Originally Posted by
cyccommute
I'm pretty sure you have me on ignore but here goes anyway: I've tried to explain this to you several times. Lux is a valid measurement but so is lumen output. Lux is not valid if you don't have a distance measurement. My 650 lumen lights have a lux measurement of 1.3 million. What does that tell you about the light coverage. It also has a lux measurement of 29 lux. Which measurement do you want to use? For bonus points, how far way from the source is each measurement?
Just giving a lux number for a light tells you nothing about the light without the distance to the target. To put it in chemical terms, I have a reaction with compound A and compound B going to compound C. If compound A has a concentration of 4 moles per liter and compound B has a concentration of 2 moles per liter while compound C has a concentration of 6 moles per liter, how long has the reaction been going on and what was the starting concentration of A and B? You can't tell me because you don't have enough information. If I told you a rate constant, you could figure out the problem but without it you can't.
Same holds for a lux measurement. Without knowledge of the distance to the target, the measurement is meaningless. If I have the lumens, I can calculate a lux at any point from the source to infinity. I can't determine if the light is bright or not based on just the lux measurement. A 29 lux light could be a 1 lumen light measured millimeters from the source or a million lumen light measured 10 km from the source. I can't tell and neither can you.
I know the difference between Lux and Lumens. Most reputable light makers list Lux over the areas and distances described in the German regulations, which state that certain areas at certain degrees and distances from the headlamp mounted at the particular height and angle relative to the ground.
Therefore, I know that the light company has done the necessary measurements so that I know it works in a particular manner, hence I know that it's over a threshold performance.
As far as lumens goes, it's just a crapshot measurement that doesn't state when the light actually goes. In addition, it's grossly exaggerated by most makers, because the US doesn't have a mandatory testing service that must be undertaken before a light enters the market. So, when I see lumens, I know that 99% of the time there's no quality minimum that has been surpassed.
Yes, you're blocked as I find your comments distracting and really you want I'm totally bored.