On Thu, 26 Nov 2009 08:35:59 -0800 (PST), Andy Dingley wrote:

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.

People don't need to understand it, only to get used to it - how many
actually understood what a 100W tungsten lamp was? Its "brightness"? Colour
temperature? Angle? They were simply used to them and knew automatically
that they could adjust the amount of lighting in a room by increasing or
decreasing the wattage and roughly what they needed. The bulbs of any
particular manufacturer were generally similar and therefore there was no
problem replacing like for like. Rating CFLs by there wattage equivalence
was a good idea, but badly implemented. If the ratings had shown
equivalences to tungsten lamps that most people would have agreed with, and
all manufacturers stuck to, then they'd have been useful. Instead they have
taught people to be wary of believing manufacturers claims and ended up
with a lot of people installing CFLs that give subjectively poor lighting
that they are dissatisfied with.

SteveW