Lumens Lux and lights

P

pmack

Active member
I'd like to thank those guys that helped with this, without their knowledge,help and lights of course I couldn't have put this together.

After reading different performance claims on many of the lights on the market I preached in numerous posts on several forums that those are nothing but personal opinions and not a true comparison or evaluation of a light. How can one guy claim to identify an animal at 250 yards and another guy struggle with the same light to identify an animal at 150 yards. Many factors play into these discrepancies. Weather conditions, moon light, optics, ones own vision and estimation of what is 150 or 250 yards. The only way to evaluate a lights performance is side by side comparison.

There seems to be lots of confusion around lumens. Lumens is a measure of total light. If you remove the reflector from any of these lights it renders it useless as a hunting light yet the lumen measurement with or without the reflector is the same. To get an accurate reading of the lumens produced by a light an integrating sphere is required. It is my belief that none of these lights has ever been measured. The lumen claims are calculations based on the LED manufacturers specs. These are readily available from Cree and I assume others. More lumens is better but you have to focus those lumens to make it perform as a hunting light.

Lux is the most accurate metric of a hunting light. That value is lumens per square meter. It's easily measure with a hand held lux meter. Those that have a focusable light can easily see how lux values change. A broad flood will have a lower lux value than the tight beam from the same focusable light.

The throw of the light depends on the size of the emitter (smaller is better), the surface brightness of the emitter, and the size/design of the reflector (large and smooth is better). Flashlights are usually measured for throw, by measuring the LUX falling on the center of an object placed 1 meter away [note that it may be a pencil beam or a large beam; for lux measurement, that doesn't matter].

100_0059.jpg


LEDs and lux values measured at 1 meter. These meters are calculated for white light. The white and red lux readings may not correlate but the readings for each individual colors do.

SkyRay...........................28000

HS802............................25000

G4.................................23000

Predator Lite..............4300

Ebay Headlamp...............10000

Ebay Headlamp wratten 24.....1600

Ebay Headlamp Rosco Fire.....1500

Night Eyes Headlamp..........2000

Night Eyes Gun light.........10000

XLR250 Green.................13000

XLR250 Red...................9000

Light Malls HS802 red........4700

501B red/aspheric lens......6000

Cabelas with red filter......2500

A lux number of 3 is about the same illumination you see on an object at civil twilight. Full moonlight has a lux value of about 0.3.
For throw comparison purposes you can to calculate the throw distances for an illumination of 1 lux (something I can see clearly in a good scope). It also makes the calculations easier.

Lux varies as the square root of the distance. Therefore, the SkyRay puts 1 lux of illumination on an object at 167 meters (182 yards) [square root of 28000].

 
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Interesting so far, but I think you left out the part about how these numbers were derived/tested. Are these calculated, claimed by the manufacturer, a compilation of tests or maybe you did some testing yourself.

You state that lux is lumens per square meter. Visualizing this, it seems that a flashlight with a wide (flood) beam and a flashligh with a narrow (spot) beam should both have most of their lumens fall within that square meter at a distance of 1 meter. I can understand how that measurement taken at the center instead of an average would sway the numbers in favor of spot beams. (which for most of us is what we're looking for anyways).

Thanks -
 
Good post pmack. You are one of the few people on this forum that truly cares about real research and real numbers when it comes to these lights....it's refreshing. I think the only thing left is to show us some beam shots, even though some of the lights are white, I think showing the beam profile would be a nice update to this.
 
Originally Posted By: erictInteresting so far, but I think you left out the part about how these numbers were derived/tested. Are these calculated, claimed by the manufacturer, a compilation of tests or maybe you did some testing yourself.

You state that lux is lumens per square meter. Visualizing this, it seems that a flashlight with a wide (flood) beam and a flashligh with a narrow (spot) beam should both have most of their lumens fall within that square meter at a distance of 1 meter. I can understand how that measurement taken at the center instead of an average would sway the numbers in favor of spot beams. (which for most of us is what we're looking for anyways).

Thanks -



The luxmeter is in the picture. I set up a jig to hold the light one 39 inches above the the luxmeter. Verified the battery was fully charged and read each light. The lights I owned were read 3 times over several days and an average was derived. When new lights are measured I only measure once but verify the battery is fully charged and also put that battery into a check light with a know lux measurement as a verification.

This wasn't meant as a measurement of each individual light. I'm not claiming that's what each light is or should be. This cheap ebay luxmeter is not a finely calibrated optical instrument, but photogrophers use them all the time and they get the job done. I'm trying to put these lights on an even playing field to show how they really compare to each other. It could be skewed high or low, but they are all skewed the same.

A deep smooth reflector produces the long narrow beam and hot spot hunters desire. An orange peel or textured reflector produce an even distribution of light. I'll post some pics later but this link might explain it. This link actually says lux is not the way to buy a flashlight, their intent was a good overall light. We on the other hand want the tight narrow spot.
http://www.flashlightreviews.com/features/lux.htm

 
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Originally Posted By: iLOVEthehuntGood post pmack. You are one of the few people on this forum that truly cares about real research and real numbers when it comes to these lights....it's refreshing. I think the only thing left is to show us some beam shots, even though some of the lights are white, I think showing the beam profile would be a nice update to this.

I'm not going to mess around with beamshots I got enough time wrapped into this already. I'll post one when I get some time to clarify my example of a focusable light.
 
Originally Posted By: pmackI'd like to thank those guys that helped with this, without their knowledge,help and lights of course I couldn't have put this together.

After reading different performance claims on many of the lights on the market I preached in numerous posts on several forums that those are nothing but personal opinions and not a true comparison or evaluation of a light. How can one guy claim to identify an animal at 250 yards and another guy struggle with the same light to identify an animal at 150 yards. Many factors play into these discrepancies. Weather conditions, moon light, optics, ones own vision and estimation of what is 150 or 250 yards. The only way to evaluate a lights performance is side by side comparison.

There seems to be lots of confusion around lumens. Lumens is a measure of total light. If you remove the reflector from any of these lights it renders it useless as a hunting light yet the lumen measurement with or without the reflector is the same. To get an accurate reading of the lumens produced by a light an optical sphere is required. It is my belief that none of these lights has ever been measured. The lumen claims are calculations based on the LED manufacturers specs. These are readily available from Cree and I assume others. More lumens is better but you have to focus those lumens to make it perform as a hunting light.

Lux is the most accurate metric of a hunting light. That value is lumens per square meter. It's easily measure with a hand held lux meter. Those that have a focusable light can easily see how lux values change. A broad flood will have a lower lux value than the tight beam from the same focusable light.

The throw of the light depends on the size of the emitter (smaller is better), the surface brightness of the emitter, and the size/design of the reflector (large and smooth is better). Flashlights are usually measured for throw, by measuring the LUX falling on the center of an object placed 1 meter away [note that it may be a pencil beam or a large beam; for lux measurement, that doesn't matter].

100_0059.jpg


LEDs and lux values measured at 1 meter. These meters are calculated for white light. The white and red lux readings may not correlate but the readings for each individual colors do.

SkyRay...........................28000

HS802............................25000

G4.................................23000

Ebay Headlamp...............10000

Ebay Headlamp wratten 24.....1600

Ebay Headlamp Rosco Fire.....1500

Predator Lite..............4300

Night Eyes Headlamp..........2000

XLR250 Green.................13000

XLR250 Red...................9000

Light Malls HS802 red........4700

501B red/aspheric lens......6000

Cabelas with red filter......2500

A lux number of 3 is about the same illumination you see on an object at civil twilight. Full moonlight has a lux value of about 0.3.
For throw comparison purposes you can to calculate the throw distances for an illumination of 1 lux (something I can see clearly in a good scope). It also makes the calculations easier.

Lux varies as the square root of the distance. Therefore, the SkyRay puts 1 lux of illumination on an object at 167 meters (182 yards) [square root of 28000].



pmack,
Thank you for taking the time to test these lights and publish your results here..

Proves that the XLR250 is not just a HS802 with a different name like alot of people try to claim that it is..

Jeremiah
 
Originally Posted By: Whiteknucklepmack,
Thank you for taking the time to test these lights and publish your results here..

Proves that the XLR250 is not just a HS802 with a different name like alot of people try to claim that it is..

Jeremiah


According to these numbers the HS802 is twice as bright as the green XLR and almost three times brighter than the red.If I'm doing the math correctly,considering the HS802 was white light and that the red and green will reduce light output by a percentage. It doesnt prove anything,but I could be mistaken......
 
Originally Posted By: ultramag
According to these numbers the HS802 is twice as bright as the green XLR and almost three times brighter than the red.If I'm doing the math correctly,considering the HS802 was white light and that the red and green will reduce light output by a percentage. It doesnt prove anything,but I could be mistaken......


Originally Posted By: pmack
LEDs and lux values measured at 1 meter. These meters are calibrated for white light. The white and red lux readings may not correlate but the readings for each individual colors do.

Originally Posted By: pmack
This wasn't meant as a measurement of each individual light. I'm not claiming that's what each light is or should be. This cheap ebay luxmeter is not a finely calibrated optical instrument, but photogrophers use them all the time and they get the job done. I'm trying to put these lights on an even playing field to show how they really compare to each other. It could be skewed high or low, but they are all skewed the same.


The numbers do not correlate between the different color lights. Lux meters (commonly used in photography) are calibrated for white light or all 3 colors in the color spectrum. LEDs of any color only emit that portion of the color spectrum. Red is around 620nm while green is 520nm based on Cree website. When measureing any individual colord LED your missing 2 portions of the color spectrum.

RGB color model....
http://en.wikipedia.org/wiki/RGB_color_model
 
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not sure this is the best place to post this question but the level of knowledge here is promising.

Is there more than one measurement for lumens? I have seen it abbreviated Lm and LM, and some flashlights have lumens measurements in the 100-250 range and some that seem to be the same light measured at 1000 to 5000 lumens.

Any info on this disparity would be helpful
 
Ultramag,

You might want to look again. There is a HS802 red listed and is only 4700 lux where the XLR250 red is 9000.

Take it how you want it, but the way i see it not the same light!!

Jeremiah
 
I was looking at the HS802 that's 25,000.The red one you refer to is from lightmall,which means there's a good possibility it's a fake Ultrafire.

I own four XLR250's which are mounted on my rifles,so no need to convince me brother it was just a observation.
thumbup1.gif
 
Originally Posted By: j.hennesnot sure this is the best place to post this question but the level of knowledge here is promising.

Is there more than one measurement for lumens? I have seen it abbreviated Lm and LM, and some flashlights have lumens measurements in the 100-250 range and some that seem to be the same light measured at 1000 to 5000 lumens.

Any info on this disparity would be helpful

Don't know why the lumen claims are all over the place. That's one of the reasons I don't believe them. You can't accurately measure an actual number of lumens without some calibrated equipment and an integration sphere. http://en.wikipedia.org/wiki/Integrating_sphere I doubt any of these flash light assembly operations have this equipment. Cree does quote lumen specs. A Cree XPE LED driven at 3.5 watts puts out up to 291 lumens, an XRE driven at 4 watts is listed at up to 251 lumens.

http://www.cree.com/led-components-and-modules/products




 
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Added Night Eyes Gun Light.

SkyRay...........................28000

HS802............................25000

G4.................................23000

Ebay Headlamp...............10000

Ebay Headlamp wratten 24.....1600

Ebay Headlamp Rosco Fire.....1500

Predator Lite..............4300

Night Eyes Headlamp..........2000

Night Eyes Gun light.........10000

XLR250 Green.................13000

XLR250 Red...................9000

Light Malls HS802 red........4700

501B red/aspheric lens......6000

Cabelas with red filter......2500
 
I can appreciate all of yall's research and it is very informative, however i would like a more simple answer. I want to know what yardage is the xlr250 in red good for??? 100yrds or 200yrds??? I am night hunting and would like to be able to use is accuratley at at 150 yards. Does the xlr250 have that capability???

thanks in advance!!!!!
 
The answer isn't that simple.
Do you want to know the distance that your naked eye can see the reflective eyes of predators? Or the distance that you can see reflective eyes using binoculars? Or the distance you can see animals in your scope (depends on scope quality) clear enough to identify and shoot the animal? Or the distance you can see animals (dark animals [black pigs] or light-colored animals) with your naked eye? Will you have the XLR250 mounted to your scope, or just use it for scanning?
And to complicate it more, the effective distance depends on the air humidity, moonlight, and the color of the background vegetation (summer vs. winter).
 
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