In article , HeyBub wrote:
Frank wrote:

Might be a great light, but it is built for a bicycle, gives no idea
about light output, and is pricey for your needs.

It SAYS, under "Specs"

1 LED
110 Lumens

My take is that 110 lumens is produced by the LED (maybe
optimistically) if given "full power" according to nominal design of the
system or a "characterizing current" of the LED (or worse still is maximum
available from the LED) when the LED is cooled to having either its
heatsinkable surface or the hottest part of its semiconductor chip at 25
degrees C (77 degrees F).

(Thankfully, the Seoul Semiconductor LED that I consider most likely to
put in a bicycle headlight has its "upper grade" version supposedly
producing minimum of 100 lumens at 350 milliamps IIRC - very good
actually.)

Lumens produced by the LED do not all make it out of the lighting unit.
Reflectors are not perfectively reflective, and absorb some of the light.
Lenses reflect some of the light backwards, and the light reflected
backwards by a lens is usually mostly either absorbed or ending up going
somewhere other than where you want the light.

Maybe this bicycle light, shone upwards at a ceiling painted with
brightest white paint, will illuminate a room as well as a 110 lumen
lightbulb (typical of many 15 watt 120V ones) does. But I would not count
on that, not even from a $129 bicycle headlight - even though it would
kick kiesters and tookuses as far as bicicle headlights go if 75 lumens
usually came out from it.

- Don Klipstein )