Why does Fenix lie about their lumen ratings and why are they able to?

[Turbo DV8]

Now if the power rating says XXX Watt RMS, then you're looking at something possibly interesting. If a manufacturer doesn't even bother to specify what kind of measurement was used to get the power rating, don't bother unless the manufacturer has a good name in car audio scenes.

You're right, but even an RMS rating is worthless without knowing the THD (and at what frequency) and dynamic headroom. Some cheap manufacturers can boast a huge power rating, but then the fine print says it is obtained at 10% THD. In other words, sure it puts out that power, but it would be unlistenable. Or, some other manufacturers can boast some very low THD number, but then the catch is it is only measured at 1kHz, or only measurered at certain volume levels which the particular amp can handle easily with low levels of distortion. And whatever happened to the dynamic headroom rating of an amp (dynamic power output), the single-most important spec which tells you how useable the power will be? You don't see this important rating anymore. These days you can pick up a "120 Watts x 5 channels" Sony receiver with one finger. That's because it has a wimpy power supply. My two-channel Kenwood KR-9600 receiver, made back in 1976, weighs twice as much as a Sony 5-ch amp because it has a real power supply capable of delivering some impressive current. It is rated at 160 W/Ch into 8 ohms, or 200 W/Ch into 4 ohms, both channels driven simultaneously from 20 Hz - 20 kHz @ 0.08% THD. It's dynamic power delivery @ 4 ohms is 375 W/Ch, or almost three dB of headroom. The "120 Watt" Sony receiver above is lucky to deliver 135 watts without clipping, and would probably fry itself if called upon to drive a 4 ohm load for any length of time. Your average Joe Blow buys an amp based on a power figure, period. Which is just as meaningless as a buying a flashlight based on just a lumen rating. I would rather have a 100 watt amp with 3dB of dynamic headroom than a 150 watt amp with a cheap power supply and virtually no headroom.

Sorry, I guess I hijacked this thread and need to find another forum!

 

[2xTrinity]

As the human eye isn't equally sensitive to all colors, a light than produces 100 lumen in color A can seem brighter or less bright than a light that produces 100 lumen in color B.

Lumens already take into account the different sensitivities -- a lumen is radiated power at some wavelength in watts, multiplied by a function that "weighs" each wavelength according to its sensitivity.

However, one point worthy of noting is that the lumens are adjusted to describe the brightness for daytime adjusted vision. Night vision however is more sensitive to the blue wavelengths and less sensitive to yellow and red, so a yellowish light in night-time conditions might appear dimmer than a bluer light of the same amount of lumens.

 

[Coop]

Sorry, I guess I hijacked this thread and need to find another forum!

Lol, Speak dutch? head on over to showyoursound.nl


let's get this thread back on topic...

 

[SpeedEvil]

Lie is a big word for this. There is no real standardmethod for measuring output. There are various units to express the properties of light (lumen, lux, candlepower) while these are all different, they are often used to indicate the 'ammount' of light of a flashlight. And measuring equipment/process is expensive (integrating spere and stuff like that). Therefore a lot of lumenratings are calculated. These calculated ratings are often based on optimal situations. Another thing to take into account is the color of the light. As the human eye isn't equally sensitive to all colors, a light than produces 100 lumen in color A can seem brighter or less bright than a light that produces 100 lumen in color B.

Umm, no.
A 100 lumen red light is just as bright as a 100 lumen green light, or a 100 lumen white light.
That's the point of the unit.

A light producing 1W of green light is much brighter than one producing 1W of white light (around 2-3 times, depending on assumptions on how white your white is), and that was why the lumen was invented, as otherwise there is no way of comparing the brightness of lights without both the wattage of light output, and the spectrum it has.

I would say that some tactics - for example quoting output before the reflector for example, are out-and-out lies.

I'd also go so far as to say that bare lumens figures, without details as to how you've measured them are almost as dishonest.

 

[Coop]

Umm, no.
A 100 lumen red light is just as bright as a 100 lumen green light, or a 100 lumen white light.
That's the point of the unit.

Yes that is true, but I was referring to the perception by the human eye. If the human eye is twice as sensitive to green light as it is to red light, a 200 lumen red light will look just as bright as a 100 lumen green light. I'm talking about perceived brightness, mark the magical words 'can seem' in my earlier post. While green/red is an extreme example, colortemperature can seriously affect the perception of brightness.

Lumens already take into account the different sensitivities -- a lumen is radiated power at some wavelength in watts, multiplied by a function that "weighs" each wavelength according to its sensitivity.

However, one point worthy of noting is that the lumens are adjusted to describe the brightness for daytime adjusted vision. Night vision however is more sensitive to the blue wavelengths and less sensitive to yellow and red, so a yellowish light in night-time conditions might appear dimmer than a bluer light of the same amount of lumens.

Uhm, are you sure about that?? IIRC, One Lumen is the total luminous flux emitted into a solid angle of one steradian by a light source with a luminous intensity of one candela. (Sciencebuffs correct me if I'm wrong ) The Lumen as a unit does not depend on day or night vision or the wavelength of the light, those things are variables and would completely beat the purpose of having a unit in the firstplace.
I think 2xTrinity might be referring to the ANSI Lumens which are used to measure the output of a projector...

 

[paxxus]

MayCooper, lumens is in fact perceived brightness - that's the whole idea.

http://en.wikipedia.org/wiki/Lumens

 

[3rd_shift]

The led's lumen rating is there, but not the light's as far as I can see.

Nuwai did the same thing with thier 75 lumen rated Q3 lights.
Most never got beyond 40 lumens in stock form due to the S*** ranked leds never being driven hard enough to get that bright (and that's pretty hard!)
Plus the plastic lense and the dark crenallated bezel absorbing some of the light.

With the bezel cropped down, stock circuit board bypassed for direct drive off of a lithium ion battery, ultraclear glass lense installed, and a U**K binned led put in there, then it could meet, or even exceed that lumen rating after all that fuss and expense.

Given time, Fenix may dig thier own hole just like Nuwai did.
Then another company and a whole flock of newer customers will show up and repeat the same above as has been going on throughout human history.

 

[Coop]

MayCooper, lumens is in fact perceived brightness - that's the whole idea.

http://en.wikipedia.org/wiki/Lumens

Paxxus, thank you for that information... I screwed up... Confused luminous flux with radiant flux... my bad I'm off from work and haven't been taking my ADD meds... Nice little eye opener to see why I should take those meds...

 

[SpeedEvil]

Yes that is true, but I was referring to the perception by the human eye. If the human eye is twice as sensitive to green light as it is to red light, a 200 lumen red light will look just as bright as a 100 lumen green light. I'm talking about perceived brightness, mark the magical words 'can seem' in my earlier post. While green/red is an extreme example, colortemperature can seriously affect the perception of brightness.

This is wrong.

The lumen is _defined_ as the brightness as percieved by the eye.
1 lumen of any colour, and of white of any colour temperature is as bright.

http://en.wikipedia.org/wiki/Lumen_(unit)

What changes is the minimum amount of power that is needed to emit that lumen.
For 1 green lumen, this is 1/683 (IIRC) of a watt.
For 1 red lumen, it's around 1/200th. http://en.wikipedia.org/wiki/Luminosity_function


A slight problem is that it's defined as the brightness of a light - to a light adapted eye.
In the dark, the function is subtly different - which is a slight error with flashlights, but not generally significant.

 

[MicroE]

Have you ever bought a shop-vac type of vacuum? Most of the manufacturer's rate the power of their units in "peak horsepower". The peak can only last for a second or two or the machine will fry itself or blow the fuse.

Or how about car engines. My Honda is rated at 200 horsepower, but only at maximum RPM. I never drive it at maximum RPM.

Buyer beware. In all things.

 

[BentHeadTX]

I have two flashlights that run T bin LuxIIIs at close to the same power level. My Peak Mediterranean 2AA pulls 825mA off two NiMH AA cells and my Peak Baltic 2xAAA penlight pulls 850mA from two NiMH AAA cells. Did a ceiling bounce test and the Med 2AA was brighter because the reflector is huge compared to the tiny Baltic AAA reflector.

Then there are optics, orange peel reflectors, pyrex, UVL, plastic and glass lens to throw in the mix. Us flashaholics know that the reflector type, diameter and depth make a difference.

The thing I want to know about a flashlight is the bin code of the LED and the power level it is driven. I can calculate mean average for the bin at that power level.

How are halogen bulbs rated? I think they are rated at the bulb so rating LEDs the same way is OK as long as it is labled as such.

Still trying to figure out "ebay lumens" the infamous gender bending 10,000 lumen 5mm LED 3AAA flashlight.

 

[EngrPaul]

Designed Lumens at the emitter. After a reflector and front glass, less. With production variations, who knows!

 

[whippoorwill]

I don't think Fenix inflates their ratings any more than most. I just take all of them with a grain of salt. SF is the closest to being truthful. And, as someone has previously stated, there are number of ways to measure and they take the best one. It is another facet of advertising that has to be taken in context.

 

[not2bright]

:huh2: Your statement is not correct. Why is it a lie, when a manufacturer like Fenix claimed the ratings of the manufacturer of the Led's?

Since there is no standard for the light output of flashlights for all manufacturers, there is nothing wrong to claim the rated Lumens-output of the Led before all the loss due to lens, reflector, heat.........

Long John, a manufacturer claiming that the output of a light is the same as the capability of the LED is at best misleading and at worst a lie.

Lumileds binswill produce X number of lumens driven at spec. Many of these lights are not driving to spec. Fenix does for some lights state the LED bin, for other manufacturers this information isn't given, but output claims are given based on an ideal bin driven to spec.

 

[SilverFox]

A while back I sent the lights that we are using for our light meter benchmarking to a lighting lab to be certified. I was amazed to find out that while there is a standard lumen measurement, there is no standard test procedure for measuring the output of flashlights.

I had to write the test procedure. It was review by the lab for any conflicts and we got good results, but there is no standard for this.

I was also amazed that some light manufacturers will instruct the lab to measure the candlepower of their lights in a way that inflates the numbers. Since there is no standard, the lab just takes the measurement and reports back to the manufacture.

How is this done? Keep in mind that light falls off with the square of distance. In theory, it is possible to take a reading at a distance and calculate back to what the reading should be at 1 foot (for candlepower) or 1 meter (for lux). Lights with reflectors columate the beam and often there is a cross over point in the beam where the light is highly concentrated. If you take the reading at the cross over point and calculate back to the standard distance, you end up with exaggerated numbers.

Now I understand where the 6 million candlepower claims come from...

I should also point out that even if there was a standard in place, the claims may still be off. Look at batteries...

Tom

 

[greenLED]

The issue of inflated numbers is not exclusive to output; look at the runtime estimates given by some manufacturers... :green:

 

[Long John]

Long John, a manufacturer claiming that the output of a light is the same as the capability of the LED is at best misleading and at worst a lie.

Lumileds binswill produce X number of lumens driven at spec. Many of these lights are not driving to spec. Fenix does for some lights state the LED bin, for other manufacturers this information isn't given, but output claims are given based on an ideal bin driven to spec.

Your statement is not correct.

Where does Fenix claim, that the output is the same as the capability of the LED?

Take a look to the Fenix homepage.
http://www.fenixlight.com/flashlight/index.htm

You will see the L0D is the only light on this site with a stated Lumens, 30 in this case. But it's a T-bin LuxIII, so take a look to this site:

http://home.comcast.net/~theledguy/bin_codes/index.htm

You will see, the T-bin is rated for 67.2-87.4. So what's wrong with the claimed 30 Lumens max. in this case? Where does Fenix claimed, that the Led is driven at specs? It's an underdriven Led in this case, so there is nothing wrong.

Take a look to this site:

http://www.fenixlight.com/flashlight/fenixp1d.htm

It's a P1D with a LuxIII T-bin. They claimed 70 Lumens max. The Led is capable to deliver 67.2-87.4 Lumens under optimum conditions, driven at specs. Nothing wrong IMO. On the contrary, I like it very well, that Fenix claimed the binning of the LED's in their lights.
I.e. Surefire doesn't do this. In the case of the i.e. L4 they claimed 60/100 Lumens but nobody knows, which binning is build in. Is it a V or W-bin?

Do you know the driving level of the Fenix P1D at the Led? Do you have the chance to measure the Lumen output of a light in front and behind the lens?
I couldn't found any claim of Fenix, that the claimed Lumens should be in front of the light or directly at the LED.

I guess, they took the datas from Lumileds without measuring the real output.

For me, the best solution would be, claiming the Bin's and the driving levels.
In this case we wouldn't have such a useless discussion.

But it's not right to accuse Fenix as a liar.

Best regards

____
Tom

 

[joema]

Long John, a manufacturer claiming that the output of a light is the same as the capability of the LED is at best misleading and at worst a lie...

It's no more a lie than a car mfg claiming x horsepower, and you assuming it means rear wheel hp, then saying they lied, your car won't actually produce the specified hp when you tested on a chassis dyno.

At least in the hp case, the SAE standard specifies crankshaft hp, but this isn't spelled out in advertising -- you just have to know that. With lumens there's NO standard that specifies "lumen" means final output lumens vs bulb lumens. In the current situation, when a mfg says "lumens" it can mean almost anything. Now -- IF they claimed x final output lumens, and further claimed that every specimen off the assembly line meets this, and also specified how to reproduce the results, THEN they're lying if your unit doesn't, IF tested under those conditions.

While there's a scientific definition of lumen (1 candela per steradian), it's not defined in terms of the flashlight you actually receive.

Compare this to mechanical horsepower (lumens are roughly like optical horsepower). Like lumens there's a scientific definition of horsepower: 746 watts. Unlike lumens, for years there has been detailed published test procedures for testing horsepower, and the test standards have been refined several times. In the U.S, SAE gross hp gave way to SAE net hp in 1972, then was most recently updated in 2004.

The SAE gross hp allowed for running the bare engine with no accessory drives. Even the SAE net standard had loopholes. It didn't mandate gasoline octane, or that the engine be full of oil, or the ECU have production software, etc. Certain manufacturers exploited these and it bumped their hp ratings a bit. http://www.detnews.com/2005/autosinsider/0508/17/A01-283759.htm

This resulted in a more rigorous test standard (SAE J1349 rev 8/04), plus an additional new SAE standard for "certified horsepower" (SAE J2723). The latter requires an independent witness during the test.

http://neptune.spacebears.com/opine/horsepwr.html
http://www.roadandtrack.com/article.asp?section_id=18&article_id=2814

So even with the SAE hp test standards, there is often consumer confusion and manufacturer exploitation of loopholes. With lumens, there's not even a test standard.

There's a common misconception that advertised hp or lumens is a guarantee your specific item will produce that. Unless the specification itself or some standard says this, there's no guarantee.

Think about it. In any mass produced item there will be production variation. What does a hp or lumen rating even mean? That a prototype produced that? Or did the mfg test 10 units and take the best number? Or did they test 100 units and take the arithmetic average? Or the arithmetic mean? Or did they plot a bell curve and verify every light is within one standard deviation? If so, how? Test every unit? If the exact test procedure AND the method (if any) for ensuring production uniformity isn't specified, there's no guarantee your item produces the specified output.

You say: "I don't care, I just want my light to produce that", or "they should just do the right thing". Fine, except there's no governing body to define what the "right thing" is, nor a body to police and enforce that. If there was, many small mfgs would simply shift from lumens to a non-policed unit, or drop the ratings entirely.

HDS supposedly hand calibrates each light to ensure it meets the specified lumen output, but you pay a price for that.

 

[Dark Mower]

The worst case would be to have all manufacturers rate their light at what could be the output of the emitter. Every light of the same specs would be rated exactly the same ! Then a modder would overdrive the LED and the spec would still have to be the same. In the real world there are variations. Horsepower for engines are more realistic when rated in net numbers, in real use- mated to a transmission, belts, alternator, water pump not gross horsepower, freewheeling. The true output of a light stuck in a reflector/optic and behind a piece of glass is much more honest then the output of a best case hypothetical emitter tested by the emitter maker. Admittedly, the real numbers are tame compared to the bragging numbers but they would be real. Fenix is not doing you any favors by inflating the output numbers.

The value of Fenix would improve if they were honest.

 

[tron3]

Well, after comparing my 135 lumen P1D-CE with my other 120 lumen rated lights, I must say it holds its own - if not brighter.

Are they all lying, or is it really brighter?