led lumens

ok i have a ? it fenix t1 has 225 lumens at the emitter then what does the surefire l4 have at the emitter ?

Testing on CPF has shown that 225 is very close to torch lumens for the T1

anybody have an answer

It can probably be calculated more accurately if one knows at what current level the emitter is being driven, but a rough optics loss caluculation gives 154.

L4 is not an optic it's a reflector system.

www.surefire.com says L4 has a max 100 lumens output for 2.5 hours.

scaredofthedark said:

L4 is not an optic it's a reflector system.

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"optic loss" is also a generic term for reflector + lens losses

well that's a misnomer isn't it...

Not really. "Optics" can refer to any system that focuses, bends, or directs light. Inova's TIROS (total internal reflection optical system) may have led to TIR setups being called optics. Basically, if it messes with light, it can be said to be an "optical system." We flashaholics like to simply call TIR systems optics and reflector based systems reflectors.

but those internal reflection setups use an actual lens, which refract light inside it.
calling a reflecting system an "optic" is just wrong


sorry to eric for hijacking your thread but i believe 154 to in the right ball park

scaredofthedark said:

but those internal reflection setups use an actual lens, which refract light inside it.
calling a reflecting system an "optic" is just wrong

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I nominate this for Nitpick of the Year. :thumbsup:

Don't forget, the actual LED emitter is encased in an housing through which there is some amount of refraction. So your refracting, reflecting, and passing through a lens. Qualifies for optics in my book :naughty:.

well you got me there...:thumbsup:
but i consider the emitter the source, and not part of the focusing system

i just feel a bit argumentative today i hope i don't **** anyone off

lol, if you're trying to compare lumen figures across manufacturers, don't even bother. The TK10 will probably be brighter, but by how much it's hard to say- surefire lumens are notoriously underrated OTF lumens, where as fenix lumens tend to be emitter lumens according to the manufacturers spec. sheets. The exception to this is the TK10, which apparently has ppretty clsoe to 225 lumens OTF.

honestly, i dont think Any light now adays from any of the manufacturors present here at CPF suffer from significant opitcal losses. Firstly, they all have anti-reflective coating on lenses...and they all have pretty decent reflectors/optics.

wouldnt it be awsome, is every single member chipped in USD$1 and we bought a Intergrating Sphere to be kept with Greta (with her approval of course) so that every new light that comes out, the manufacturor sends her a unit, and then we can have solid CPF lumen numbers...and manufacturors can have something like "CPF approved" lumen claims...it would be a whole new standard!

Crenshaw

Crenshaw said:

honestly, i dont think Any light now adays from any of the manufacturors present here at CPF suffer from significant opitcal losses. Firstly, they all have anti-reflective coating on lenses...and they all have pretty decent reflectors/optics.

wouldnt it be awsome, is every single member chipped in USD$1 and we bought a Intergrating Sphere to be kept with Greta (with her approval of course) so that every new light that comes out, the manufacturor sends her a unit, and then we can have solid CPF lumen numbers...and manufacturors can have something like "CPF approved" lumen claims...it would be a whole new standard!

Crenshaw

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point 1: When you say significant, what do you mean? Apparently the L2D has been tested to have about 80% optical efficiency (which surprised me)

point 2: That'd be great. I'm in

Jarl said:

point 1: When you say significant, what do you mean? Apparently the L2D has been tested to have about 80% optical efficiency (which surprised me)

point 2: That'd be great. I'm in

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Significant- loss in the order of tens of %

typically, Losses are estimated as 30%...which seems unlikley to me when i look at the Lenses of my lights, i sometimes have to poke them to make sure they are actually there..lol

the L2D is tested to have 80%? thats surprisingly high losses, i guess my guesses are off then..heh..

Crenshaw

Crenshaw said:

the L2D is tested to have 80%? thats surprisingly high losses, i guess my guesses are off then..heh..

Crenshaw

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L2D has 80% efficiency, not losses

yeah, what i meant was the 20% loss is surprisingly high to me....haha, 80% losses is ridiculous..should have worded that better..

Crenshaw

Crenshaw said:

wouldnt it be awsome, is every single member chipped in USD$1 and we bought a Intergrating Sphere to be kept with Greta (with her approval of course) so that every new light that comes out, the manufacturor sends her a unit, and then we can have solid CPF lumen numbers...and manufacturors can have something like "CPF approved" lumen claims...it would be a whole new standard!

Crenshaw

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It would be easier and cheaper to establish a fund to pay a test lab to produce a basic output runtime chart of flashlight.

If measuring the output of a flashlight was simple, easy and quick 'everybody' would be doing it. As it is there very few test labs, even those with almost the right equipment, that offer such a service.

The trouble/problem/issue I see is that things are not as simple as just shoving a flashlight with fresh batteries into a sphere and taking a lumen reading.
Establishing an acceptable test method/procedure that gives a representative performance rating is difficult enough - worse is that even a simple procedure in my opinion would require in the order of five samples of each flashlight, each subjected to at least one output/runtime test, perhaps more depending on any degree of variability discovered.
It would be tested with the manufacturer's stated batteries, and at least once with a control brand, and then one of the five flashlights would be subjected to at least ten battery cycles and tested again - depending on any degredation discovered more samples would also be tested.

It goes on and on - all in order to ensure any rating is representative...

Al

hmmmm, thats probably a better idea then....SO......anyone got access to a light lab?

Crenshaw