However, 4Sevens advertises 189 out-the-front lumens. The MiNi probably drives the LED at closer to 1000mA, so the XP-G specs indicate 250% of the nominal luminous flux or 347.5 lumens at the emitter. This flashlight features a Cree XP-G LED with an R5 brightness bin that gives 139 lumens at 350mA. This number is even lower than "out the front" lumens.Īs an example of how lumens can vary, take the 4Sevens Quark MiNi 123.
Lumen scale full#
Depending on how well regulated the light is, the output can continue to vary with battery voltage.įL-1 lumens or ANSI lumens The ANSI/NEMA FL-1 standard requires an integrating sphere and uses a reading taken after the light has been on full power for 30-120 seconds. So the initial output can be fairly high and then drop by 10-20% within a few minutes. Instead the output usually drops off early as the LED heats up. However, a flashlight rarely has consistent output. This way different flashlights can be compared using consistent test procedures. CPF users MrGman and bigchelis have calibrated integrating spheres, test flashlights that people send to them, and publish their results in posts that are stickied in the CPF LED Flashlights forum. Out the front lumens To measure the actual light output of a flashlight, an integrating sphere (see Wikipedia article) is needed that captures all of the light and distributes the light equally so that it can be measured accurately regardless of whether the flashlight has a small hotspot or a wide flood. Even then, these numbers are always going to be higher than the actual light output by the flashlight.
![lumen scale lumen scale](https://i.pinimg.com/originals/37/f9/e9/37f9e913ab0a895ee993ff7c26fb9a87.png)
But actual output depends on the voltage and current delivered to the LED. Lumens are sometimes measured "at the emitter" or "out the front." Emitter lumens will always be higher than out the front lumens because there are some losses involved as the light bounces off the reflector and is filtered somewhat by the flashlight lens.Įmitter lumens LED manufacturers publish specifications listing the lumen output of their LEDs (see Brightness Bins) and sometimes flashlight manufacturers will just take the highest value for the LED in their flashlight and say that is the output. For scale, a 60-watt incandescent lightbulb produces 890 lumens, a 40-watt bulb is 460 lumens, and a pretty decent flashlight produces about 200 lumens. Lumens are a measure of the total light emitted by a LED or flashlight (see Wikipedia article for more information on lumens).