Wenn es aber zu hell ist (auch, wenn es schön grün ist) gibt es keine Dunkeladaption des Auges und damit auch keine Empfindlichkeitserhöhung des Auges
Das ist einfach nur ein netter Rechentrick ohne Berücksichtigung der äußeren Bedingungen.
Ich denke auch, daß die äußeren Bedingungen in der Praxis das Problem sein dürften.
Was die "Rechentricks" angeht - dieser Sportsfreund scheint irgendwie Ahnung zu haben und hat noch ein zusätzliches Wirkungsgradproblem entdeckt. Er siedelt die Lampe bei nur 126 Lumen an:
"Userman:
I was an engineer for one of the lighting companies noted above for several years and I have to say something. I did a TON of research into this stuff, for obvious reasons, and even built up some version of this lamp. The one thing absolutely every hobbyist and even the overwhelming majority of companies neglect is the temperature rating of the LEDs.
Yeah, that thing is rated at 500 lm on paper, but that only is true when the gap junction temperature (the temp of the place where the tiny wire connects to the led face) is at 15 deg C. The moment you turn those leds on that junction is about 45 deg C. Your thermal path here is (1) LED > (2) Junction wire > (3) Luxeon Star module board > (4) thermal grease > (5) anodize layer > (6) aluminum heatsink > (7) Air at ambient, say 15 deg (it's night out andyou're wearing a jacket). When I mocked up 4W of power into a decent sized heatsink it hit steady state around 40-50 deg C, warm/hot. Lumileds expects at minumu an amazing heatsink made by a thermal engineer will have a thermal resistance from juncitno to ambient of 30 degC per watt. With only a single 1W led I'd expect your LED's are experiencing around 70-80 deg C at the junction.
Now for those still paying attention go check the light output of those LEDs when the temp goes up. Light output at 80 C for white & cyan LEDs is 80% of the 15 deg C rating (40% for red/ambers!). With 4 leds it gets worse and if you opt for the 5W luxeons, which are overall brighter, the problem gets even further exacerbated.
I'm rerating this headlamp at about 45 lumens (max) *4 * 70% efficiency (generous) = 126 lumens. Where the heck did 500+ lm come from? People, please do your homework before you start spouting numbers off.
Otherwise... looks well put together and I'm glad you like it, but it falls just a mote short (and only a little, this is really close) on your LED physics and your light reception physiology."
