![]() I'm comfortable riding 8-10 mph at 50 lumens, 14-15 mph at 100, and 18-20 at 200 lumens. My Dinotte headlight has 50, 100 and 200 lumen settings with the same beam. You can gang a bunch of low intensity lights together (like lots of LEDs are doing now) and add the lumens to get the 'same' output but it's not going to have the same distance and intensity as a single source of the same output. I can't do the optics (it's been a long time since physics) nor can I back it up but I can tell you from experience that 2 weak sources don't equal a single strong one. The amount of light hitting the target is going to be some fraction of a single 400 lumen source. If you take 200 lumen sources and shine them at the same thing you'll have two weak sources, each diverging as the inverse square of the distance. ![]() A stronger source is going to diverge less for a longer distance than a weaker source. ![]() Light coming from the focal point is going to diverge as it travels away from the source. When you make the light, the source sits at the focal point of the mirror system. If I could test them all in a lab, I'd still try to eliminate all those variables.I think we have to look at this as an optic problem. Hey, I appreciate the effort my original questions were about lumens, not optics, unequal distances, etc. Adding them together from multiple sources is probably correct for specific distances but once the distance changes.which happens all the time while moving.multiple sources aren't going to perform the same way as a single high intensity source. You can think of it as a single high intensity source will hold together longer than multiple low intensity sources.įrom the standpoint of how much light we perceive, lumens is a pretty good measure of light. The more individual sources you use the more the light is subjected to these factors. The light is traveling through air which scatters and diffracts it and absorbs little bits of it. There are going to be other factors involved too. The light from the array is going to be much, much dimmer. Move the target and the amount of light still drops by the square of the distance but you only have one source of light rather than 200. The distance to the target is the same but the intensity of the light hitting the target is much greater because the light travels the same distance from a single source. Now take a source of light that puts out 200 lumen. Since intensity follow an inverse square, the distance from the target is going to have a significant effect on the amount of light reaching the target. The intensity of the light on the target is going to be a certain value for a lamp at the middle of the array and different for a lamp a the outside of the array (assuming a flat target). The distance from the target is going to vary for lamp to lamp. But each lamp is going to be a different distance from the center of the light beam array where the light is generated. Turn them on and shine them on a target a given distance away and you'll have 200 lumens (the intensity of the light that we perceive). Let's start with 200 lamps of 1 lumen each with a suitable reflector for focusing them. Let's eliminate the variable of where they're aimed, then.I've been trying to come up with a way of explaining this and keep coming up short But, with a lot of hand waving and seat of my pants science, I'm going to try again. I'd rather have a weak source and good optics than a good source and poor optics. There's no simple answer to the question "does doubling the lumens double the distance" since it's so dependant on beam pattern. Concentrating the beam reduces how much area these lumens get spread over as the distance increases. This example is one where there are no optics, there is no beam pattern. And that's why beam pattern is important. The same 100 lumens makes for 7.9 lumens per square foot.ĭoubling the distance from 1 foot to 2 feet makes your lumens per square foot go from 31.8 to 7.9. So 100 lumens gets spread out over 3.14 square feet. The surface of the sphere is 3.14 (pi) times the diameter squared. Let's say that sphere is 1 foot in diameter and the lightbulb puts out 100 lumens. If you have a bare lightbulb then it spreads its lumens out in a sphere. Twice as many lumens doesn't help you see twice as far, though, right? Or does that get into a logarithmic-type scale, too?Depends on the optics.
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