SF L4 Rumors

[Art Vandelay]

I can understand why people are skeptical of the numbers that come from manufacturers. Many times these numbers seem inflated. Details about how they got the numbers are usually unavailable. I can see how some might "optimize" the results just because the competition does it.

Surefire is one of the few exceptions to this trend. They give real numbers. If anything, I'd say the numbers are on the conservative side. Surefire flashlights are usually brighter than flashlights from other companies that supposedly have higher lumen ratings.

I don't have an integrating sphere, etc. to check the lumens claims. Even if I did, I would only be checking one flashlight. With the luxon lottery, I could be above or below the website numbers. That would not prove the website numbers were too high or too low.

I'd say that 100 lumens is not the maximum, I'd say that the L-4 record high is more than that. Even the average L-4 is probably over 100 lumens. I wish they had used more precise language like average lumens or mean lumens.

 

[CM]

...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?
...

I presented a *possible* solution in my last post. They can present a "typical" which is what you refer to as a cluster. I'd personally prefer two numbers (hey, I'm a techno-nerd). A guaranteed (minimum) number such as the 60 lumens above, and a typical (ie average) number such as 100 lumens. Specifying an upper bound serves no purpose. I know presenting two numbers will never happen since marketing wants to keep it simple, and the competition will never do it and to do it just puts SF at a marketing disadvantage. But to keep things honest, they can guarantee an output level and a typical level. If they own their own IS, they can do statistical sampling of their product and periodically check the numbers. I suspect they do this (probably somewhat informally) as any reputable manufacturer has some statistical process controls in place. BTW, specifying a guaranteed performance and a typical performance is not an unusual practice. Check any manufacturer's data sheet. They will specify a minimum guaranteed performance number and a typical number. But like I said, probably won't happen. I'd love to see Surefire take the lead though, and maybe they can educate people about "the competition and specsmanship"

That's just my measly 0.02 worth.

 

[HarryN]

The L4 has been around for a while - I would not be at all surprised if the newer ones had better (higher brightness) Lux Vs in them then the old ones.

For my own work, I use the "50 %" rule to account for thermal and optical losses. I take the minimum of the lumen range from the bin code of the Lux Vs (WWOS in my case) and divide by 2.

W brightness = 147 - 192 Lumens
HarryN divide x 2 rule = 147/2 = approx 70 Lumens

I have had people tell me this is a bit conservative.

Interestingly, it comes out pretty close to the 80 Lumens measured by LSI for Lebkuecher, and is remarkably close to what I have seen from other attempts to measure the "real" output of Lux V flashlights at local flashlight meets and here on the forum after they have warmed up a bit.

It also seems close to what SF might be saying - if you happen to get a "top of the range W bin Lux V and divide by 2 ( 192 / 2) it gets real close to the "maximum" 100 Lumens.