Originally Posted by
pierce
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).
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!