Has this been settled yet.? I think Firefly mode is less than 1 Lumen. Not sure on the Moonlight mode though. Anyone know the definitive answer.?? Thanks
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what makes you ask?
to me, moonlight is less than 1 lumen, to a single decimal place, so, 0.1 to 0.9 lumens,
but I have seen some lights claiming to have moonlight modes ranging from 1-10 lumens… Ive never seen a definitive answer.
to me, firefly is less than 0.1 lumens… iow 0.01 to 0.09
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What jon_slider said. Usually a “moon” mode is about 0.1 to 1.0 lm. Usually a “firefly” mode is about 0.001 to 0.1 lm. But that’s just a rough guideline.
A “moon” mode is roughly as bright as a full moon… meaning it illuminates surfaces to about 0.25 lux. This usually works out to about 0.1 to 1.0 lm, but it really depends on the light. Maybe 0.05 to 0.5 lm is a better estimate.
A “firefly” mode is more like the brightness of an actual firefly floating around at night. It’s bright enough to see the light itself, like to find the torch in a very dark room, but not really bright enough to shine it at other things. This usually is anything under 0.1 lm or so, though I find 0.01 or 0.02 lm is typically about right.
The numbers are all very approximate.
Both terms are also frequently used to refer to the lowest level a light can make, regardless of the actual lumen value. I find this a little annoying, because some companies say they have a firefly mode but it’s actually like 10 lumens and is about 500X too bright to count as “firefly”, but … sigh.
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I particularly enjoy that this is your first post in 11 years, like you’ve been away while waiting for the argument to be resolved 
The previous answers have pretty much nailed it, I always just look at the rated output in lumens rather than reading the marketing speil.
Welcome back to BLF
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I spend about 200 nights a year in hotels. I like a light that can be set low enough to allow me to find the bathroom without disturbing my sleep cycle. Some light advertising moonlight are too bright!
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Anduril lights such as the Wurkkos TS10 can reach extremely low outputs, as low as 0.01 lumens. I recommend the TS10 as a nightstand light, for its firefly output, as well as its Aux LEDs, which make the light easy to see in the dark. It is also very inexpensive.
If you like the option to use AA batteries, the new Emisar D3AA can do everything the TS10 does, even better. The new D3AA is more efficient, uses NoPWM, and offers a very extensive selection of LEDs to choose from.
If you like an Anduril light with both White and Red LEDs, the Emisar D2 is a fantastic dual channel option imo. Red light does not deplete the sleep hormone Melatonin. Using red light insures being able to get back to sleep more easily.
If you feel Anduril is too complicated for you, consider a Skilhunt M150, available with a nice warm 3000K 519a. its lowest mode is a moonlight of 0.2 lumens. It lacks the Aux lights included in the Anduril options, and the range of outputs is more limited.
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