"Andy Burns" wrote in message
...
Arfa Daily wrote:

I have no trouble at all reading under
daylight, tungsten light of any description, or even linear flourescent
light. Just under those bloody things. I would be interested to hear if
anyone else finds the same thing.

Ignoring the fact that CFLs are acceptable to some of us, but not to
others, most of the anti-CFL brigade seem to say they have no truck with
linear fluorescent, what are the differences between "normal" fluorescents
and CFLs?

I'd expect the phosphors to be similar giving them distinct spectrum lines
(which I can *see* them when I notice a CFL reflected at an obtuse angle
against the AR coating of my specs), the CFL will be driven in the
kilohertz range rather than at mains frequency, and the linear fluorescent
will obviously be a diffuse strip rather than a diffuse point source ...
but how do these differences account for such a huge difference in how
people perceive CFLs ...


It's a mystery to me as well. I have a number of linear flourescents around
the house and in my workshop that I work in all day. The kitchen and utility
room both have them. The tubes that are fitted are a mish-mash of colours
including "white", "warm white" and "daylight". I have absolutely no truck
with the colour or quality of light from any of them. I could not, in all
honesty, describe the light from any of them as being 'sick' or having a
tendency towards green. I don't believe that the drive frequency has
anything at all to do with spectrum either, as modern linear ballasts are
also actually high frequency driver circuits. So it has to be a phosphor
thing I think. It is my feeling that linear flourescent colours don't look
'right' in a small bulb structure, so instead of using phosphors of those
colours, the manufacturers use tricolour mixes to try to emulate the colour
of tungsten lighting. Unfortunately, these phosphors don't produce the same
spectrum.

But here's a thought that just came to me. About 15 years ago, we owned a
children's day nursery, which we ran in a Victorian school that we bought.
Your typical infant or junior school that the older ones of us all went to.
The ceilings were very high, and each room had about 12 light fittings that
were very long pendants. In such large rooms, to get enough light in the
winter, it was necessary to use 100 watt bulbs. This had the dual downside
of of being expensive to run at 1200 watts for 10 hours a day in each room,
and the heat of 100 watt bulbs burning for that length of time every day,
had a tendency to burn out the light fittings every few months. So we
started fitting some CFLs that were called 'Dulux EL Globes'. These things
were the size of a large orange perhaps, and white. I can't remember what
the power rating of them was, but they easily achieved the same overall
light level in the room, as the tungsten lamps had. They started pretty much
instantly as I recall, but still took a while to achieve full running
brightness. But here's the thing. Although it cost us a lot of money to
equip all the rooms with them in the first place - I seem to recall that
they were about a tenner apiece - I only remember having to replace a couple
for failing over the years that we were still there afterward. And the
colour of the light was excellent. I wonder whatever happened to that brand
and type. Anyone else remember them ?

Arfa