Ted Edwards wrote:

For many years I've used a carbide lamp with a somewhat oversized
reflector. 4 hours operation on a film can of carbide. Good flood at
your feet with a real reach to the spot. I've been experimenting for
years with everything from candle lanterns to an inverter operated
flourescent I built in 1960. Until the LED lights came along there just
wasn't any serious competition to the carbide lamp.

That depends on your criteria and application. I used to use a carbide
lamp for caving. In terms of the duration-to-weight ratio, it was hard
to beat, and it was the hands-down winner for coolness factor. But a
6-volt halogen lamp put it to shame in terms of light output, as well
as maintenance and ease of operation. I haven't done any caving in a
while and haven't gotten around to trying out an LED lamp yet.

Bert