krystar78: standardized lumen measurement is done by measuring amount of light output using sophisticated detection hardware.
the source of most high power flashlights nowadays are all LED’s made by the same manufacturer Cree. that doesn’t mean someone can’t copy CREE’s chip and make it dirt cheap. alot of Chinese manufacturers knockoff CREE’s designs or even label theirs CREE when they’re not. and those unreputable vendors will also label their light 2000lumens when they’re not.
batt_man: Lumens is a rating of light in a dark room. Lumens are a rating that is good for light bulbs but bad for flashlights. Lux is much better for flashlights.
Lumens is a 360 degree rating, not really what you want in a flashlight. The lux rating takes direction and beam angle into account. So say you have a flashlight rated at 2000 lumens. It might up a room real well because the beam is not focused properly. A flashlight with 2000 lux will be a much better flashlight for lighting the spot its being pointed at.
dogbuns69: Chances are they dont output 2000 lumens. It’s just grossly exaggerated. I wouldn’t trust the ratings of those no name brand lights.
There’s three ways to report total light output for flashlights.
There’s emitter lumens which meaures light emitted straight from the light source. This gives you the highest number.
There’s OTF or out the front. This is measured after the reflector/lens. There are some losses through each interface but it is a more realistic number.
Then there’s ANSI lumens. The key thing is that you measure output after being powered on for at least 30 seconds to reach a steady operating state. This gives you the lowest number, but is the best way to determine real world light output.
Most reputable flashlight companies report OTF or ANSI lumens and they will typically specify it.
The most accurate way to measure lumens is in an integrating sphere.