On 26 Nov, 14:58, "John" wrote:
It is a pity we are 'stuck' with relating brightness to wattage. If we used
a proper definitive measure of brightness then manufacturers would have to
be more honest.

Why? Would anyone still understand it? Are such complex topics taught
in school science these days? Look at LED marketing, where they
cheerfully use the right words, but in any order that makes the snake-
oil sound best.

"Solid angle" is seemingly a concept that only lives in university-
level maths these days, so I don't know how they're going to teach the
difference between lumen and candela anyway.