Beam angle vs Luxeons?

rickypanecatyl

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Hey y'all! I'm pretty new to this and am having troulbe figuring out the units used to show the difference between a flood light, a distance thrower and something in between.

I used to make homemade lights with cordless drill batteries and MR11/16 bulbs. Some of those bulbs were more vague and were advertised as narrow spot, spot, narrow flood, flood while other brands actually gave you the degree of the angle. I think 4 degrees was the narrowest beam I saw.

I'm getting the feeling reeding this forum that the luxeons (sp?) gives you guys that info, but I haven't figured out how it works. Any chance someone could explain it to me? Thanks!! :)

Also similar question on this line, is there any industry standard for how far a beam reaches. For instance if your looking at Inova flashlights in target they say things like "see for 225'" "be seen for 2 miles". Does that mean it can light up a reflective traffic sign from that distance?

thanks
 

Lighthouse one

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On the first page...right side column. THe Welcome Mat. Start there. THere have been lots of these discussions before. THe info is out there!
 

rickypanecatyl

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Thanks ... I combed all thru the wiki and from the FAQ got that lumens measures overall light output and lux measures intensity - that a laser can have low lumens but extremely high lux.

I couldn't find anywhere where it told HOW to use lux measures. I'm assuming higher lux numbers will throw a beam farther. I'm guessing that if you were really good w/ the numbers and you had both the lumens and lux you could get an idea of the beam angle?

Here's a guess - can someone confirm or correct my "lux test".

True or False
2 lights that both put out 20,000 lux would have a beam that reached the same distance? (T/F)

Multiple choice
If one put out 200 lumens and the other put out 400 lumens they would both reach the same distace but:
a.) the 2nd light would have 2x the spill area
b.) the 2nd light would have the same size spill area, but 2X as bright
c.) both a or b
d.) neither - the original statement is false.

Essay question
What link is there, (if any) between the lux # and the Target store flashlight package info lines "can see x meters and can be seen Y meters" where y is usually about 10X greater than x.

Extra Credit
What light is durable, dependable and can throw as well as a Thrunite Catapult with just as much spill but is only 1/2 the size, can run on both primaries and rechargeables, has a cool selector ring like JetBeams RRT 1 and costs less than $200?
 
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rickypanecatyl

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My test must've been too hard :whistle:

Is it safe to say that all 19,400 lux flashlighs can light something up the same distance away but those with higer lumens are lighting up a bigger spot?
 

HKJ

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True or False
2 lights that both put out 20,000 lux would have a beam that reached the same distance? (T/F)

Mostly true, but lux measurements at 1 meter might not be correct.
There is also a very big difference between beam shapes, a large hot spot will be a lot more useful than a dot from a laser.

Multiple choice
If one put out 200 lumens and the other put out 400 lumens they would both reach the same distace but:
a.) the 2nd light would have 2x the spill area
b.) the 2nd light would have the same size spill area, but 2X as bright
c.) both a or b
d.) neither - the original statement is false.

Neither, throw and lumen are not related. Try looking at a zebralight and a DBS, they can have nearly the same lumen (Old DBS, Zebralight H60), but one can be a floodlight the other a thrower.

Essay question
What link is there, (if any) between the lux # and the Target store flashlight package info lines "can see x meters and can be seen Y meters" where y is usually about 10X greater than x.

What link there is depends on the manufacturer, there is no standard for these types of specifications.
 

rickypanecatyl

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Is lux proportional to distance of beam throw? will a 10,000 lux light throw a beam 2X as far as a 5,000 lux light?
 

Gunner12

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It's not linear. It takes 4x the lux to throw twice as far presuming same beam pattern.

Can see XX meters means you can see that far with your own eyes when pointing the light at something(take the distance with grains of salt)

Can be seen XX meters means someone standing XX meters away can see that the light is shining. Take an airplane light. You can see the light flashing from the ground, but the pilot can't you.

If you knew lumen and lux, you still won't be able to accurate know the beam angle. Imagine a torch with all it's light concentrated at a central point and no side spill, now take a torch with lots of spill and with the same lux and hotspot angle at a set distance as the first torch. The second will have a lot more lumen then the first torch since the second torch also has spill light vs no spill for the first torch.

Luxeon is a LED company.

For your task, I'd suggest looking at optics (the same size optic can have different models with different angles).
 

hoongern

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Assuming you have the lux @ 1m readings, one way to calculate how 'far' it would throw is to define "lighting up something" as illuminating it with 1 lux.

If you use that definition, you can simple square root the 1m/lux readings to get how far it will "throw"

i.e. 5000lux would throw sqrt(5000) = 70.7 meters
20000lux would throw sqrt(20000) = 141 meters
100000lux - 316 meters

etc.

The distance would refer to how far the beam would go before it goes down to 1lux.

Whether you can see the thing you're illuminating at that distance is a different issue, since a sign post, white wall and a tree reflect light differently.
 

rickypanecatyl

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That was really helpful - thanks guys ... I think I'm just starting to get it :)

How bright is 1 lux? Would you be able to see a 20,000 lux beam on a reflective traffic sign on a house 141 meters away? Would the 1 lux it came down to be enough to see on the side of a house in the pitch black 141 meters away?

I noticed Jetbeams RRT-1 claims it can thow a beam 500 meters ... does that mean it has 250,000 lux at 1 meter and 1 lux at 500 meters?
 

Gunner12

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1 lux is 1 lumen over a 1m x 1m surface. Here's a wikipedia article on Lux. A full moon on a clear night could be 0.27 lux - 1 lux depending on where you are.

Depending on how well adapted to the night your eyes are and how well you want to see at distance, 1 lux might not be enough, or more then enough. Ambient light is also important(a flashlight during the day won't be that visible). You need less then 1 lux for a reflective sign to be seen.

What light do you have right now? There might be lux figures for it and you might be able to test things yourself.

Also, the lux figure measured at 1m is not always an accurate representation of throw. Imagine a perfect laser, zero divergence of beam. In that case, it won't matter where you measure the throw, since it will be constant no matter how far away you are(presuming a vacuum). Turn on a light, hold a sheet of paper very close to the light and slowly more the paper away. Notice how the hotspot doesn't start diverging immediately (well, for most lights). For some lights, that effect extends beyond 1m.
 

rickypanecatyl

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Excellent article Gunner! (Though I must confess it did make my brain hurt a bit trying to understand it all!) Thanks so much for your patience!

So Jetbeam's claim that there RRT1 can throw a beam of light 500 meters doesn't necesarily mean it has 250,000 lux at 1 meter right? It would have to have that to light up something a 1 m2 with 1 lumen but they could be talking about having a quarter lumen at that distance which might be enough to make a reflective sign "blink" back at you?

Do I have this theory right now?

2 flashlights that both put out 10,000 lux @ 1 meter would both be iluminating with an intensity of 1 lumen/meter2, 100 meters away right?

But if one of those lights put out 30 lumens and the other 900 lumens the difference at 100 meters away would not be the intensity of the light but the total area that was iluminated to an intensity of 1 lumen/meter2?
 

Gunner12

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Jetbeam could also be saying the maximum distance you can see a white wall when shining the light with night adapted eyes. You won't know how they get the number unless you ask them yourself.

Yup, it's right in theory. But as you can see by the lux figures posted here, lux at 1m is not an accurate representation (the Tiablo A10 has 21000 lux at 1m, but if you measure at a longer distance and then calculate the lux at 1m, you get a much higher number due to the beam pattern up close). Longer distance measurements and multiple measurements would be best for accuracy (but measuring once at 1m is an easy thing to do and doesn't require much space).

Either way, I think you are understanding everything correctly.
 

rickypanecatyl

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I tested my target bought, 140 lumen, "life force" flashlight the other day.

I walked 100 meters across a dark parking lot and shined it on my truck. At first I couldn't really see any significant light at all on my dirty, dark green truck but when the beam passed over the reflectors in the front and back the reflectors lit up strongly. As I strained my eyes I realized that there was a slight difference on the body of the truck when the light was on it (I could certainly see my truck without the flashlight parked in the dark).

My question is do you think the lighting I'm describing on my truck is more or less than 1 lumen/meter2?
 

Lighthouse one

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You are trying to buy a light with light figures that have too many elements to them. May I suggest you quit putting some much into numbers, and buy a quality light that gets good reviews. No one in going to buy only one light and never, ever need another. It's like you want to buy a car and only look at the HP rating.

The Trunite Catapult is one of the most powerful lights at a decent price out there....and you expect to find something better....1/2 the size? You're asking too much. THe Catapult needs the large size to handle the heat from the large power output.
 
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rickypanecatyl

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Some people prefer to have lots of different lights. I realize 1 light can not do everything well but that is what I'm looking for - the best all around light.

I never know when I'm going to need a light and flashlights aren't the only thing I need to be ready with. I usually carry with me 1 2CR123 size light and a couple small keychain size back up lights. If I need something different I can't run home and grab it - I would prefer to have 1 super high quality light that can throw/flood than many medium priced lights. Your right - I've probably put to much into this and I just need to get one, but the truth is I'm kind of having fun in my search of the best all around light :)
 
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