The M43 has a typical Carclo 10507 beam pattern, which is basically a big wide hotspot with almost no spill. There’s a faint glow around the hotspot, but it’s very dim. Almost all the light is in the hotspot, and it’s pretty wide so I describe it as a wall of light. During use, I find that the hotspot is so wide that the edges of the hotspot light up nearby objects and this near-field illumination can make it difficult to see things in the distance.
The D4S beam looks more like a traditional reflector. It has a small and bright hotspot, and around it is a much dimmer but still usable spill area. The brightness looks like a flat round plate with a can of soup stacked on top, right in the middle. It’s basically two levels, like a - shape.
The D18’s beam looks similar to the D4S, except it also has a corona around the hotspot. So more of the light falls in the spill area, which gives it a lower cd/lm value. The brightness looks like that same “plate with a soup can in the middle”, except the soup can is surrounded by a hill of mashed potatoes. I guess it’s more of a .-. shape. Or, another way to picture it is an upside-down cup on top of a small hill. Or, now that I think about it, it’s shaped like a boob in cold weather. The D18’s brightness chart looks like a boob.
Perhaps I can get a beam shot with all three, but the tints are all different so it’ll look weird. They also each have pretty large beams so I’ll have to put them fairly close to a wall in order to fit them all in one frame.
For now, I’ll just make a diagram to describe approximately how the light is distributed within the beams:
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