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Old January 29, 2013, 11:30 AM   #10
mikikanazawa
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Join Date: September 26, 2004
Posts: 449
It doesn't really matter because the light manufacturers don't use the same method of measuring output whether it be candelas or lumens.

For example, most of the LED-based flashlights that use the same LED will have different output ratings. Some just use the lumen output spec provided on the LED manufacturer's spec sheet. And some will take into account optical losses (from the reflector, lens, window, etc.) and electrical losses (diminishing battery power). So it is possible to have a flashlight with a 100 lumen rating and another flashlight with a 500 lumen rating, and still have greater visible output from the 100 lumen flashlight.

The eye isn't equally sensitive to light at all wavelengths, so it is possible to have a flashlight with an extremely high lumen rating yet still difficult to see with. In a case like that, the output may be biased to to IR or UV portion of the spectrum, or it may be extremely narrowband, with a white appearance, but most of the emission in the blue or green area of the spectrum.

Sunlight appears white to us because the sun has a very broad (high bandwidth) spectral output. LEDs appear power efficient because their spectral output is more selective with lower average bandwidth.

So to answer the question -- just get a flashlight you'd enjoy owning!
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