# How many lumens do I need to...



## RWBlue (Aug 16, 2009)

I know most people here are looking for more light, just because and I know it is a dumb question, but since I can not find it with google, I am hoping someone here knows the answer..

Is there a chart which states how many lumens are needed to:
Read in a perfectly dark room, for long periods vs. just enough light to make out a message

Enough light to see to do work.

Enough light to be seen over X amount of distance

Enough light for seeing a person at 20 yards, vs. 100 vs. 1000

Enough light to…and 100 more examples.


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## flatline (Aug 16, 2009)

Hmm...something similar, perhaps, to the decibel charts? (X decibels = whisper, Y decibels = jet engine)

Lux would be a better way of doing it than lumens. For instance, my Quark's moon mode (0.2 lumens) still has a hot spot too bright to read by in a dark room because too much light is at the focal point. The low setting on a Zebralight (3 lumens?) is reportedly just perfect for reading since it's pure flood.

I'll let you know about the zebralight once my wife buys some new shoes (thus, letting me justify a new flashlight).

--flatline


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## Lighthouse one (Aug 16, 2009)

Too many answers for different folks. That's why a variable level light is popular!

I would recommend the Zebralight 3 level for reading and close work jobs (like painting)

My nitecore handles most other wants- except outdoor long range- and there are a ton of lights for that!


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## gem (Aug 16, 2009)

RWBlue said:


> I know most people here are looking for more light, just because and I know it is a dumb question, but since I can not find it with google, I am hoping someone here knows the answer..
> Is there a chart which states how many lumens are needed to:
> Read in a perfectly dark room, for long periods vs. just enough light to make out a message
> Enough light to see to do work.
> ...


 
As far as I've seen, there are no charts to show all the different scales, ratings, effective light distances etc. Even effective illumination of an object vertical is different than say a seeing the ground clearly at the same distance. 
While there are many many flashlights for relatively close distances, fewer flashlights will give you enought light at say 100m and only a few high output flashlights like the Xtar howitzer with 1700 lumens will reach out to 500m. If you want 1000m, get a Xenon with some 50 digit candelpower number on it as they don't use the more accurate measurment of lumens.


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## hyperloop (Aug 16, 2009)

Different levels for different uses, that much is apparent. Also depends on the individual and how well he (or she, but use the he to indicate both sexes) has adapted to the darkness.

But to try to answer your question,

For reading, my room isnt pitch dark but dark enough that you would need some light to navigate and look for stuff, i use my Zebralight H501 on low, which is perfect for reading IMHO, bright enough to read without eye strain but yet not bright enough to wake up my sleeping wife next to me, that light is about 3 lumens if i'm not wrong

to do work? what sort of work? i use the H501W on medium with the fluoroscent lights are on to see the back of my pc when i need to plug stuff in or open it up and mess around with the interiors, in these situations a headlamp is ideal as you need both hands usually

to be seen, that again depends on conditions, ambient lighting etc, a tiny blinking light set against a dark backdrop is very visible but generally, the more ambient lighting you have, the brighter your light must be to be noticed (or strobed)

i like lights as a hobby, dont really need them for work, but they ARE useful and right now, my Nitecore EX10 is doing EDC duty with some other lights in my bag and a Fenix LD01 on the keychain. My friends think i am nuts but who cares 

Different lights for different purposes, if i had one that i could put in my pocket comfortably and have it do everything, man, i think it would have to nuclear powered by some science fiction portable nuclear battery the size of an AA cell and able to put out 0.5 lumens to 10,000 lumens, reflector size and depth wouldnt matter with 10,000 lumens (i think)


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## gem (Aug 16, 2009)

hyperloop said:


> . . . . . if i had one that i could put in my pocket comfortably and have it do everything, man, i think it would have to nuclear powered by some science fiction portable nuclear battery the size of an AA cell and able to put out 0.5 lumens to 10,000 lumens, reflector size and depth wouldnt matter with 10,000 lumens (i think)


LOL. . . . there ya go. Might be a lil heavy with all the lead wrapped around it?


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## Dude Dudeson (Aug 16, 2009)

RWBlue said:


> I know most people here are looking for more light, just because and I know it is a dumb question, but since I can not find it with google, I am hoping someone here knows the answer..
> 
> Is there a chart which states how many lumens are needed to:
> Read in a perfectly dark room, for long periods vs. just enough light to make out a message
> ...


 
Such a chart would be impossible because each example here has so many "it depends" factors involved.


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## PhantomPhoton (Aug 16, 2009)

Let's take a look at some of the variables involved...
First there's differing eyes from person to person. Some people just simply need more light than others to read.
Another factor is the beam profile. Is it a narrow spot throw-y beam or a completely diffused flood? Or some mix of both? It'll take a lot more lumens for a flood light to reach out 100m as opposed to s pure spot light.
Then of course there's color rendition and tint. A light putting out a lot more blue light isn't going to render certain colors as well as a light which is more balanced in tint. 
For further distances there's factors such as atmospheric conditions. When it's moist or raining out in late fall for example, the lumens just seem to get sucked up in comparison to using the same light on a warm summer night.


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## Tomcat! (Aug 17, 2009)

PhantomPhoton said:


> Let's take a look at some of the variables involved...
> First there's differing eyes from person to person.




Worse than that, the eyes in your own head do not perfectly match each other, and for some that mismatch can be quite pronounced. Even if you spend out on corrective lenses and get your eyes as close to 20/20 vision as possible and match them to each other, all that goes out of the window in time because your eyes will deteriorate with age.

The only sensible solution is to join CPF, read the reviews, ask questions, then buy lots of lights to see what matches each of your needs. Research is good but there's no substitute for actually having the light in your hand.


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## Egsise (Aug 17, 2009)

RWBlue said:


> I know most people here are looking for more light, just because and I know it is a dumb question, but since I can not find it with google, I am hoping someone here knows the answer..
> 
> Is there a chart which states how many lumens are needed to:
> Read in a perfectly dark room, for long periods vs. just enough light to make out a message
> ...





> Read in a perfectly dark room, for long periods vs. just enough light to make out a message


ZebraLight H50 3 lumens is perfect for reading imho.

All the other things are bit tricky cause there are so many variables.



> Enough light to be seen over X amount of distance


Stars are actually alien flashaholics playing with hydrogen fusion powered kaziljon lumen pocket rockets, this is a well known fact among human flashaholics.:tinfoil:


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## Outdoors Fanatic (Aug 17, 2009)

My IMR-M3T on 2x18500 is great for reading in a perfectly dark room (with an welding mask on).


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## KD7EIR (Aug 17, 2009)

Egsise said:


> Stars are actually alien flashaholics playing with hydrogen fusion powered kaziljon lumen pocket rockets, this is a well known fact among human flashaholics.:tinfoil:




Now that made me laugh!


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## sygyzy (Aug 17, 2009)

This is a great question and one I thought of last night as well. There should be _some_ chart created. Let's say, amount of light needed to read size x font at y feet by someone with 20/20 vision. I am sure that we have a large enough population here that we could contribute numbers. 

I know the problem is such a chart can't be 100% accurate but who cares. Most charts are just guidelines or suggestions, not the "final word".


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## Tomcat! (Aug 17, 2009)

Egsise said:


> Stars are actually alien flashaholics playing with hydrogen fusion powered kaziljon lumen pocket rockets, this is a well known fact among human flashaholics.:tinfoil:



And they'd still send them to Intergalactic Milky for modding!


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## flatline (Aug 17, 2009)

sygyzy said:


> This is a great question and one I thought of last night as well. There should be _some_ chart created. Let's say, amount of light needed to read size x font at y feet by someone with 20/20 vision. I am sure that we have a large enough population here that we could contribute numbers.
> 
> I know the problem is such a chart can't be 100% accurate but who cares. Most charts are just guidelines or suggestions, not the "final word".



Someone should talk to their optometrist. Surely eye professionals have guidelines about this sort of thing.


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## saabluster (Aug 17, 2009)

Tomcat! said:


> And they'd still send them to Intergalactic Milky for modding!


Thats true. Nothing like getting it done the Milky way.


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## 325addict (Aug 17, 2009)

You know, 20 years ago I read books under the blanket with my old Daimon incan, powered by 2 C-cells. The bulb was 2.2V / 0.3A and I thought, at that moment, it was BRIGHT 
Indeed, for about 15 minutes, acceptable amounts of light came from it. After that time, either the zinc-carbon batteries gave up, or the lamp got black inside :sigh: :sigh: or both, of course :mecry: :mecry:


Nowadays, I would take a mini-mag AA incan to read books in the dark. That one will provide the same light for longer than that bulky Daimon did
:naughty: Luckily, we have 2700mAh AA NiMHs today :thumbsup:

Everything else becomes too bright quickly. And LED-light isn't pleasing to the eyes to read a book, so a LED light is not considered here.

Sometimes, the good old incan Mag AA isn't that bad :green: :green: :green:


On the other hand, in the woods you just cannot have too much light in my opinion, the more you see, the better.
For this purpose, my 300+ Lumen M90 Rattlesnake 13V setup is my favorite. 


Timmo.


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## Tomcat! (Aug 17, 2009)

saabluster said:


> Thats true. Nothing like getting it done the Milky way.





Arrggh! Why didn't I think of that?


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## Dude Dudeson (Aug 17, 2009)

flatline said:


> Someone should talk to their optometrist. Surely eye professionals have guidelines about this sort of thing.


 
They also have rigidly controlled conditions.

I guess a completely darkened indoor environment of specific dimensions, paint color, and color/size of objects within could serve as some kind of testbed, but good luck with getting many people to perfectly replicate it for a point of reference...


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## lctorana (Aug 17, 2009)

sygyzy said:


> There should be _some_ chart created. Let's say, amount of light needed to read size x font at y feet by someone with 20/20 vision.


Here's one.


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## Justin Case (Aug 17, 2009)

The US Army has done a lot of research on target detection, recognition, and identification in low light at the Army Night Vision Lab at Ft. Belvoir. Try Googling various combinations of the terms above. To get you started, try Googling "Johnson's criteria".


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