# How "bright" is a lumen?



## aephilli (Jan 22, 2012)

Being a complete newbe, I've no idea how "bright" a given number of lumens translates to be in the real world. Hoping someone can give me some comparison insight to something I have actually seen and used. As a "fer instance" how bright (how many lumens) is the Garrity keychain light ( http://www.garritylites.com/page75.html ) ? Or a standard incandescent (I think they are?) 2AA Mini Maglight? 
Thanks for any help you can give to shed some light (sorry, couldn't help myself :devil on the question.


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## mvyrmnd (Jan 22, 2012)

It's actually more complicated than that...

Brightness is all about perception. A 2000 lumen light can look less bright than a 500 lumen light, if the 500 lumen light is highly focused and the 2000 lumen light is a wide flood. This is assuming you're aiming them both at a wall at the same distance.

You need to consider two values simultaneously when looking at brightness; the lumen output (a measure of the total amount of light being emitted, think of it as the number of liters of water coming from a hose) and candela (often spoken of as lux @ a given distance), which you can think of as the amount of water from your hose hitting a given spot on the wall at a given distance.

Clear as mud?


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## StarHalo (Jan 22, 2012)

It would be difficult to use the MiniMag as a standard because its output dims continuously throughout its runtime; it averages around 12 lumens though, which is roughly the same output as a candle flame. As noted above, the candle distributes light 360 degrees, whereas the Mag puts it all in one direction, so the Mag seems brighter.


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## jh333233 (Jan 22, 2012)

1lm was like, a burning candle at 1 meter away (was it? by definition we have 1lm=cd/sr)


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## Viper715 (Jan 22, 2012)

Edit: nevermind.


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## Kitchen Panda (Jan 22, 2012)

aephilli said:


> Being a complete newbe, I've no idea how "bright" a given number of lumens translates to be in the real world.



I'd like to find a table that shows what lumens you would expect for various tasks. I think it might go a little like this:
*1-2 lumens: Finding a keyhole, close range work (within arm's reach), close reading, maybe a supplement to dark-adapted vision finding your way around a room. Some mini incandescent keychain lights admit to this level.
* 5-10 lumens: Indoor use, close inspecitions, map reading, testing eyes; the 2 AAA penlight with a #222 prefocus bulb is in this range.
* 15-30 lumens: General household indoor use, moderate range outdoor use ( a few yards); this is the light range that the 2 D cell plastic light with a prefocus bulb generates.
* around 50 lumens: Walking a good trail at night, finding your way in unfamiliar surroundings. 
* 60-200: So-called "tactical" lights; identify a man-size target at firearms range. Power LEDs can give 100+lumens from an AA cell. In my experience, 100 lumens can light up a small suburban backyard (say, 60 feet x 30 feet) and verify the yard is free of the neighbor's cat. 
* 200 lumens and up - Outdoor, moderately long range, search and rescue - you can go up to several thousand lumens in a hand-carried light but I think anything much over 500 is a rather special purpose tool. 
* 500+ lumens- - I understand night-time orienteers use high-power lamps in this range for running unfamiliar trails in the dark. 

Don't take these numbers as anything other than the centers of pretty broad ranges. 

Bill


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## jh333233 (Jan 22, 2012)

Something below 10lm is a 5mm nichia white led
Raid of 5mm would give you 50lm something


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## aephilli (Jan 22, 2012)

StarHalo said:


> It would be difficult to use the MiniMag as a standard because its output dims continuously throughout its runtime; it averages around 12 lumens though, which is roughly the same output as a candle flame. As noted above, the candle distributes light 360 degrees, whereas the Mag puts it all in one direction, so the Mag seems brighter.



Thanks, that helps. I've used a Minimag lots, so now I have a (rough idea of a) comparison.


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## aephilli (Jan 22, 2012)

Kitchen Panda said:


> I'd like to find a table that shows what lumens you would expect for various tasks. I think it might go a little like this:
> *1-2 lumens: Finding a keyhole, close range work (within arm's reach), close reading, maybe a supplement to dark-adapted vision finding your way around a room. Some mini incandescent keychain lights admit to this level.
> * 5-10 lumens: Indoor use, close inspecitions, map reading, testing eyes; the 2 AAA penlight with a #222 prefocus bulb is in this range.
> * 15-30 lumens: General household indoor use, moderate range outdoor use ( a few yards); this is the light range that the 2 D cell plastic light with a prefocus bulb generates.
> ...



Just what I was looking for, thanks a heap.:twothumbs


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## aephilli (Jan 22, 2012)

After a little research at the local china-mart, it looks like the Garrity folks rate theirs at 6 lumens and the Mini Maglight people say 14. This will really help me decide what I want.

Thanks a bunch for the help, guys.

Did I just miss the sticky that has the above numerical comparison info in it? (honest, I looked :huh


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## STR (Jan 22, 2012)

While I don't claim to know a lot about lights or about Lumens I know what I do to see the difference between lights is not shine them on a wall to see the pattern although I do that at times but to see Lumen accuracy for what the companies claim or try to see it is I walk into my bathroom which is about 80" x 80" and I close the door. Then I stand the light up on its end or make it stand up using something to support it if it doesn't stand up on its' own and turn it on high to see which flashlight is providing more light in the room. The way I can tell the JetBeam BA20 is actually putting out more light than the Nebo is by how much brighter the room is using the JetBeam over the Nebo 220 S.O.S Both of these come close to lighting up this small room like the light bulbs but the JetBeam is so much closer to this that it stands out in this test yet when shining them on the wall the Nebo appears brighter.


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## AnAppleSnail (Jan 22, 2012)

A lumen is not brightness, a lumen is output. Let's go with output per area (Photons per area, so to speak, accounting for human sensitivity). Given that 1 lux is 1 lumen per square meter, use this table:

Source from Wiki


120,000 luxBrightest sunlight110,000 luxBright sunlight20,000 luxShade illuminated by entire clear blue sky, midday10,000 - 25,000 luxTypical overcast day, midday<200 luxExtreme of darkest storm clouds, midday400 luxSunrise or sunset on a clear day (ambient illumination).40 luxFully overcast, sunset/sunrise<1 luxExtreme of darkest storm clouds, sunset/rise

For comparison, nighttime illuminance levels are:

<1 luxMoonlight[3]​0.25 luxFull Moon on a clear night[4]​[5]​0.01 luxQuarter Moon0.002 luxStarlight clear moonless night sky including airglow[4]​0.0002 luxStarlight clear moonless night sky excluding airglow[4]​0.00014 luxVenus at brightest[4]​0.0001 luxStarlight overcast moonless night sky[4]​



So if you have a 1 lumen light shining evenly on 1 square meter, then it's about like bright full-moon light. That same lumen spread over a 1cm square will look as bright as an overcast day.


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## gcbryan (Jan 22, 2012)

I think (but am not sure) that one lumen is approximately the output of a birthday candle if you place a piece of white cardboard 1 foot 1 away and only consider the light hitting that cardboard. You would size the cardboard so that it covered 15 degrees. I think 1 lumen produces 1 lux under those circumstances.

This is off the top of my head so someone correct me if I'm wrong. It's close anyway.


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## luketheduke8 (Jan 30, 2012)

*How bright are Lumens?!?!?!?*

I would really like to know before I buy I light how bright 0.2, 5, 6, 10, 30, 60 etc. Lumes are, like could you use real life examples like how bright it would be to walk around a house or outside etc. I think you get it, thanks a ton!!

Merged


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## StarHalo (Jan 30, 2012)

*Re: How bright are Lumens?!?!?!?*



luketheduke8 said:


> I would really like to know before I buy I light how bright 0.2, 5, 6, 10, 30, 60 etc. Lumes are, like could you use real life examples like how bright it would be to walk around a house or outside etc



The problem is that your real world perception of how bright something is depends on how much light your eyes are currently acclimated to. You can't see 2 lumens at all outdoors during the day, yet with dark-adjusted eyes, 2 lumens looks as bright as you'd expect a regular, general-purpose flashlight to look.


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## gcbryan (Jan 31, 2012)

*Re: How bright are Lumens?!?!?!?*

To me the spacing is as important and the lumen figures. The modes are unique enough if the spacing isn't at least x3 as in 3-10-30-90 or something like that. Having something like .2 is nice as well.

There is no difference between 5 and 6 and little between those and 10.


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## mbw_151 (Jan 31, 2012)

*Re: How bright are Lumens?!?!?!?*

There are lots of considerations in picking a light. The three major considerations for flashlight performance are: total output, run time and how that output is distributed, the beam pattern. The post #12 by AnAppleSnail gives an example of a fixed output distributed over two different areas. For the same output, a beam focused one square inch will be very bright and spread on one square yard very dim. A laser like beam will be very bright on a small spot at a great distance, great for spotting but useless for reading a map or lighting an area. This is the "flood" versus "throw" discussion. Beam patterns range across the spectrum. Use up close favors flood, use at distance favors throw. Beam pattern can be modified using a diffuser to move from throw towards flood.

For a given emitter, batteries and circuit, more lumens means less runtime. Two hunderd lumens with throw is great for searching at a distance, 10 lumens of flood is good for reading or looking for your shoes in a tent at night. A light that puts out two hunderd lumens might run a couple hours. The same light at 10 lumens will run a day and a half. Multiple output levels give you efficiency and usability options.

When you select a light consider how you will use the light and what performance is most important to you. The new ANSI label gives lumens and runtime. Some manufacturers give a "throw" distance, but this doesn't adequately characterize the beam pattern.


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## Phil2015 (Jan 13, 2015)

*Stupid question, but what is a lumen?*

Someone asked me this today and I had no idea, I only know that the more lumens you have, the brighter the light.

So what is a lumen?


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## Hogokansatsukan (Jan 13, 2015)

*Re: Stupid question, but what is a lumen?*

Actually, a lumen is a highly addictive substance that somehow is not regulated by the BATFE.
Many here have a serious addiction to said substance, and while CPF may seem like a support group, it is in fact, not. 
Quite the contrary.


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## dc38 (Jan 13, 2015)

*Re: Stupid question, but what is a lumen?*

A lumen is the measure of a cross sectionional hole of any tubular body. Needles, piping, etc.


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## KDM (Jan 13, 2015)

*Re: Stupid question, but what is a lumen?*

Hogo is right, this place is an enabler for lumen junkies. It's going to be hard for anyone to describe to you what only you can perceive. One beauty of having multiple output levels is that you can turn it up or down for your needs. They are also like Pringles, bet you can't stop at one. Good luck.


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## LedTed (Jan 14, 2015)

Kitchen Panda said:


> I'd like to find a table that shows what lumens you would expect for various tasks.Bill



EXTECH has published the following list ...

*Typical Light Levels*

Type
Lux
Foot Candles

Emergency Stairs
20-75 (Lx)
2-7 (FC)

Egress Passages
75-150 (Lx)
7-15 (FC)

Packing Work
150-300 (Lx)
15-30 (FC)

Production Work
300-750 (Lx)
30-75 (FC)

Inspection Work
750-1,500 (Lx)
75-150 (FC)

Detailed Assembly
1,500-3,000 (Lx)
150-300 (FC)


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## AnAppleSnail (Jan 14, 2015)

Lumens make it easy to sell flashlights. "100! 320! 680!" But they aren't helpful for seeing things. It's a long boring discussion, though:

"We see reflected photons, so we are really interested in the intensity of light on the object in question, compared to the intensity of light in the surrounding area, giving an acceptable contrast and signal to your retina to process an image."

So we sell flashlights by lumens. A lumen is:


Plenty to see in a dark room if you're young.
Enough to read a book in bed.
Not enough to see under your car in a lit parking lot
Enough to find dropped keys in a dark parking lot
Nothing at all compared to a streetlight
Plenty to walk on a very familiar sidewalk in total darkness
Not enough to walk through most forests


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## magicstone12 (Jan 21, 2015)

light one little candle in the dark ,this is one lumen,maybe


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## StarHalo (Jan 21, 2015)

magicstone12 said:


> light one little candle in the dark ,this is one lumen,maybe



A candle flame averages 13 lumens, actually. Focused into a single direction, that's about the output of an incan MiniMag on worn batteries, hence the mirrored/lensed candle holders of old.


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## RemcoM (Jan 22, 2015)

AnAppleSnail said:


> A lumen is not brightness, a lumen is output. Let's go with output per area (Photons per area, so to speak, accounting for human sensitivity). Given that 1 lux is 1 lumen per square meter, use this table:
> 
> Source from Wiki
> 
> ...



Hi Anapplesnail, and others,

Can a flashlight with 350 kcd...klux, be more intence at 1 meter distance, than bright direct sunlight?


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## leon2245 (Jan 22, 2015)

> How "bright" is a lumen?




Exactly 1/100 as bright as a Luman.

100 lumens = 1 Luman.


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## AnAppleSnail (Jan 22, 2015)

RemcoM said:


> Hi Anapplesnail, and others, Can a flashlight with 350 kcd...klux, be more intence at 1 meter distance, than bright direct sunlight?



Not many flashlights will. I've charred cardboard with DIY LED arrays touching that cardboard but it is difficult to do with a flashlight instead of a bare LED. 


To double sunlight's intensity on 0.0001 m^2 (1cmx1cm) would require "only" 24 lumens (120000 lux / (0.01m x 0.01m) of photons. But to do this on a hand-sized thing would take 1200 lumens. The bezel of this 204 kCd light is about 48mm. That means we could expect about (204KCd / (0.024^2*Pi))/120kCd x sunlight, or *0.939x* Sunlight on average.

On the other hand, a Cree XM-L at 10W puts out about 1000 lumen. If its 5mm diameter die is 3mm from cardboard, we have a contact area of roughly 10mm diameter. 1000 lumens / (0.004m^2*pi) = 20 million lux. *That's 100 suns.* 

There are some optical laws of physics that mean the peak intensity of a source is always right at the source - Never further away. We use lenses and reflectors to get high intensity further from the flashlight. 

High-end custom searchlight: 0.94 suns at the bezel, less everywhere further

Bare Cree XM-L: 100 suns at the LED dome.

Edit: line breaks, wording.

This is why bare LEDs can cause fingertip burns.


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