In article ,
robgraham writes:
On 1 Oct, 10:11, (Andrew Gabriel) wrote:
In article ,
* * * * "Mungo \"Two Sheds\" Toadfoot" writes:

Are they A Good Thing for cheering up a kitchen through the winter, and

Definitely not. They have the most appalling effect on the colour
of food, and unless you lined the ceiling with loads of tubes to
get the lighting level up to that of midday sun, the colour will
look wrong.

possibly having a beneficial effect on the symptoms of SAD? I'm having some
bother finding a 6' one locally but if they're worth having I'll continue
the search.

SAD needs a bright light. There's no evidence colour makes a scrap
of difference, but the manufacturers of special lights like you to
think it does so you'll buy their very expensive replacement tubes.

You need to tell Screwfix that as their spectral diagram in the Lamps
section shows SAD application as being beyond Daylight (16000k).
Snakeoil perhaps!!

Yes.

As I said in another thread, daylight is actually quite complex.
Although it measures 5400K, because the red and blue components
are split up in the atmosphere (red mainly coming direct from the
sun, and blue scattered and coming from all over the sky), a few
clouds can radically change it. A cloud blocking direct sunlight
can push the colour temperature very high (probably close to
your 16000k). When you look at objects illuminated by daylight,
you'll see a very different colour temperature depending if the
object is in direct sunlight (with red components) or in shadow
(so only blue components). For anything other than a horizontal
surface under a clear sky, an object illuminated by sunlight will
never actually see the 5400K -- it will either be higher or lower
depending on precise circumstances.

I have a 20,000K metal halide lamp. It's fun for lighting up the
garden at night at Christmas if it's covered in snow, but quite
useless for anything else (except possibly lighting corals and
tropical fish which is what it's designed for). However, you
can't run it indoors for longer than a few minutes, as although
it has an outer glass bulb and an explosion-proof luminare (as
required by all MH lamps), it still generates too much ozone
(too much UV leaks through the outer glass bulb, although not
out of the luminare). Incidently, This colour temperature,
lacking severely in reds, makes people's skintone look very
sick ;-)

--
Andrew Gabriel
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