Lux to Lumens

Bigwilly · Oct 2, 2015

Is there a way to convert lux into lumens? Using an Android app to measure lux, can you convert it to lumens or is there an app for android to use my Galaxy S4's light sensor to measure lumens?

reppans · Oct 2, 2015

Assuming you have a good way to collect and homogenize the light (ie, integrated sphere, DIY lightbox, etc) then just use a constant/multiplier derived from a known output calibration light. Keep in mind that every manufacturer, and every CPF reviewer, uses different lumen scales... you'll probably develop you own based on the lights you own.

There is only one reviewer here I've seen that claims true ANSI with laboratory tested calibration lights (ti-force), and I think he's right, but you'll need matching lights to calibrate.

Bigwilly · Oct 2, 2015

reppans said:
Assuming you have a good way to collect and homogenize the light (ie, integrated sphere, DIY lightbox, etc) then just use a constant/multiplier derived from a known output calibration light. Keep in mind that every manufacturer, and every CPF reviewer, uses different lumen scales... you'll probably develop you own based on the lights you own.

There is only one reviewer here I've seen that claims true ANSI with laboratory tested calibration lights (ti-force), and I think he's right, but you'll need matching lights to calibrate.

My question is if there is a calculation to derive lumens from lux. I understand using a light sphere or box to measure the lumens.

Lynx_Arc · Oct 2, 2015

Bigwilly said:
My question is if there is a calculation to derive lumens from lux. I understand using a light sphere or box to measure the lumens.

Try googling lux to lumens conversion

Bigwilly · Oct 2, 2015

Lynx_Arc said:
Try googling lux to lumens conversion

I did but all I see is a complicated formula involving area and a convoluted explanation. I try to not ask questions readily answered by googling.

reppans · Oct 2, 2015

Bigwilly said:
My question is if there is a calculation to derive lumens from lux. I understand using a light sphere or box to measure the lumens.

Yes, as above, there are online calculators - I think they might be reasonably useable with uniform beams like from a mule, but I'm curious how lux can be formula-converted to lumens with anything that has focused hotspot?

more_vampires · Oct 2, 2015

Sticky thread on this: http://www.candlepowerforums.com/vb...-Easy-to-Understand-Lumens-Vs-Lux-Explanation

Swedpat · Oct 2, 2015

The difference between lux and lumen is similar to the difference between pressure and force: Pressure=force/area, and in the same way lux=lumen/area. Therefore there is no standard conversion number between them. If you have 1lumen evenly spread across 1m2 you get 1lux over that area. 1lumen across 1dm2 will be 100 lux. To get 100 lux over 1m2 demands 100lm, and so on.

more_vampires · Oct 2, 2015

Lumens is more like "all the photons," while lux is the concentration of them at a single point.

If you shined a light into a lux meter and panned the light side to side, you'd see different lux readings in the hotspot, spill, etc.

To get lumens, you must perform math and have a device called an "integrating sphere." The sphere must be "calibrated," but this doesn't really involve changing the sphere but coming up with the calibration math. It's kind of a bumpy road to get started.

drmaxx · Oct 2, 2015

Bigwilly said:
I did but all I see is a complicated formula involving area and a convoluted explanation. I try to not ask questions readily answered by googling.

Sometimes physics makes life complicated. However, google is really your friend here. It doesn't get simpler - see for explanation why in the threads above.

more_vampires · Oct 2, 2015

If you're solving a circuit involving reactance (inductors, capacitors,) for example, it doesn't get simple. You gotta nerd-man up, get the pocket protector and graphing calculator, put tape on your glasses, cancel your dates, break up with your girlfriend, and face "imaginary numbers" head on.

Sound like I'm talking smack? Nope.
https://en.wikipedia.org/wiki/Imaginary_number

An imaginary number is a complex number that can be written as a real number multiplied by the imaginary unit i,[note 1] which is defined by its property i2 = −1.[1] The square of an imaginary number bi is −b2. For example, 5i is an imaginary number, and its square is −25. Except for 0 (which is both real and imaginary[2]), imaginary numbers produce negative real numbers when squared.

An imaginary number bi can be added to a real number a to form a complex number of the form a + bi, where the real numbers a and b are called, respectively, the real part and the imaginary part of the complex number.[3][note 2] Imaginary numbers can therefore be thought of as complex numbers whose real part is zero. The name "imaginary number" was coined in the 17th century as a derogatory term, as such numbers were regarded by some as fictitious or useless. The term "imaginary number" now means simply a complex number with a real part equal to 0, that is, a number of the form bi.

You cannot solve a circuit involving reactance without this. To become the Flashlight Alpha Geek, you've got to wrap your head around math or else you're flying blind.

http://www.regentsprep.org/regents/math/algtrig/ato6/electricalresouce.htm

In order to analyze AC circuits, it became necessary to represent multi-dimensional quantities. In order to accomplish this task, scalar numbers were abandoned and complex numbers were used to express the two dimensions of frequency and phase shift at one time.

Only then do you get Mountain Dew and pizza at 4 am.

Bigwilly · Oct 2, 2015

Swedpat said:
The difference between lux and lumen is similar to the difference between pressure and force: Pressure=force/area, and in the same way lux=lumen/area. Therefore there is no standard conversion number between them. If you have 1lumen evenly spread across 1m2 you get 1lux over that area. 1lumen across 1dm2 will be 100 lux. To get 100 lux over 1m2 demands 100lm, and so on.

more_vampires said:
Lumens is more like "all the photons," while lux is the concentration of them at a single point.

If you shined a light into a lux meter and panned the light side to side, you'd see different lux readings in the hotspot, spill, etc.

To get lumens, you must perform math and have a device called an "integrating sphere." The sphere must be "calibrated," but this doesn't really involve changing the sphere but coming up with the calibration math. It's kind of a bumpy road to get started.

drmaxx said:
Sometimes physics makes life complicated. However, google is really your friend here. It doesn't get simpler - see for explanation why in the threads above.

more_vampires said:
If you're solving a circuit involving reactance (inductors, capacitors,) for example, it doesn't get simple. You gotta nerd-man up, get the pocket protector and graphing calculator, put tape on your glasses, cancel your dates, break up with your girlfriend, and face "imaginary numbers" head on.

Sound like I'm talking smack? Nope.
https://en.wikipedia.org/wiki/Imaginary_number

You cannot solve a circuit involving reactance without this. To become the Flashlight Alpha Geek, you've got to wrap your head around math or else you're flying blind.

http://www.regentsprep.org/regents/math/algtrig/ato6/electricalresouce.htm

Only then do you get Mountain Dew and pizza at 4 am.

Thanks guys. I think the pain meds is warping my brain. I don't know why I couldn't comprehend that, even though I understood lux and lumens individually but not together in context. I got it now. The explanations connected the missing dots. Thanks again.

more_vampires · Oct 2, 2015

I like how you pieced that together. Smooth flow. Good work.

Bigwilly · Oct 2, 2015

more_vampires said:
I like how you pieced that together. Smooth flow. Good work.

Thanks again for the explanation.

more_vampires · Oct 2, 2015

:thumbsup:

leon2245 · Oct 2, 2015

Lux to Lumens

Sounds like an Atari 2600 game title.

Bigwilly · Oct 2, 2015

leon2245 said:
Sounds like an Atari 2600 game title.

Or a bad 70's porno. Lmao

TeaSipper · Oct 2, 2015

Lumen is the total amount of light while Lux is the intensity of light. For example, a thrower will show more Lux than a flooder but the flooder has more lumen than the thrower.

Bigwilly · Oct 2, 2015

TeaSipper said:
Lumen is the total amount of light while Lux is the intensity of light. For example, a thrower will show more Lux than a flooder but the flooder has more lumen than the thrower.

That's not quit accurate. I have a thrower with more lumens than a flooder. And a flooder with more lux than a thrower. You need to rethink your description

TeaSipper · Oct 2, 2015

Bigwilly said:
That's not quit accurate. I have a thrower with more lumens than a flooder. And a flooder with more lux than a thrower. You need to rethink your description

Seems I got something mixed here. What's CD?

Lux to Lumens

Flashlight Enthusiast

Flashlight Enthusiast

Flashlight Enthusiast

Flashaholic

Flashlight Enthusiast

Flashlight Enthusiast

Flashlight Enthusiast

Flashlight Enthusiast

Flashlight Enthusiast

Enlightened

Flashlight Enthusiast

Flashlight Enthusiast

Flashlight Enthusiast

Flashlight Enthusiast

Flashlight Enthusiast

Flashlight Enthusiast

Flashlight Enthusiast

Newly Enlightened

Flashlight Enthusiast

Newly Enlightened

Similar threads