.25 lux reading

hahoo · Feb 11, 2017

is it the same as .25 lumens, say if your flashlight has a .25 lumen mode ?
if your flash light has a .25 lumens low mode, do you check it 1 meter from the light ?

Scourie · Feb 11, 2017

Not as simple as that. Lux is a measure of peak intensity, lumens is a measure of total output. There's no way to relate the two as it all depends on beam profile.

meeshu · Feb 11, 2017

As mentioned above, the relation between Lux and Lumen is not quite straight forward.

But there is an equation that actually relates the two quantities -

Lm = Lx . 2 . π . x2 . (1 - COS(α/2))

Where Lm = Lumens; Lx = Lux; π = Pi (3.141592654 . .); x = object distance from light source; α = light beam angle (in degrees)

Note that the light beam angle has to be known to determine the relation between Lumens and Lux.

Scourie · Feb 11, 2017

In addition to the beam angle being known, the lux across the beam would have to be constant. Not many flashlights achieve that.

.25 lux reading

hahoo

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Scourie

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meeshu

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Scourie

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