wrote
wrote in

Sorry, but the fellow who told me that is a life-long EE, and one of the
world's leading laser experts. While watts as used in connection with
incandescent lamps has always referred to consumption, the light output
can also apparently be measured in watts. I choose to believe my friend,
whom I've known and respected for 10 years, on this score.

Absolutely. Watts-out/watts-in gives efficiency directly. W/lumen
gives
a
relative number but not as useful.

But what does efficiency have to do with brightness? He may be
technically
correct, but how can a consumer tell what he is getting?

Visible energy out is the whole point of a light bulb, isn't it?

Say one bulb is 100 watts in, 65 watt out, it would be 65% efficient.

Ok...

Another bulb is 50 watts in, 49 watts out, it would be more efficient, but
not as bright.

Do you want a 49 watt out bulb or a 65 watt out bulb? If you only need 49W
of
illumination, certainly you would buy the smaller bulb.

The poster said the EE stated efficiency was the determining factor.
Therefore, he says the 49 watt output is what counts because it is more
efficient. He states that lumens is not useful. I say BS.

This guy may be a genius, but cannot explain his theory to us commoners. Or
a whole lot of fact was left out. I don't care how efficient a lamp is, if
it is not bright enough, I'm getting a bigger one. More watts = more light.