Lumen rating consistency?

[Rusty Joe]

I have the Inova XO rated at 82 lumens and yet my Mag 3 D has as much brightness rated at only 58 lumens.

The Magcharger is supposed to be 233 lumens, and yet it outshines the ultrastinger at 295 lumens (it's my experience that Streamlight ALWAYS overshoots their lumen ratings!)

Other lights, like the Dorcy 120 lumens is barely 60 lumens, not near as bright as it is advertised with plenty of artifacts in the beam.

Surefire is pretty conservative in their measurements with their 65 lumens equaling almost 85 lumens.

My question is, how is there this much difference in the estimation of lumens? Is there a definite standard on how these figures are arrived at??

 

[Rusty Joe]

Looks like I posted this in the wrong place!oo:

 

[jdong]

You could go through and analyze the marketing tactics that arrive at these figures, but this explanation is the simpler yet equally accepted:

They pull the numbers out of a hat.

 

[Dr James Fox]

They do not use the same standard for measuring lumens and very often lumen ratings between different manufacturers are not comparable. Some methods to calculate lumens are:
The lumens of the bare bulb using the flashlight power supply.
The lumens of the bare bulb using a laboratory power supply.
The lumens coming out the end of the flashlight.
The predicted maximum lumens of the bulb that the maufacturer claims based solely on mathematices and not actual testing.
The estimated lumens of the bulb that they calculated out for the most optimal condition of the power supply in their flashlight.

From: http://www.flashlightreviews.com/features/output_vs_throw.htm

 

[Gunner12]

Some companies state the highest number on the spec sheet.

Some calculate LED lumen at the drive current from the sec sheet.

A few actually test the output to verify.

Remember that a 20 lumen throw light can out throw a 100 lumen flood light.

Lumen measures overall output.

 

[KeyGrip]

Don't get caught up in output ratings, be they lumens or lux. It is difficult to make a meaningful comparison between two lights unless you know how they're measured, and as it was explained above, there are a lot of ways to measure.

 

[xcel730]

I'm not an expert in this field, so take what I say with a grain of salt ...

The problem is there isn't really a standard to how they come up with the figures. Most of them take what the LED manufacturer claims the maximum lumen the particular model LED is able to produce. This is under the ideal conditions, the LED driven at the maximum voltage. A good portion of the lights get dissipated inside the lens. Plus the battery type and driver plays a factor as well.

Very few companies would use the actual lumens that come out the front of the lens. It makes sense too since most non-flashaholics will take flashlight A with 150 emitter lumens over flashlight B with out-the-front 80 lumens. Flashlight B could easily be brighter than Flashlight A, but doesn't 150 lumens sound better?

 

[yekim]

What we need is an SAE for the flashlight industry.

 

[Marduke]

Don't confuse throw with total output. That plain old Mag will appear much brighter than smaller, brighter flashlights which are mostly flood because of the beam pattern.

 

[curlyfry562]

This is why I always buy surefire anymore, that way I don't have to worry about these things, so at the end of the year when I buy the Invictus, I know it will kick a#%

 

[Illum]

almost in another way, Surefire itself is inconsistent in its own lumen ratings...and off at times by several hundred lumens. Good thing though, Surefire is the complete opposite of [almost] all other light manufacturers. It underestimate rather than overestimate

a few examples
Surefire A2: spec'd at 50 lumens, the tested output ~79 lumens
Surefire M6 LA MN21: spec'd at 500 lumens have been reported to be actually 1000 lumens
MN20: spec'd at 250 lumens actually performs as a 500 lumen lamp with fresh cells
MN15: spec'd at 125 lumens [when driven in the M6 exceeds 200 lumens by js's standards]
etc.

 

[xcel730]

I can't imagine what 400 SF lumens will look like. I'm tempted to get the optimus and settle with 200 SF lumens

This is why I always buy surefire anymore, that way I don't have to worry about these things, so at the end of the year when I buy the Invictus, I know it will kick a#%

 

[Ninjaz7]

You could go through and analyze the marketing tactics that arrive at these figures, but this explanation is the simpler yet equally accepted:

They pull the numbers out of a hat.

+1 on the bullwinkle theory...you caught me off guard,I was expecting a technical thesis...Cheaper manufactors have to exploit this part of marketing,every ninth person falls for it.

 

[Wattnot]

I like analogies. Sometimes too much. But when it comes to Lumen ratings, if you are familiar with horsepower ratings and cars, you'll understand this:

Surefire Lumens are measured at the wheels where everyone else's are measured at the flywheel.

How'd I do?

 

[LukeA]

I like analogies. Sometimes too much. But when it comes to Lumen ratings, if you are familiar with horsepower ratings and cars, you'll understand this:

Surefire Lumens are measured at the wheels where everyone else's are measured at the flywheel.

How'd I do?

Pelican, Novatac, and some others measure minimum torch lumens as well as Surefire.

 

[2xTrinity]

I like analogies. Sometimes too much. But when it comes to Lumen ratings, if you are familiar with horsepower ratings and cars, you'll understand this:

Surefire Lumens are measured at the wheels where everyone else's are measured at the flywheel.

How'd I do?

Nice analogy.

Also, in the car industry, horsepower at the flywheel is almost univerally reported simply because it's the "biggest" number they can legally advertize. With flashlights there is no standard measuring system.

The following are a few methodologies I've seen, in order from most inflated to least inflated, and including examples of who uses it

• Arbitrary Large Number -- 100% BS. Lots of eBay sellers. Just about all "X-Million Candlepower" spotlights.
• Largest Number on LED Manufacturer Data Sheets -- Lots of eBay sellers. DX/Kaidomain, other Chinese Vendors.
• Table lookup on gross LED lumens using measured current -- Probably the most common among most flashlight companies who actually post lumens, ie Fenix.
• Table lookup with "correction factor" to estimate optical losses -- Many CPF Vendors who don't have optical testing equipment. This should produce fairly accurate results, actually.
• Actual Measurement, best or typical case
• Actual Measurement, worst case -- Surefire. If the user were to be obsessive enough to test one in an integrating sphere and discover their was too low, SF would be obligated to replace it under warranty/