – yuri Jun 17 '20 at 20:16
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    I’m voting to close this question because it has nothing to do with photography. – Michael C Jun 19 '20 at 3:33
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In the right situation luminance can be converted to illuminance. But I don't think you have the right conditions... the light source has to be diffused/integrated (such as with an integration sphere) and the only source of light.

In that case the formula for cd/m² is Luminance = (illuminance x reflectance)/π

You might be better off using a camera and converting the exposure value to the luminance value. https://www.ee.ryerson.ca/~phiscock/astronomy/light-pollution/luminance-notes-2.pdf

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  • the attached document seems to go through a method for luminance determination – yuri Jun 17 '20 at 20:13

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