Lumens exaggeration
 

We have seen manufacturers tend to exaggerate the lumens of their flashlights (DX and elsewhere). But do most exaggerations apply to just the higher lumens? For example I've seen reviews that said an 1600 lumen flashlight was actually only some 300 or 500 lumens. What I wonder is, if the manufacturer claims a light is 500 lumens, is it closer to the fact, instead of the light being actually 100 lumens? I'm getting frustrated because I paid nearly $30 for an "800 lumen" light, then saw another, "1800 lumen" light for less than $20. Should we trust the cost difference (more $$ = brighter?) rather than the lumen claim difference? :notamused:

I'm no expert, but it's my understanding that a single XML T6 produces ~1000 lumens under ideal conditions. Capacity of the power supply (batteries), reflector, even ambient temperature will factor into what really ends up coming out.

I've got a DX light that claims 510 lumens. Got no idea how accurate that claim is, but the sucker is bright.

I think the real question is: "What is a reputable seller?"
Personally I look at product warranty, return policies and costs and what international standards are referenced. Many international sellers are counting on the fact that return shipping will cost as much or more than a product is worth so ..... even unhappy customers won't return anything.

For example - the last batteries I bought were from a seller within the country and came with a two year warranty - in spite of being an item on clearance. If there's an issue they'll be replaced with an equivalent or upgraded model.

This is part of why I avoid buying these on ebay.

Vendors with established sites or Amazon accounts get to build up a reputation of their own or for their lights. Some of the better vendors, like fancyflashlights/cnqualitylights, have responded to requests to check current draw on their lights. The provides a very good indication of actual light output. They also tend to post more pictures, particularly those of the beam. Some sites like DX even has reviews and comments, which really helps provide notice if the quality of a particular item changes over time. This allows me to play it safe unless I try to be an early adopter. Even so, being an early adopter is pretty safe when dealing with a good vendor that provides beam shots, current draw, and their own impressions. Some of the worse vendors like dinodirect, for example, responded to a post for pictures showing a SST-50 label on their reflector, but everyone got lights with XM-L labels on the reflectors...they were XM-L.

With ebay, the sellers often sell so many different items that it's tough to tell if they're slipping in a bad product. Not to mention the pressure to give good ratings, and that those ratings are for the seller, not the product.

Finally, it's good to participate in online discussion about these lights. This forum is good. So is budgetlightforum. At blf there's a forum just for vendor feedback. It's not like cpf where your posts will get deleted or you'll get banned if you write anything bad about a contributing vendor or manufacturer.

Can you point me towards a lumen test that compares claimed lumens?

The only one I've ever seen was on MTBR, but they seem to have taken that down, and now only publish measured lux. There's a video showing how they got measured lumens (with the collecting sphere), but again, I can't seem to find those results published anywhere on the site, even though I swear I saw them pop up a couple of, or three, weeks ago.

Maybe they found there was a critical flaw in their test; the collecting sphere did seem small to me, but I don't know much about these things, and can only speculate as to why MTBR took the results down in any case.

It does bring up the question, however, of what type of lumen measurement testing is being done when we see manufacturer claimed lumens. For example, are they actually reporting the headlight itself, or just the emitter under some other operating circumstances. Temperature, current, and placement of the light source in the collecting sphere are all variables that need accounting for before lumens can be effectively compared.

Of course, that may be the very reason MTBR dropped their lumen measurements; they simply were not indicative of anything useful. Certainly lux, if measured properly, as an intensity of light at a given point, could be more helpful to the consumer, particularly because theirs is the only measurement, and avoids the messy aforementioned business of lumen comparisons and of course, gives some measure of actual usable light output at a given distance.

So, I've heard people talk about "lumen exaggeration," but where is the proof (data) and even then, without knowing where those lumens are coming from (actual lamp assembly or emitter) and how they're measured, we can't really make any meaningful statements such as some are overrated.

Certainly standardized testing and measurement protocols for the actual headlight manufacturers is needed, because MTBR can't test them all!

Most manufacturers do claim XXXX lumen output. I believe, as you appear to also, that they aren't reporting the actual output but the ideal output based on manufacturer specifications which are probably based on calculated rather than actual measured output. The 'out the front' light is probably lower than the calculated amount but, because nearly everyone lists the same way, valid comparisons can be made as long as you don't get too hung up on the actual numbers.

The MTBR light measurement method that I have seen is to sit the light on a bench pointing towards a ceiling with a light meter next to the light, then measure the lux from the reflected light of the ceiling. While this probably isn't the best method, at least it's a consistent measurement. I wouldn't say that you or I could reproduce the measurement but for a comparison within their results, it's valid.

We also have to take into account the construction of the lamp. A Magicshine might be putting out the same lumens as the Cree I bought this summer but the Cree has a narrower beam. The narrow beam makes the perceived light brighter because the lux is higher. We really should report lux but even that has its own problems. Without specifying the distance from the source, the lux is meaningless for comparison.

It is a known fact that they jack up the lums. However, I don't believe that are 90% off.. :)

Example, my favorite light is the Keygos M10a.. That baby is rated at 1600 lums. Okay, I know that baby is pushing more than 1000, I know not 1600, I think, but it is over a 1000. For me, that is a good bang for the buck..

Also, would be nice for you to get both of those lights, I bet you will find out the answer then. My money would be on the cheapee to be the winner. ;)

The test lumens of each individual lights are still listed under each light. There is no chart or listing that show them all in one chart beside the ceiling bounce lux test. However, if you selected an individual light and click on the review, there is a heading that list the lumens tested for that particular light. Some of the light cannot be tested because of the opening of the Sphere. The larger housing or oval shape light are the one that the light cannot be inserted into the sphere opening for test. As cyccommute stated, they do test all lights they have using the ceiling bounce test and measure under the lux unit. What they are doing is using an enclose enviroment such as a room to simulate the sphere. Most of the lights are bounce off the ceiling and adjacent wall and the meter measure those lights. Although not as accurate as a sphere, it does allow for all light unit to be tested and does give a relative comparison if you are comparing one lighthead unit to another for total light output (not peak throw).

Truth is the fact that the XML can only output 900 to1000 lumens if driven at maxium current of 3 amps. This fact is from the Cree Data Sheet.

I have the Keygo M10 light myself. In my sphere test, the Keygo does not give out any more than those light that are Ansi FL1 rated at 850 lumens. I test it against my Jetbeam BC40 in my DIY IS Sphere and the meter reading was about the same. What makes it appears brighter than 1000 lumens is the throw factor which the Keygo reflector is good at doing. It does have a good throw at 25K lux @ 1m. The reflector makes a heck of a difference. For example, if you take the lens and reflector and just shine the bare LED out the flashlight, the beam will appear very little like if it was 500 lumens or less, however adding back the reflector makes it appear much more because there is much less wasted lumens spilling all over everywhere.

Infos on UR DIY IS, please?

Oops, sorry for the acronym. This is the second time I used acronym and it got others questioning the meaning. DIY IS is: Do it yourself Integrated Sphere. Over the summer I took on a science project while I was bored. I made a IS (integrated sphere) by using a 14 inch Jolly ball. I cut it in half and painted it flat white with several coat of paint. I was hoping to get some Barium Sulfite (spelling?) powder and coat the interior to enhance the accuracy. Stuck a light holder made from a dial caliper holder and place it on a training stand. I used several lights that were tested by the Ansi FL standard and by various reviewer from CPF and use those numbers for my correction factor. The final product looks like some out of this world or as one other member quoted "popcorn maker". Anyway it looks like this with a Zebralight SC600 being tested. Anyway, I test a lot of light from my addictive collection. It may not be very accurate but for relative testing and comparison, it helps. It is interesting to see just how little or how much each manufactor of flashlight and bicycle light varies. There are only a few that actually claim what the light actually gives out within whatever accuracy of this DIY IS. So far, company like Gemini, Gloworm, and the Ansi FL rated flashlight came out pretty close while the Ebay and DX stuff was way off.

1000 lumens at 3 amps requires better cooling than most lights have. You can still get 1000 lumens with more current though. A lot more current.

http://budgetlightforum.com/node/2603

http://bikeforums.net/attachment.php...hmentid=283637

With the same current, you can get many more lumens by mounting the LED directly to copper. About 300 lumens in this case, with even more at higher current.

http://budgetlightforum.com/node/10267

http://bikeforums.net/attachment.php...hmentid=283638

These results has me wanting to buy a lathe.

Thanks for that info. Didn't someone over at CPF had something like custom made copper bonding for the LED instead of star which he uses for his custom flashlight? If so, I wonder does he sell them. It would be fun to play around with using drivers that are 3amps and higher.

A question about the XM-L T6 LEDs. Are they used as a single LED or as an array? Obviously, they aren't being operated at single LED at 3 amps. A more likely current draw is around 1.5 A or perhaps even around 1.0A. From the sheet, that puts the lumen output from around 550 lumens to 380 lumens. If you are operating an array of diodes, wouldn't that get the lumen output closer to the advertized level.

I've owned Magicshine 900, the 1000 and now Cree LED lamps that have noticeable differences in output. I've run them all side-by-side and there is definitely a difference in intensity.

I just want to have an idea about the lumen measure: Does anyone have idea how many lumens the Radbot 1000 have approximately? below or more than 50? And how many lumens does an average car headlight have?

the XM-L is a single LED that has like an array of LEDs on the chip. The data sheet says it IS rated for 3000mA (which is 3 amps) at 3.3 volts, aka 10 watts (3.3V * 3A == 10 watts). The XM-L lights I've seen have 1 2 or 3 of these, for < 1000 lumens, <2000 lumens, or <3000 lumens.

the cheap noname chinese ebay lamp I have gets very very hot on its 'high' setting, which is IMHO insanely bright, but its low setting is about 1.5 stops dimmer (1/3rd as bright) and the lamp just gets barely warm. I have the action led spreader lens on it, and even on low its way plenty of light for road riding. the bright setting would be totally blinding to oncoming cars, even if its aimed down at the ground. I compared it with the H4 80/100 watt in my motorcycle (stock H4 is 55/60 watt) and this chinese cree lamp is brighter, even when spread . I just wish it had a clean cutoff.

I think it would be cool to try and put one of these LEDs in a Hella MicroDE projector fog lamp and see how that works. the MicroDE is meant for a 55W H3 halogen bulb (there is also a HID driving light version, which is a spot pattern rather than a fog spread)

We smoked the inside of ISs with MgO by burning Mg strips. IMO, this is superior to most other methods due to independence of reflectivity/scattering on angle of incidence achieved by the small size and powdery nature of the particles deposited. Perhaps newer coatings may be nearly as good depending on method of application? Naturally, with burning Mg, due caution is required.

I think member pierce is correct. The XML is a single LED on a die with an array that are link together. You can see about 6 of these arrays where each one is a rectangular shape. Unlike the older MS900 P7 where the P7 have 4 LED place on the die, the XML looks like maybe 6 arrays of LED. Not sure if what I stated is correct but someone who is more knowlege may provide a better answer. I posted a picture of the LED while it is lit up. You can see the six row that are separated from each other.

The MS900 P7 is only about 500 lumens out the front and has a much greater spill. The XML in most lights gives out about 700 to 850 out the front lumens. The hot spot and corona is much more intense making the lights much more useable and brighter.

http://i1127.photobucket.com/albums/...c/DSCN0025.jpg

Wow, then maybe I will have a "popcorn maker" :)

Thanks for the warning.

I'd go by this simple rule of thumb: Chinese output levels are always exaggerated. You get what you pay for. Stick to U.S. manufacturers.

Cree might be based in North Carolina, but they have a very large LED chip making operation in China. I'm pretty sure most all of your 'US Manufacturers' are in fact outsourcing the actual manufacturing to China, otherwise their prices would be way more expensive. I paid under $40 for my chinese Cree XM-L T6 lamp from ebay including postage from Shenzen... I knew up front the advertised lumens were impossible (1800 lumens is the absolute peak light you'd get out of one of these LEDs just before it fries). If it breaks, oh well. Yeah, I could have spent $200 or something on a Nite-Rider system. hmmmm.

btw, "coleen c" mentioned 'lumens out front'. Lumen is a measurement of the total amount of light emitted, it is NOT how bright something is at any specific point (thats 'lux' or 'candela').

the projection pattern of my XM-L T6 lamp is almost entirely a function of the reflector+lens assembly its mounted in. With the lens and reflector removed, there's ~90 degree wide cone of even light (and it probably would be closer to 180 degree but the housing occludes it), the edge is just about as bright as the center. either way, the same number of lumens are emitted by the LED (arguably, with the reflector more lumens come out the front, as without the reflector, a significant portion is absorbed by the sides of the housing).

I was referring to the light manufacturers and not the LED emitter manufacturers. Of course U.S. manufactured lights are more expensive, but they're higher quality and they back what they sell. A couple of examples are DiNotte and Jetlites.

I just want to say, colleen c, you rock!

for the $170 a DiNotte XM-L light costs, I can buy 4 of these Chinese XM-L lights. Jetlite's equivalent light appears to be $229 (on sale for $199 but out of stock?).

my BIKE cost me $350 (last year's dealer demo of a Globe hybrid, got a great discount). I'd be insane to put $200 lights on it.

I guess my question would be "Why would you want to do this?" You really haven't changed the Cree specs of 100 lumens / watt - rather you simply demonstrated that their recommendations make sense. You didn't get a 2,130 lumen output which is what would have been needed to maintain a 100 lumen / watt output, and by disregarding the specs, you undoubtably caused a color shift and seriously shortened the LED life expectancy. This LED was designed to be used in arrays for applications requiring high light outputs and you actually simply confirmed that you could have gotten more lumens with the same amperage simply by using two emitters instead of one.

Look closer at the results. With your LED on an aluminum star that's on aluminum, you're not going to get within 30% of the specs. Putting the LED directly on copper gets a lot closer to the spec. So my question is "Why wouldn't you want to get an 30% more lumens for the same power output?"

As I said earlier, if you're not going to do your research, use good vendors and won't do math, then you take a big risk when buying Chinese lights. If you're willing to put forth a little effort and do some simple math, you can get a LOT for what you pay for.

The actual lumens to dollars ratio with Chinese lights is very hard for US lights to match.

Due caution is indeed warranted if you are going to burn magnesium to make MgO. If you have never done it, it is an extremely intense fire that, once started, is almost impossible to put out until the metal is consumed. It burns very hot and with a very high UV flux.

I think you both misinterpreted my question. Looking at colleen c's picture, is each LED in the array a discreet LED with a discreet output or is the output measured for the whole chip? It is unclear to me, reading page 2 of the Cree data sheet that colleen c linked to, whether the output is measured for each LED in the array or for the whole device. At 700mA, they say that the lumen output for an XM-L T6 is 280 lumens. If the whole chip is the "LED", then would the total output at 700 mA be 280 lumens or if each LED is putting out 280 lumens at 700 mA, the total light output would be close to the 1800 lumens listed by some manufacturers.

Like I said above, I've run the 900 and 1000 lumen Magicshines next to the Crees I have. The Cree has a narrower beam but they are far brighter than the Magicshines. They seem too bright for the reflector to be the only reason for the output.

This is a very important, because you have people running around talking about how they can tell lumens by sight. Sure to some extent it's fair to say that a brighter light is putting out more lumens, but to then jump to the conclusion that someone is lying to them, usually the Chinese. On top of that, none of these folks have any idea of how the reported lumens were measured, and therefore don't know if any exaggeration is really going on.

None of which is to say that some sellers aren't deliberately and maliciously overstating their products; I'm sure there are. However, I think there is plenty of likelihood that testing variance, bench results as opposed to application results, and production variables could, any one of them, explain differences between claimed and actual results.

Again, I understand the position that producer statements should match up with consumer expectations in some way, and ideal world/optimized/theoretical max lumen outputs don't serve that goal well, so I'm all for industry standards of some sort, ideally real world/actual application testing.

Maybe the proof of widespread lying and deceptive practices is out there, but I don't think I've seen it yet, and it feels un-American to me to presume guilt, and doubly so without any evidence to the contrary.

Oh, and thanks, Colleen, for pointing me back to the MTBR tests; I thought all of the '12 shootout lights got the IS testing, but as you note, not all did, and of course, the ones I looked at the second time, weren't!

Just speaking for myself - because riding around with something like this as a supplement to every emitter doesn't exactly look like a worthwhile tradeoff to me: Total 'out the front' lumens are dependent on several other things besides the extent the emmitter is driven to. An efficient optical system and an effective beam pattern can make a difference of a lot more than 30%.

Since most people in this forum seem intent on 'trading up' every few years anyway - its probably incidental. Personally I don't have any such intentions and already drive with as much or more lumens than anyone else on the board. My emitters are only driven to 80%. I probably just deal with less heat issues.