# Inverse Square Law ...or Why a 800 lumen light is only twice as bright as a 200 lumen light

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Boaz
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Inverse Square Law ...or Why a 800 lumen light is only twice as bright as a 200 lumen light

I love the example here because of the flashlight

If we start at 3 lumens and multiply times 4 ..to get a percieved doubling of light.

We start at ..3 ...12...48...200...800.../  next doubling doesn't happen until 3200 lumens ..after 1000 lumens we have real heat and battery issues .

So when someone says either 800 or 1000 lumens  I just shrug because it's almost impossible to see the difference between the two  ..If output gains aren't relating to runtime it's pretty meaningless ...One reason I assume high end manufacturers don't normally overdrive their lights .Although I think even they realize that people love to be lied to  and that Big numbers sell .

καὶ τὸ φῶς ἐν τῇ σκοτίᾳ φαίνει καὶ ἡ σκοτία αὐτὸ οὐ κατέλαβεν

Dc-fix diffuser film  >…  http://budgetlightforum.com/node/42208

Edited by: Boaz on 03/25/2013 - 05:37
scaru
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Unless I'm missing something the inverse square law does not apply here. It applies to calculating the "throw" of a flashlight, which is related to the light measured at different distances; but I don't think it can be used in regards to how the eye perceives light.

Chicago X
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The perception of luminance is logarithmic

http://en.wikipedia.org/wiki/Weber%E2%80%93Fechner_law

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Boaz
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Chicago X wrote:

The perception of luminance is logarithmic

http://en.wikipedia.org/wiki/Weber%E2%80%93Fechner_law

But it doesn't contain a flashlight for illustrative purposes ..

Where as this video does ....it proves that overdriving your lights may have disastrous results .

...and how I learned to love the light

καὶ τὸ φῶς ἐν τῇ σκοτίᾳ φαίνει καὶ ἡ σκοτία αὐτὸ οὐ κατέλαβεν

Dc-fix diffuser film  >…  http://budgetlightforum.com/node/42208

dthrckt
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love the light lol

i love that movie!

anyway – what i’m wondering is

is the perception of throw also logarithmic?

i assume the perception of brightness AT the target follows the same rule/logic

but in a more general sense – some spot in the distance – enough light reaches it for us to see it or it doesn’t…

is this were the difference in bins, or xml vs xml2 will be more evident?

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CarpentryHero
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A 40% increase in brightness is visible to the eye

I’m glad I’m not the only flashlight collector out there, I was beginning to think I was strange.
My name is Kendall and I’m a Flashaholic from western Canada

Tecmo
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I think I figured out why throw is more linear…

The cd is for .25 lumens shining on an object at a distance. Just a little more throw and you might put. .5 lumens on the object, so it looks like it throws twice as well. I’m not explaining it well but maybe you get the idea.