[quote=flashburn]
Whether it’s a good idea, it depends on your goals.
Here is an old thread summarizing the options:
Don’t just look at the first post, look also at the discussion.
Basically you’re sacrificing flood beam shape for more efficient throw. So if you want a pure or almost pure thrower - OK. If you want a flooder or a versatile light, it’s not so good.
A better way to improve efficiency is to use a single stronger lens….but there are tradeoffs to that as well because a stronger lens means narrower flood. You can in turn widen the flood beam by putting the lens closer to the emitter (there are limits to that) or using more emitters.
BTW, heating the bezel doesn’t mean much. Light loss is significant inefficiency (though not worse than reflector lights which lose a lot of light to spill) but the heating effect that it causes is negligible because:
First, LEDs at high power tend to produce much more heat than light.
Second, a major part (often most) but nevertheless only a part of it hits the head.
Third, the zooming part of the head is in most cases largely separate thermally from the rest of the light, so by heating it up you hardly affect anything else.