What criteria they use at ANSI to measure lumens.
I compare 1k lumens from the Chinese manufacturers
and 1k lumen from ANSI, and it seems much brighter.
Please, explain. Thank you.
Cheers.
ANSI does not determine what a lumen is. It is SI unit. ANSI does describe standard methods how to measure how much light comes out of light sources as opposed to the total lumens produced, the ANSI-lumen is therefore a different unit. See Difference Between ANSI Lumens and Lumens | Difference Between
Chinese lumens is another entirely different unit, many BLF-threads are devoted to it, just as the chinese mAh.
Light output of a flashlight can and vary often a lot as it is powered by a (depleting) battery with reducing voltage. The question is what exactly is the light output of a flashlight then? ANSI measures this output 30 seconds after the flashlight is switched on with freshly charged cells.
A similar practical issue is measuring runtime; how do you define runtime? ANSI states the runtime as the time interval between when the light is switched on with freshly charged cells, until light output is 10% of initial output.
So ANSI is also a standardisation for flashlights to deal with practical issues that are not present with projectors that are plugged in the wall.
Thank you both for your replies.
I have read the document, however,
reading and comprehending is a different story.
I will re read it.
I gather an ANSI lumen is more accurate
that casting lumens to the wind, like some do.
Thanks again for your guidance.
Cheers.