My understanding is that SureFire gives its incandescent lights a lumen rating based on the fact that the output changes as the batteries drain. The rating is not the maximum or peak output but a more realistic rating of the output during use.
For LED lights where there is known variation in output from LED to LED giving a "maximum" rating would imply to me that SureFire were in some way limiting the output of the LEDs that were naturally capable of producing more than [lets say] 100 lumens.
SureFire are well known for their lumen ratings to be realistic and conservative but as people have noted it is a difficult balance to strike.
If you measure the lumen outputs of a reasonable number [100 or 1000?] of production samples and most [lets say 80%] cluster around about 100 lumens but there are some that are as low as 60 lumens and others that are as high as 140 lumens then what do you do?
Does it really matter that there will be a few that are either lower or higher than the 100 lumen rating? Especially since the general user has no real way to verify the actual lumen output of the flashlight they have.
But, do you keep with a lumen rating you know is inaccurate because on your splatter chart of tested outputs you do have a few that are that low?
How do you justify that to a Marketing department just itching to sing the praises of the products and concerned that joe-public doesn't have a clue about lumen ratings and all the detail, but sees another brand using a higher rating and buys that instead?
I believe that the term "maximum" should not be used by SureFire - certainly not for incandescent models, and it would be great to know whether this is marketing speaking or engineering advising marketing etc.
PK once said the output of a flashlight is what it is.
I say it is either enough light for the task or too much light. Knowing exactly what the output is does not change that so what is the real world point of knowing?
The output rating can help you decide which flashlight to buy if you already know the sort of beam you need for your application. The trouble is that the lumen rating does not tell you anything about the beam.
You can not trust the lumen ratings of any flashlight of any brand as tool for comparing flashlights and selecting from those the right one for application.
The only way to do that is by trying them out and comparing them side-by-side.
Getting all hung up on whether a lumen rating is accurate only matters if your intention is to know accurately what the lumen output is for your specific flashlight. This is not the purpose of a product rating (imho). Furthermore it is not an attribute that impacts on how well it performs in use.
To those of you who really care to know exactly what the lumen output of each of your flashlights is - I say - send them to a test lab accredited to perform such tests and get a test report. If you don't care enough to do that I say you shouldn't get so concerned about the accuracy of product lumen output ratings.
My humble opinion is that you should either care enough to actually find out or not care at all. I'm sure you'll be happier for it making the choice! I am.
Al
P.S.
If SureFire are to be held to account, will other manufacturers be treated in the same way?