Explain this to me, lux and lumen.

[Cappie]

I found this page that compares and reviews alot of ledlights,

http://www.light-reviews.com/reviews.html

and you can sort the list on LUX so you get the highest one on top, etc.

If you do that you can see that the,

RaidFire Spear LUX RATING : 24900

had an incredible amount of lux, more than 3x that of the,

Fenix TK10 Q5 LUX RATING : 7070

and if you check the specs for these lights you can see that the Raidfire has 250 lumen and the fenix has 225 lumen, not alot of difference but still the lux output is 3x higher?? Why is that, is it just cuz the reflector is wider that it produces more light output?

the pricing on both are roughlty the same, so why would anyone ever opt to go for a fenix over a raidfire spear?? The more light the better right?

 

[Dodge]

I'm sure someone will be along with a more technical explanation soon, but basically lumens = total output, lux = max brightness.

So a light with a pencil-thin beam will have many more lux than one with a floody output, even though their total lumens may be the same.

 

[Marduke]

Lumens is a measure of the total output, Lux is basically a measure of the intensity of the center (hotspot) of the beam. Higher lumens means a brighter light overall, higher Lux means the light has more "throw", or the ability to project the beam further. Usually a larger reflector makes the light throw better.

 

[Brownstone]

Like others said: Lux is the maximum brightness, Lumens are the total light.

Imagine a laser beam: Very bright on the spot that it hits, but not a lot of total light. Hi Lux, Low Lumens.

Now imagine a house lamp with a 25 watt bulb lighting a room. Not particularly bright anywhere, but because light is everywhere the total output is high. Low Lux, High Lumens.

A flashlight that has a tightly focused hot spot with little spill would have high lux, but might have low lumens. We call lights like this "throwy" because they can throw light a long way.

A flashlight that has a very wide smooth beam without any hotspot would have low lux, but might have high lumens. We call lights like this "floody" because they can flood an area with light.

Most lights have a combination of throw and flood. Some lights are focusable between throw and flood.

 

[HKJ]

One way to look at this is to compare it to a lake:

Lux: The maximum depth of the lake.

Lumen: The total amount of water in the lake.

Edit:

Lux could be the depth anywhere in the lake, but who wants to know anything but the deepest place and the same with lux, only the highest lux value is specified.

 

[Cappie]

Ok thnx for clearing that up, so the Raidfire is actually a very nifty flashlight cuz its got a very high lux and very high lumen? Does anyone here own one?

I love ledlights, eversince I bought my first not too long ago, it was an Inova X0, not the best out there but it throws a decent amount. After that I bought an Olight T-20 military edition, and just yesterday I bought one of these little tiny Fenix P1 CE Cree Q2 that has like 90 lumens, 3x as much as my bigger Inova one.

BTW are there lights out there that are like 400 lumen that don't cost too much, ledlights I mean, all I can find so far are things that cost 250-300€ and thats a bit too pricey for my sake.

 

[kramer5150]

:thumbsup::thumbsup::thumbsup:

Its one thing to be knowledgeable about something. Its quite another to be able to explain it in simple terms so anyone can understand.

Thanks gents!!

 

[2xTrinity]

I can't believe nobody has said it yet:


Lux = lumens/sqaure meter.

Actually a measure of light incident on a surface, NOT beam intensity. Most of the time a flashlight manfufacturer talks about lux, they actually mean lux @ 1 meter distance.

Lumens - radiated power weighted by eye sensitivity to the emitted spectrum.

Overall output weighted by how bright it looks. eg, a UV LED is zero lumens no matter what its output is, because it is invisible. Colors the eye is more sensitive to appear brighter, and thus count for more lumens for a given amount of radiated power.

Candela - Beam intensity, basically lumens/beam-angle. IF your light is a perfect point source, intensity in candela is equal to Lux @ 1 meter.

 

[Gunner12]

The above posters have explaned things well so I'l get to your next question.

Most LEDs right now can hit 250 lumen within spec.

The Seoul P7 can hit over 500 lumen within spec but it will need a larger reflector to throw further.

There are also multi LED lights that will get over 400 lumen but the also won't have a throwy beam.