# How many lumens is enough for a weapon light



## CSSA (Aug 30, 2013)

I have a Foursevens Maelstrom X7 mounted on an AR Carbine and am debating swapping it out for a Maelstrom MM-X with burst mode. I'm wondering at what point more lumens will no longer be beneficial. What are your thoughts?


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## cland72 (Aug 30, 2013)

this is a point of great debate. some people say that, indoors, you don't need more than 100-150 lumens. other say that the surefire fury (500 lumens) is perfect for use indoors.

i would ask, what is your need/want here? is the X7 not illuminating targets adequately at distance, or do you desire more flood? i think you'll get better responses if you help us with what your specific goal is with regards to the weapon mounted light.


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## LightOnAHill (Aug 30, 2013)

I would say indoors 150 with a tight hotspot is fine. For example. I have a quark AA turbo head on a single AA body that I usually run a 14500 in but if I put a single AA in it it gives about 125 lumens and in a dark house that's plenty.

honestly, indoors, a good tactical light for defense should be used in moonlight mode, IMO. I have the quark turbo x with burst mode set to moonlight mode on the nightstand next to my sig 40, and consider it a great setup.


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## m4a1usr (Aug 30, 2013)

CSSA said:


> I have a Foursevens Maelstrom X7 mounted on an AR Carbine and am debating swapping it out for a Maelstrom MM-X with burst mode. I'm wondering at what point more lumens will no longer be beneficial. What are your thoughts?



You have only specified brightness as one form of distinction between lights. There are many, many different usage scenarios not referred to in your post. Some very simple basic questions need to be addressedprior to offering quality advice.
1) Are you a LEO and your weapon used for daily use?
2) Are you LEO and part of a dynamic entry team?
3) Are you a civilian with home protection interest?
4) Are you private security for property, premise’s or personnel?
A weapon mounted light is finely divided upon its primary mission. Ultimate brightness or max lumens downrange is most often desired by home defense users. Blind the source. Disorient them. Brightness can be good in this situation. And high frequency flashing is your friend. Simply shinning huge lumens is not always the best choice
But if foe search or going “Active” is of concern. Than never use brightness or max lumens as your guide. The reason is loss of night vision or situation adaptation. Whether using NOD devices or just plain reaction, brightness is your enemy. 
I did two tours in Iraq and whether using NOD’s or max brightness methods neither was ever a determining factor in success. Diligence.Careful light practice uses did. Most of the time if NOD’s is available than any lumen broadcast was useless. You ended up standing out like a sore thumb to those wanting to find you.
So never go “Active” or broadcast your presence if possible.I don’t care if your using IR or just plain flooding the search area. 3RD​ gen NODs doesn’t need any illumination assistance.


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## m4a1usr (Aug 30, 2013)

And read this. Damn good info! http://www.candlepowerforums.com/vb/showthread.php?369229-Of-Lights-And-Lasers


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## ico (Aug 31, 2013)

I'd say 200 lumens is enough specially for indoors. I'm not saying this is for all situations you guys but the 200 is good enough. The old/semi-old surefires with a max of 200 lumens were already the standard and some would even say that more than 200 is overkill. But that's their opinion. YMMV but for others, 200 is good.


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## SmokeJumperr (Aug 31, 2013)

Something to consider as probably arleady mentioned are your use(s) and frequency of use. 200 lumens is the minimum I would suggest and is kinda of a base standard to go from. My working guns currently utilize a SF Scout 500 lumens and a 500 lumen Fury, for some experimentation. I know some seem to say that over 200 is too much light, but I've not experienced too much light in building searches and open area searching, use of NODS is a bit different and then IR is into play. I don't claim to be an expert, just going off of my uses and experiences. I have no knowledge of your current set up as my only use with WML's are with SF and Streamlight. I have not gone wrong with either of these, other then cost is a factor when it comes to various SF models. Good luck in your choice/purchase.


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## TEEJ (Aug 31, 2013)

Lumens, as mentioned, are part of the specs to consider for out put. Cd is the other light related spec.

Essentially, the overall goal of a weapon light is to do some combination of allowing you enough light to aim the weapon, enough light to identify the target, and enough light to identify the target context.



So, you start typically with a consideration of what the maximum range of the target scenario would be...as you want your light to be able to illuminate it at least at that range.

So, if you want the scene illuminated at 50 meters, or 150 meters, or 500 meters, etc, that is the starting point, as that starts the first step in knowing what cd you want.


The second step to know what cd you want is the use of that illumination. Is it just to aim with, or, will it be held on the scene to allow either aiming, and/or watching the subjects/targets in case one wants to make a break for it/go for a weapon, throw evidence into the bushes, etc.

The further away the subject, the more light, proportionally, is needed to resolve details. the reason has mostly to do with the part of your eye NEEDED to resolve details having the WORST night vision/low light capability. This is also the part of your vision you aim with, the fovea.


MOST people need ~ 1- 5 lux on a target to aim at it at long ranges...depending on the scope, their night vision/adaptation, the target's contrast, etc.

To get 1 lux on target, you need a light with a cd that is the square root of the needed distance, in meters.

So if you need to get one lux on a target 200 meters away, you need a light with a cd of 200 x 200 = 40,000 cd.

To get 5 lux on the same target, you'd need 5X more cd...or 200,000 cd, and so forth.


OK, so lets say you have now decided on the range, and the lux on target AT that range that would make sense...

...You now look at the use in terms of the size of the beam/width on the target at that range.

If you want to only aim, you can have a very tight beam that just puts light at the cross hairs. If you want to be able to see if someone might be moving across the line of fire before they are in the way, etc, and/or want to have a small gang of perps lit up to make sure they are behaving, or not, you might want a beam width that is a lot wider.

This is where the beam ANGLE comes into play...as that dictates the width of the beam at any given distance.

A quick way to estimate the beam width you want is to pick a width at a given range, and then divide it by 0.018 x that range....

IE: You decide you want an at LEAST 10 meter wide beam at a 100 meter range....

..so you take 10 m/(0.018)(100 m) = 5.5º beam angle (Minimum beam angle to GET a 10 m wide beam at 100 m range).



You THEN look at if a WIDER beam would hurt anything...and pick an upper beam angle range if appropriate, and otherwise just be sure the light has at LEAST the minimum beam angle.



OK, NOW you know the beam angle, and the cd needed.


If you want to ALSO specify the LUMENS, think about WHAT you will then use the lumen spec FOR?





Remember that it takes a LOT more lumens to paint a larger surface area (Like a flood light)...and a teeny number of lumens can make a small bright dot of light (Like a laser pointer).


If you think of the lumens as what your light sends OUT, and lux as what bounces back to your eyes...you will get the important part of the relationship. Essentially, you can't SEE lumens, only Lux.


If you imagine that lux is like the DEPTH of water, and the deeper the water, the brighter the target will look to you...and the lumens are the TOTAL water the light can send out...

Imagine that you have a shot glass of water...and its bout an inch deep or so...and you look down into that shot glass, and see that inch of depth as a certain brightness.

Now, pour that shot glass into an empty wading pool, say about 3' wide. How DEEP is that same water, and how bright will that SAME number of lumens look to you?

Its no where near an inch deep anymore, its barely a thin film of a puddle in the pool. The same lumens would essentially go from bright to dim.


So how MANY lumens is "ENOUGH"?




Why even ask?

You only need to use the cd/lux for a weapon light output...as that tells you what you are actually trying to evaluate as far as output, and the beam angle to narrow the selection down to the intended task.


The 500 L Fury for example, as mentioned aways above, is a popular indoor/short range weapon light. It can light up a wide area at once, for situational awareness, yet have enough lux on target to aim with. If it was 1,000 L, it would work even better of course....as we already know the beam angle has proven useful. 

When the Fury would be less useful is where you and your compadres might be in a proximal firing position, and the spill from your light might illuminate THEIR positions. Then, you might want a light with little to no spill, to make YOUR position a simple point of light, but w/o context to those your light is shining AT. That way, if you pop and move, they don't have a picture of to where that might be to, etc. 

And so forth.

So there is no lumen number, in of itself, that's "Enough" or not enough, etc. 

You really need to think about the ranges and uses of the light at those ranges, to start the process....and go from there.


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## the badger (Aug 31, 2013)

My $0.02:

I have an older X300 and a new X300 Ultra. At first I loved how bright the X300U was and couldn't justify keeping my older version. But, as I was testing both of them indoors and out with police friends, we quickly agreed that the X300U 500 lumens was WAY too much for effective indoor use. It was so blinding, especially when shining at a white wall or ceiling, that we felt it was in our disadvantage to adopt it for indoor and/or handgun use (close range). So...
I threw a QD mount on the X300U and now it's used on my Benelli M4 and AR. I kept my older version X300 for use on my G19 and indoors / close range situations.


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## TEEJ (Aug 31, 2013)

the badger said:


> My $0.02:
> 
> I have an older X300 and a new X300 Ultra. At first I loved how bright the X300U was and couldn't justify keeping my older version. But, as I was testing both of them indoors and out with police friends, we quickly agreed that the X300U 500 lumens was WAY too much for effective indoor use. It was so blinding, especially when shining at a white wall or ceiling, that we felt it was in our disadvantage to adopt it for indoor and/or handgun use (close range). So...
> I threw a QD mount on the X300U and now it's used on my Benelli M4 and AR. I kept my older version X300 for use on my G19 and indoors / close range situations.



This is a case of choosing too small a beam angle...and then choosing a dimmer output to compensate, rather than going to a wider beam angle for the same lumens, or, increasing the beam angle and lumens so as to avoid glare, yet illuminate a wider area.


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## CSSA (Aug 31, 2013)

The intended use is for home defense and I doubt if the maximum likely range would be over 30 yds. For outdoors pest removal I use a shotgun or .22 LR. The X7 does an excellent job and provides enough light for target identification and more than enough for aiming, but I've been wondering if the added power of some of the newer lights might be enough to cause an intruder to pause and buy a few more seconds to get a surrender before having to shoot. On the other hand too much light that hits a wall and reflects back isn't altogether pleasant either.


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## TEEJ (Sep 1, 2013)

CSSA said:


> The intended use is for home defense and I doubt if the maximum likely range would be over 30 yds. For outdoors pest removal I use a shotgun or .22 LR. The X7 does an excellent job and provides enough light for target identification and more than enough for aiming, but I've been wondering if the added power of some of the newer lights might be enough to cause an intruder to pause and buy a few more seconds to get a surrender before having to shoot. On the other hand too much light that hits a wall and reflects back isn't altogether pleasant either.



All true.

If you are not night adpated, the glare off a white wall is rarely an issue, but if you are adapted, it takes very little light to see, and glare is a common problem.

The flip side is that the glare off a wall represents a tiny fraction of the glare of the beam itself in the intruder's eyes...IE: If what bounces BACK is hard on YOUR eyes, imagine the way the wall's eyes must feel, etc.


So, for home defense, you need to decide on how you will do the defending. For example, if you paint your walls a flat black, they don't glare, but your wife might glare at you instead. If you hang a tapestry, or use flocked wallpaper, etc, they don't glare, and so forth.

You might want the option of using night vision, so that your light is not an aiming point to an armed assailant....or use an indirect source of light to blind/illuminate the intruder, say with a switch by the bed, that turns on a light that's to the side of the room aimed at the doorway, etc. That way, the intruder is blinded, and, the light is not a dangerous aim point...and you don't have bounced back light.

Of course, if wakened at 3 am, YOU will feel that even a little light is pretty much too bright...and, you might not NEED ANY additional light to see an intruder. A night light by the door might be plenty. It won't blind the intruder either though.


So, back to how to defend...are you looking to aim and fire, or intimidate into submission? Laser sights? Are you planning on your door opening, it waking you, and you firing at whomever's there, and so forth.

Do you have a defensive position, say a night table or other structure able to withstand return fire/act as cover, that you want to be able to have time to get behind/get your sig other behind?

What about kids in other rooms?

Is the bedroom the last line of defense, or is your home set up so you will know when they breach the interior downstairs too, etc, and trigger offensive actions?

Is there a safe room you need to get your family too?

And so forth.

All these types of things dictate what type of lighting solution(s) will work best.

Generally, despite the 3 am night adapted issues, making the OTHER guy see spots generally works better than JUST being able to SEE the other guy...as the other guy has the FULL blast of light, and you only have the reflected light to adjust to.

You DO generally want to know if you are about to blow your daughter's boy friend's head off for trying to hook up on the sly at 3 am, and getting caught, or if its a burglar or rapist, etc. So seeing is a starting point. After that, its all variables.


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## Rich2250 (Sep 1, 2013)

It's amazing how much energy is expelled on this subject, but then there are at least two books, that I know of, devoted entirely to the use of the 'comma'. 

So by now your undoubtedly befuddled by yonder volumes of info... so here's your nutshell; "You must be shapeless, formless, like water" -Bruce Lee

There are many applications to be considered. You should always use the minimum amount of light necessary. 100 lumens can blind you by its reflection in a dark room with a white wall. 500 lumens will blind you with its reflection when shone in dark woods. A p60 in the 150-200 lumen range with a red flip up filter is my general rifle light. Some soldiers in the sand were taping photon micro's to their rifles to provide the 8 or 10 lumens necessary to navigate without attracting fire. Use your head and imagine the real life scenarios you may be addressing. If you are in a team, you must never profile a team mate. You may be tempted to "go wild" with lumens in an IR/NV app so that your confederates can concentrate fire on locus. There are probably infinite answers here. 

-Be safe, have fun, my deuce, peace.


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