Light bulbs

[JohnW2]

do you know anything better?

There probably is no better general measure of light output than lumens, although it's obviously lux (which requires knowledge of the distribution of the light and distance from surface) which actually matters in terms of illumination of surfaces. I was merely responding to "the lumens should be on the packaging of the CFL" and cautioning that it did not tell the whole story (any more than watts did for incandescents) - a bit like saying "the cylinder capacity of the car's engine should be in the specification" and implying that it told the whole story about 'performance'.

I'm sure that Astra99 is right in saying that the day will probably come when everyone thinks in terms of lumens, and no-one will even remember what an 'incandescent lamp watt) is/was!

Kind Regards, John

 

[JohnD]

it's obviously lux (which requires knowledge of the distribution of the light and distance from surface) which actually matters in terms of illumination of surfaces.

Those factors appear to me to be irrelevant to the lightbulb on the supermarket shelf.

 

[JohnW2]

it's obviously lux (which requires knowledge of the distribution of the light and distance from surface) which actually matters in terms of illumination of surfaces.

Those factors appear to me to be irrelevant to the lightbulb on the supermarket shelf.

For 'general service' lamps/bulbs (something approaching 360° light distribution), they obviously are irrelevant (whether one thinks in lumens or 'incandescent watts'). At the other extreme, for 'spotlight', they are extremely relevant, and they have some relevance for lamps in between those two extremes.

Kind Regards, John