Why Lumens?

[ViReN]

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Assumption: A Light of Point Source, Emitts 60 Lumens in All Directions in the Intigrating Sphere.

We take this Light Source and put it in inside a Reflector (like IMS20 mm) / Optic (like faren)

We Again Perform the test in Intigrating Sphere with the above said setup... What will be the Lumen Output ? Yes... we have to forget the Lumen Defination this time but I am curious what Output will the "Lumen Meter" Show ?

If the "Reading" is around (60 - (Losses in Reflector + Lens)) = 50 Lumens .... then I can understand "Why Lumens" part... Else...

We need a New Defination of "Total Amount Of Light" in a Specific Direction as an output of a "typical" Flashlight.... (not just throw... not just Lux)... We have to consider Hotspot, Side Spill along with Throw & Lux @ 1 Meter for such a defination for sure.

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[The_virus]

I pay more attention to lux readings myself. Lumens is like horsepower as someone already mentioned. In a flashlight, that means how bright the bulb is, but only if you were to look at it directly. Take Roy's example of a Maglite in candle mode. A 10 lumen light will be kinda dim, whereas a 100 lumen light would probably be painful to look at.

Lux readings are more of a "user perspective" of the blub. As the same person mentioned...quarter mile times. You get a reading of just how much of the power is going where you want it. Regardless of the lumens, if the flashlight is efficient and well designed, you'll get a good lux rating. It also tells you roughly how bright your central spot will be. If the flashlight is a piece of garbage and the reflector sits too far forward from the bulb, you could get a significant amount of light wasted, reflected back into the battery compartment. A lux reading would reveal this, a lumen rating would not.

To take an extreme example, imagine a flashlight manufactured with no lens, but a bulb inside a sealed hollow aluminum head. It could be marketed as a 1000 lumen light and it could be true, but a lux reading would tell you more (like if the lux reading was zero) about the light's usefulness from a user's perspective.

Spots and floods will give varying lux ratings, as the power of the light can be concentrated like a lazer, or spread out like a floodlight. This is where a beamshot is more useful.

In my opinion, a lux reading paired with a beamshot is all I'd need to choose a flashlight. A lumen reading as well could be helpful, but I'd consider it extraneous information.

Oh and as a brief side comment...about the LuxV's not throwing...I'd compare LuxV's to a wild horse. They are a relatively new invention/discovery, and the power is there, we just haven't found a way to harness it. /ubbthreads/images/graemlins/wink.gif

 

[Dr_Joe]

[ QUOTE ]
SilverFox said:
When I think of lumens, I think in terms of raw power. I think of horsepower the same way.

When I think of lux, I think in terms of performance. Kind of like quarter mile times.

Lumens gives me an idea of the possibilities, and also some idea of the power needed. Lux tells me how that power has been put to use.


[/ QUOTE ]

I like this analogy. A 400 horsepower engine in a 2000 lb. car performs very differently than the same engine in a 10,000 lb. truck.

Think of taking an Aleph with the same light engine, and changing the heads from Aleph 1 to Aleph 2, and then Aleph 3. The lumen rating of the light engine shouldn't change, but the beam shape, throw, and lux will change significantly, right ? /ubbthreads/images/graemlins/thinking.gif

I like to think of Lumens as a light source's potential, and Lux and beam-width as a measure of what a flashlight is doing with that potential.

Whoever said you can't make a Lux-V throw should come play with my Space-Needle II /ubbthreads/images/graemlins/grin.gif (thanks Mr. Bulk !)

 

[VidPro]

BOTH
A Waste Spot:
it doesnt mean crud to me to know something had 18billion mcd, if at 50 feet its the size of a quarter

Thats a Lantern Not a Flashlight:
and in a flashlight if it has 1700 lumens but its 360 degree output , that is a Lantern , not a flashlight.

Dont be Swayed by Unreal Specs:
If they list lumen OR mcd specs , and they are the components, but not HOW the components are USED, or how they work after it has been on for 10 minutes, then thier specs have no value to reality.

SPOT Everything
if there is SUFFICIENT light at the distance that you want it to work for, the next best thing you want is a larger area being lite up.

Undue Spotting for High Specs in Adds
as far as headlights, and some of the lights out there with a magnifyer on them sending the light to a SPOT, it doesnt always improve the ability to SEE with them. it might improve the ability to see the neighbors 12 blocks away.

Off the Charts (in ONE area) :
when manufactures make a light a nasty useless spot, so they can be on the top of a spot measuring scale, even though they have similar overall output, it will all depend on how the users view or NEED that information.
If we FEED off of ONE type of measuring, they will feed us back ONE type of light.
that would mean everything will become a concentrated spot, which might be great for a helicopter with a search light and a lazer beam, and a light saber.
we will end up with pocket key lights, with laser outputs.

and the reverse, if its all about just output, we will end up with raw emitters with no optics, or effort put into a nice beam.

Need to Know Light Output:
Spot meteting aint everything, when your NOT SPOTING its NOTHING.
the actual total light of the output has ALL the value when your LIGHTING an area, not spotting.

Conclusion:
keep ALL the specs,
expect truth in the actual outputs, to be reflecting its actual use.
Improve the ADJUSTABLE beam so it will spot and Flood correctally, then total output of the source is all that is going to count. with the right light, if you want wizz bang super spot, you would just focus it down to one point. the rest of the time, you could light up what you actuall SEE with your eyes.
or
put enough POWER in it, that the "SPOT" is bright but shows more than a field mouse.

again, the reviewers information is complete, and i hope it stays that way, untill seeing pinheads in your neighbors house has value
the METHOD of measuring total light, and spot light is 100% effective if the SAME thing is used to measure each, no mater what fancy names and calibrated junk are used to do so.