In reply to ianstevens:
> I'm simply stating what the graph on the product page on Fenix website says. The 1000 lumens is both LEDs combined I think, and an any case, lumens don't work in an A+B kind of way.
> But as you say, somewhat academic. But as an academic I like to consider these things
I'm trying to get involved in fewer pointless arguments on here lately, but since you take academic pride in being correct you might want to double check both of those facts above.
Is this the product page in question?
https://www.fenixlighting.com/products/fenix-hm65-rechargeable-headlamp
The graph is labelled "Spotlight Runtime Chart". The spotlight being a maximum of 1000 lumens, and the floodlight a further 400. To get to that chart you have to scroll down past the 'Specification' bit, the first line of which reads: "Max Lumens: 1400"
Also I believe luminous flux, in lumens, is a scalar quantity which does indeed add up like that.
(Luminous intensity, in candela, would not since that depends on the beam shape.)
Is this your field of expertise, academically speaking?
Post edited at 19:13