Let me be a bit opposing... I agree with that the actual lumens not (usually) corresponds to the perceived brightness.
According to my experience of several different lights I object against the square root thesis AS AN ALWAYS CURRENT RULE.
Sometimes I hardly perceive 5 times difference as twice. Other time with other light and brightness I perceive twice the brightness as twice.
When I compare the 45 and 150lm modes of my Fenix TK20 I always perceive 150lm mode as at least twice as bright as 45lm. With Quark 123/2AA I perceive the 170lm mode as at least twice as bright as 70lm mode.
And my lightmeter confirms the stated differences.
However, I think it's really a quite subjective issue what we perceive.
Regards, Patric
Yes, with 4 times the output, the range of the light will double and the light will appear twice as bright to the eye.
This is because the perceived light intensity is proportional to the square root of lumen output. So if you double the lumens, the light is only intensified by a factor of square root 2 or 1.41 times as bright. It should also throw 1.41 times further also, as long as you compare the same light with different outputs as the beam angle is very important here. A smaller beam angle will throw farther than a wide beam angle.
If you quadruble the lumens, the light is intensified by a factor of root 4 or twice as much.
I messed about one evening as I was tyring to come up with a formula that would enable me to work out approximate ranges of lights so long as I had the manufacturer specs for the throw at a particular lumen output:
Throw = Lumens x 1335
i recommend researching the Weber–Fechner law, and Stevens' power law with respect to visual perception.
Like if discussing comedy movies. Which is funniest? One person can think that Dumb dumbiest is twice as fun as The naked gun. Other person says it's three times funnier...
Regards, Patric
I was so impressed yesterday with an old incandacent mag 3 D light! I hadn't used one in years and my expectations were that it would only be a 1/5 as bright as my EDC 140 lumen light (as my EDC 140 lumen light claims to be 5X brighter!)
Rather than being only a 1/5 as bright (as surefire would say) I thougth wow! this thing throws farther and lights up a bigger area! My (unnamed) 140 lumen LED lights up a smaller area perhaps 5X as bright but that's not helpful for seeing better as much of that light bounces back and blinds me!
Anyone know - is that because my tints are too hot? Would I be able to see better with warmer tints?
actually, laural and hardy were much funnier then both your movies combined, so you need an sst.
Square root is for a point source, not a typical flashlight beam on a typical surface.Yes, with 4 times the output, the range of the light will double and the light will appear twice as bright to the eye.
This is because the perceived light intensity is proportional to the square root of lumen output. So if you double the lumens, the light is only intensified by a factor of square root 2 or 1.41 times as bright...
I am still doubtful about some of these statements. When I compare my TK30 with 2xCR123 I really perceive 370lm mode as more than twice as bright as 100lm mode. And I am quite sure other will think that too. Am I unnormal?...Stated another way, a 400 lumen light will visually only appear 1.58 times as bright as a 100 lumen light