ANSI-NEMA FL-1: Difference between revisions

Total lumens of output, measured in an integrating sphere after the light has been on for 3 minutes (actually may be 30-120 seconds like some of the readings below). This gives time for the LED to get hot and the battery voltage to sag which will usually decrease the output.

The amount of continuous runtime (in minutes) for the light output to drop to 10% of its original value (measured 30 seconds after turning the light on). This test is done in an integrating sphere just like the lumen test with light output measured every 15 minutes. In the past, some testers used 50% to be a little more practical, but with most batteries, the drop-off is usually pretty quick and the time between 50% and 10% usually is not long.

Light intensity in candela at the brightest part of the beam. A lux reading in the brightest portion of the beam is taken at some distance with the light on its brightest mode and tightest focus at some point between 30 and 120 seconds of turning the light on. The lux reading is multiplied by the square of the distance in meters to get candela. Regardless of the distance at which the reading is taken, you should end up with the same value in candela, therefore the measurement is independent of distance. A lux reading taken at 1 meter distance is the same as candela (since 1 squared is 1).