in germany there is a big biking community, and they have the same problems like we orienteers. how to ride a 70kmh downhill in the winter after work ? the people who can't afford it to buy a lupine betty (900 euros) just built their lamps on their own. so why just build a headlamp for orienteering on my own? as we are geeks, that's THE way anyway ;)
so i just took an old helmet used on constructionsites, a standard 50mm 12V 20Watts Osram IRC Halogenspot (they have a special coat on the reflector which puts infrared light back into visible light - so they have a bigger light output), some cables, a switch, mount it with some parts of my little brothers metall construction kit to the strap sinside the helmets an put on a battery (LIION 14.4V - 6Ah) and a have really bright light for about 90 Euros (60 Euros for the battery) which is brighter than the standard Silva 10/20Watt thing.
btw. the lumenvalues from the manufacturers are more or less fantasyvalues. the guys from the biking community on the web (
http://www.mtb-news.de/forum/) took several lamps and measured their light output in an integrating sphere (ulbricht - sphere).
Results: SILVA 20W - something around 400 lumens (according to the skogsport, which is in comparison to my own lamp somehow realistic)
Osram 20 Watts IRC @14V 530lm, @16V (full battery) 776lm
Lupine Wilma 600lm
Lupine Betty 903lm
Lupine Edison HID 522lm
the petzl ultra wasn't tested, but i don't think that it has only 350 lm, i have seen them in sweden and they have been brighter than the standard ones.
but they have measured HID's up to an real output of 9100lm !!!
some pictures:
http://picasaweb.google.com/Ghostdriver85/Leuchtve...#
and 20W IRC vs. standard 10/20 watts, somehow too bright:
http://picasaweb.google.com/robert.kruegerol/Lampe...#