"Scott" wrote in message
...
On Wed, 9 Jun 2021 12:20:16 +0100, nightjar wrote:
On 09/06/2021 09:39, ss wrote:
..."Sales of halogen lightbulbs are to be banned in the UK from
September, with fluorescent lights to follow, under government climate
change plans"....
Apart from a few, rarely used, lamps that have yet to be changed, I have
long converted everything to LED.
Me too, except for my bedside lamp which is halogen for colour
rendition. Any comments on reading under a 230V LED spotlight? Would
you go for cool, daylight or warm?
We tend to use Philips Hue for bedside lamps, and these can be set to
anything from cool shady daylight (probably about 10000 K) to very warm
tungsten (about 2000 K). I find that a sunlight temperature (about 4000-5000
K) is a good compromise. Supposedly warmer light than that is better for
reading in an evening, so as not to stimulate the body to produce melatonin
which can cause problems getting to sleep because the body sees it as
daylight rather than "time to feel sleepy".
In the kitchen and in my study, we use MiniSun GU10s which are about 6000K -
just slightly cooler than LED bulbs which are sold as "daylight".
I've not encountered any LED bulbs which have bad colour rendition, though I
bet if you looked at the spectrum of an LED bulb (whether warm, daylight or
cool) you'd find various absorption lines and emission lines, whereas
tungsten is a more continuous spectrum. Certain shades of red tend to be the
ones than look darker than they should under LED, by comparison with natural
sunlight.
I took a series of photos of a standard coloured test picture under a
variety of lights (fluorescent tube, daylight CFL bulb, tungsten,
warm/day/cool LED, sunlight, shady outdoors) with my camera white-balanced
from a sheet of white paper under each light. The results were pretty
similar, apart from a pillar-box red which came out a bit dark under LED and
much darker under fluorescent.
https://i.postimg.cc/RCnFcqfM/daylight.jpg
https://i.postimg.cc/brbw8F8G/daylight-CFL.jpg
https://i.postimg.cc/W3d4Y1Hw/Led.jpg
https://i.postimg.cc/76jZFyv8/white-fluor.jpg
I'm not sure whether "daylight" (the first) was sunlight or shade, or what
colour the LED was - probably daylight coloured. The "white-fluor" is strip
light, and I presume it was cooler and not warm-white.
Note the different rendition of the red panel on the box of screws to the
left of the face.