So my Blaze light has given up, and is fit for the bucket. Therefore, for the past few days, I have been investigating a replacement light, which I shall get for my birthday. And it arrived, courtesy of Amazon, today. It's a Moon XP500, with (you guessed it) 500 lumens.
Now, my current working light has 220 candlepower, and I thought it was reasonably bright. The new light arrived at work and I put it on (purely for testing purposes, clearly - my birthday is still many weeks away) in the kitchen to see how bright it was. Seemed fairly bright, but nothing spectacular.
However, this evening, I tried it out in the dark. And holy crap, I now understand the warnings about not running this thing on a street (or, even worse, on a cyclepath) pointed upwards in any way - this thing is ridiculously dazzling. I had it pointed right at the ground and stood some way away from it and yet it was still unbelievable.
My plan had been to run it on the lowest setting (120 lumens, I think), mainly because I figured that would be bright enough on the roads and it would mean that it would run all week without needing a re-charge. That's totally what I will be doing too, having seen how bright it is!
But in the context of this thread, it now explains to me what occasional cyclists have on their bikes that blinds us. Even with this thing pointed at my front wheel, it was still dazzling when on the full 500 setting! Therefore, I can only guess that some people assume that the light pointed down will mean it doesn't dazzle people, but the brief testing I did with this light shows that such lights can still be a menace if left on such a power, irrespective of where it is pointed.
(YMMV, of course, depending on your light and its cut-off settings. You'll see from Moon's web site that it has different "spot" and total angles, which I could tell when shining the light in the pitch dark; there is a definite brighter centre, with a much less aggressively lit wider area of light. Goodness only knows what it would be like if I was looking at it while standing in the "spot" angle...)