I have been reading posts stating that our 140 lights exhibit very little visual difference between the 140lm burst and the 100lm sustained levels. Although our brains are not wired to perceive light in a linear manner, I have come to the conclusion that 140lm is an appreciable increase in output over 100lm.....under the right conditions. It is true that when one shines a Clicky on a wall and jumps from burst to high, then the 40% increase in output IS NOT perceived as such. But try doing this to prove my point.
Go into as long and as dark a room as you can find with a light colored ceiling, aim your light at the ceiling at one end of the room and keep your focus on the other end. Go from high to burst repetitively, and notice how much more the room is illuminated on burst. Note that both levels are coming out of the same light and that they are bouncing off the same point in the room. This ceiling bounce test is the next best test to compare luminous output levels, without resorting to an integrating sphere. The actual lumen value is not important. How the room is illuminated by different outputs.....IS!
Consider the mathematical difference between 100lm and 140lm. If our brains were wired linearly, then the 40lm increase would perceptually translate into another 40% throw and 40% spill. It is not. But Henry has posted and science has proven, that a 40% increase in output on paper translates to a 19% increase in the perception of throw and spill. That means that if a 100lm output can be seen 100ft. from the light, then a 140lm output can be seen 119ft. from the light. I am going to see for myself, if I can find a dark area in my heavily lit NYC neigborhood. Here is an excerpt from Henry's FAQ. page....."In general, you need to increase the light output by 40% for most people to easily recognize the increase in light output. That is, you would need to go from 85 lumens to 120 lumens in order to easily notice the difference. This translates into a 19% increase in beam throw."
My plan, although not 100% scientific, is to find a distance that I can measure using my footsteps, a distance at which point I can just barely see the light at 100lm. Then I will go to burst mode and take steps backwards until I can just barely see it. The added steps compared to the distance at 100lm will tell me how much farther a 140lm output can be seen compared to a 100lm output.
I welcome anybody else to do this, since this is an idea that I may not be able to impliment in my neigborhood. If any of you have a laser measuring device, your job would be easier. Try to find a terrain where it is as dark as possible, so that ambient light will not mask your dark adapted eyes, and the results.
Jeff
Keep in mind that even Seoul P4s will improve over time, at the very minimum, in the category of efficiency. My modded U60 uses the first generation Seoul P4. Seoul now has a U2 version of the P4, which gives more light for the same unit of power as the original P4.
