Originally Posted by JohnJ80

The range and availability of battery lights that give great output is huge. So is the relative magnitude sale of battery lights to dynamos. Those two facts alone put to rest the idea that battery lights don't "just work" and that they are not reliable nor difficult to use. As well, the market seems to say that they are pretty easy to use or the sales volumes would not be what they are. And there is not a 6-10W loss of power (not at all insignificant), there is no need for custom built wheel and hub (which is heavier rotating weight) etc...

I would expect that dynamos are reliable but I would not expect them to be any more reliable than a simple battery (I'd put the actual light assembly as a wash). I would also point out they are full of single points of failure as a mechanism both the dynamo it's self and various parts in the dynamo. A battery light can cover the single point of failure issue by carrying an extra battery. One cannot carry an extra dynamo hubbed wheel.

So, it remains that other than fascination with the gadget, I don't see the benefit of a dynamo in the predominance of bike lighting applications except where there is no ability to charge a battery.

FWIW, having taken countless beamshots myself, and being an amateur photographer, I well understand that I can make pretty much any beamshot look how I want it to look by fiddling with the exposure. But, even presuming those are the exactly representative beamshots, it's pretty simple to get a decent light with a great beam these days in the battery camp - and you'd have more choices than you'd probably want to look at.

J.