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Lumens illumination 3366

Admin Team Absolute Zombie Club Posts: 23,216
Lumens illumination
« on: December 31, 2006, 06:19:02 AM »
Other than cheap plastic giveaways, the only flashlights in my home are AA Mini-Maglites. I've got several, and until recently was blissfully unaware that there was anything better. So help me put things into perspective here. I'm seeing all these fancy flashlights posted with a rating in lumens; I thought flashlights were rated in candlepower?

So what are lumens, and how many lumens do my Mini-Mags put out?
 ???

In order to be certain of having the right tool for every job.........one must first acquire a lot of tools
Formerly known as 665ae No Life Club Posts: 3,380 blah blah blah
Re: Lumens illumination
« Reply #1 on: December 31, 2006, 09:39:12 AM »
All I know is that Lumens are a measure of total light output.  If I remember right, it differs from candlepower in that candlepower is measured at a specific spot within the light, so the candlepower rating can differ depending on where the measuring equiptment is placed in the light the lamp produces.

Here's a short explanation I found online:

A LUMEN is a unit of measurement of light. It measures light much the same way. Remember, a foot-candle is how bright the light is one foot away from the source. A lumen is a way of measuring how much light gets to what you want to light! A LUMEN is equal to one foot-candle falling on one square foot of area.

I think a normal 2AA Maglite only puts out 5-6 lumens, but I could definately be wrong.

If you took all the intestines out of your body and stretched them end to end... you would die.
Absolutely No Life Club Posts: 7,777
Re: Lumens illumination
« Reply #2 on: December 31, 2006, 04:57:33 PM »
That is a good explanation.  The lumens measurement attempts to measure the entire amount of light emitting from the device, including the hot spot in the center and all of the spill.  Unfortunately, to get an accurate lumen reading, one must use an integrating sphere to capture all of the light emitted.  A simple light meter cannot be used without the sphere, or some of the light waves will escape the sensor and give an inaccurate reading.

One problem is that many integrating spheres are not properly calibrated to the same standards.  So, if one light is measured in one sphere, it cannot necessarily be compared to another light in another sphere, because those two pieces of equipment may not agree with each other.  This is why you should not directly compare the lumens claims from one manufacturer to another.  Due to the fact that one manufacturer is probably using equipment that is calibrated differently than another, the measurements will most likely not be on the same scale, and in some cases, will wildly disagree. 

With this in mind, you can reliably compare lights from one manufacturer, but compared lumen ratings from one manufacturer to another should only be used as a rough guideline.

One very helpful tool for output comparisons between flashlight models is the output chart on FlashlightReviews.com, here: http://www.flashlightreviews.com/features/output_vs_throw.htm

Please read the intro page before you start comparing.  The lumen and throw numbers that are published here are not in actual lumens, but they are all taken with the same piece of equipment in the same conditions, so these numbers can be compared with some reliability.  The "overall" numbers here, like lumens, attempt to show the total light output.  The throw numbers will give a good comparison of the "reach" of the beam, or how far it will project.
« Last Edit: December 31, 2006, 05:06:45 PM by NutSAK »

- Terry
Admin Team Absolute Zombie Club Posts: 23,216
Re: Lumens illumination
« Reply #3 on: December 31, 2006, 05:04:25 PM »
Hmmm, sounds like another one of those "complex" issues. Thanks though, that helps. Although I'm still trying to understand just how much brighter these new lights are compared to my old Mag Lites?

In order to be certain of having the right tool for every job.........one must first acquire a lot of tools
Absolutely No Life Club Posts: 7,777
Re: Lumens illumination
« Reply #4 on: December 31, 2006, 05:22:31 PM »
It is a complex issue, and it becomes a bit more complex when comparing an LED light to an incandescent light like your Mags.  Due to the physical differences between the parts (bulb, reflector) and the spectrum of light emanating from the device, your eyes will not necessarily detect the same amount of light from both sources even though the lumen measurements are the same. 

The lumen measurement also will not give you any information about the throw or "reach" of the light, as it does not describe the beam characteristics of the light.  The throw is, in part, dependant upon whether the beam is more of a "spot" beam, with good throw, or a "flood", with poor throw.  This is why I like the FlashlightReviews comparison chart, as the throw of different lights can be compared to some degree of reliability.  The throw of a light will also have an effect on how your eyes an brain will perceive the output of the light.

You will find that the incandescents will comparatively throw better than an LED with the same output, due in part to the much wider spectrum of light produced by an incandescent source.  The wider the spectrum, the smaller chance of the light being absorbed by a particular object.  Likewise, your eyes and brain will interpret the brightness of LED lights if the tint is shifted away from "white" and toward a "warmer" or "cooler" tint, because your eye's receptors are more sensitive to some wavelengths of light than they are to others. 
« Last Edit: December 31, 2006, 07:19:13 PM by NutSAK »

- Terry
Admin Team Absolute Zombie Club Posts: 23,216
Re: Lumens illumination
« Reply #5 on: December 31, 2006, 08:59:20 PM »
You will find that the incandescents will comparatively throw better than an LED with the same output..............Likewise, your eyes and brain will interpret the brightness of LED lights if the tint is shifted away from "white" and toward a "warmer" or "cooler" tint, because your eye's receptors are more sensitive to some wavelengths of light than they are to others. 

Okay, this is starting to make a little sense now. I've read in the forums here somewhere about the "Luxeon lottery" and how it is extremely difficult to consistantly produce LED's that put out the same amount of light, in the same proper color.

In order to be certain of having the right tool for every job.........one must first acquire a lot of tools
Absolutely No Life Club Posts: 7,777
Re: Lumens illumination
« Reply #6 on: December 31, 2006, 11:53:26 PM »
Exactly.  This is where "binning" comes into play.  As the LED comes off the assembly line, it is measured for output, color and forward voltage (related to efficiency of the LED) and coded to reflect those values.  You will find that the more reputable flashlight manufacturers will set a tighter binning standard for their lights than those that sell the less-expensive lights.  As the binning standard loosens, the performance and tint characteristics will fluctuate more drastically.

Expect an in-depth article about this from me in the near future.
« Last Edit: January 01, 2007, 12:02:29 AM by NutSAK »

- Terry
Head Turd Polisher Administrator Just Bananas Posts: 63,193 Optimum instrumentum est inter aures
Re: Lumens illumination
« Reply #7 on: January 01, 2007, 12:01:14 AM »
I would appreciate that as I am a little lost already!

Def

Leave the dents as they are- let your belongings show their scars as proudly as you do yours.
Formerly known as 665ae No Life Club Posts: 3,380 blah blah blah
Re: Lumens illumination
« Reply #8 on: January 01, 2007, 12:13:20 AM »
Bin Coding is a method of describing the specs of a LED.  I think the ratings tell you the flux rating, tint, Vf (forward voltage), and color.

If you look at some of the different LED lights out there.  You'll see some of the LED's described as U bin, or R bin, etc. 


If you took all the intestines out of your body and stretched them end to end... you would die.
Absolutely No Life Club Posts: 7,777
Re: Lumens illumination
« Reply #9 on: January 01, 2007, 12:24:30 AM »
Yes, the more reputable companies will spec their lights at a certain flux (or output), as R-bin, T-bin, U-bin, etc., as Mike has mentioned.  However, the LEDs may still very greatly in tint and efficiency due to forward voltage.  The only way to be sure of exactly what bin code you are buying is to buy a light from a custom flashlight manufacturer who will build a flashlight with a requested bin code, or to buy a specific bin-coded LED and modify a light yourself.  I've modified a few of mine and will be able to show you how various codes can change the characteristics of a flashlight.

We are straying a bit from the original topic of this thread...  Bin codes and "luxeon lottery" is only one of many factors that will affect the lumens provided by an LED flashlight.

EDIT:  I guess we're not really straying, just "narrowing focus".   ;)
« Last Edit: January 01, 2007, 12:43:30 AM by NutSAK »

- Terry

 

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