Discussion:
Local newspaper article on CFL and LED lamps
(too old to reply)
m***@att.net
2014-03-24 04:51:16 UTC
Permalink
Raw Message
The Kansas City Star ran an article today (23 March) about CFL and LED
lamps. It starts out with some good points about lumens and color
temperature, and how CFLs compare to LED. It also mentions the
incadescent phase-out. At the end it sort of devolves into halogen and
mercury FUD. I thought it was an interesting example of "retail"
lighting advice.

Link to the article:
http://www.kansascity.com/2014/03/21/4898642/the-light-bulb-test-how-best-to.html
This should work for anyone, but may only be available for the next
couple of weeks or so.

Matt Roberds
Ingo Thies
2014-03-25 21:28:49 UTC
Permalink
Raw Message
Post by m***@att.net
The Kansas City Star ran an article today (23 March) about CFL and LED
lamps. It starts out with some good points about lumens and color
temperature, and how CFLs compare to LED. It also mentions the
Thanks for the link. However, I am wondering why apparently everyone is
using the Kelvin scale "upside down", i.e. keeps labelling light with
high colour temperature as "cooler", without any further explanation of
this paradox. But when dimming an incandescent/halogen lamp it is
obvious that dim red (low current through the filament) is cooler than
bright white (full current), as well as noon sunlight (CCT about 5500 K
in summer at sea-level) ist hotter than the reddish light during sunset
(you can actually feel the difference!).

The artist's rule "blue=cold" and "yellow/red=warm" may apply to
surface/pigment colours or subjects of paintings (e.g. water vs. fire),
but not easily for illumination. Furthermore, the "warmth" of
illumination may also depend on the color-rendering index: The lower the
CRI the "colder" everything may look, especially if skin color is
rendered unnaturally pale.

BTW, technically, both CFL and LED (irrespective of their colour) have
"cold" light since the radiation is not generated through incandescence
and their spectral distribution is far from being Planckian.

Ingo
Victor Roberts
2014-05-09 11:56:13 UTC
Permalink
Raw Message
Post by Ingo Thies
Post by m***@att.net
The Kansas City Star ran an article today (23 March) about CFL and LED
lamps. It starts out with some good points about lumens and color
temperature, and how CFLs compare to LED. It also mentions the
Thanks for the link. However, I am wondering why apparently everyone is
using the Kelvin scale "upside down", i.e. keeps labelling light with
high colour temperature as "cooler", without any further explanation of
this paradox.
It's a measure of how the light makes you feel. In that way it
follows the artist's rule.
Post by Ingo Thies
But when dimming an incandescent/halogen lamp it is
obvious that dim red (low current through the filament) is cooler than
bright white (full current), as well as noon sunlight (CCT about 5500 K
in summer at sea-level) ist hotter than the reddish light during sunset
(you can actually feel the difference!).
The artist's rule "blue=cold" and "yellow/red=warm" may apply to
surface/pigment colours or subjects of paintings (e.g. water vs. fire),
but not easily for illumination. Furthermore, the "warmth" of
illumination may also depend on the color-rendering index: The lower the
CRI the "colder" everything may look, especially if skin color is
rendered unnaturally pale.
BTW, technically, both CFL and LED (irrespective of their colour) have
"cold" light since the radiation is not generated through incandescence
and their spectral distribution is far from being Planckian.
Ingo
--
Vic Roberts
http://www.RobertsResearchInc.com
http://www.cflfacts.com
sci.engr.lighting Rogues Gallery http://www.langmuir.org
To reply via e-mail:
replace xyz with vdr in the Reply to: address
or use e-mail address listed at the Web site.

This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission.
Ingo Thies
2014-05-09 14:08:24 UTC
Permalink
Raw Message
Post by Victor Roberts
Post by Ingo Thies
Thanks for the link. However, I am wondering why apparently everyone is
using the Kelvin scale "upside down", i.e. keeps labelling light with
high colour temperature as "cooler", without any further explanation of
this paradox.
It's a measure of how the light makes you feel. In that way it
follows the artist's rule.
But this "artist's rule" seems to apply only to people in the Western
countries, and even there not to everyone. And, as I said, it depends on
the situation. Labelling noon sunlight as "cool" and sunset (on the same
day in the same place) as "warm" contradicts my everyday experience. I
guess there is still a lot or research to be done on this topic.
Synesthesia is a fascinating but - as far as I know - still poorly
understood phenomenon.

I can only agree that tungsten light is warmer then fluorescent of LED
light, but this is because it has a 90% infrared excess and thus more
actual warmth.

I guess that there is also a lot of advertising: "Warm" simply sounds
good, and 2700 K LED light can really look like tungsten light, so it is
tempting to call it "warm". But it actually isn't warmer than 6500 K LED
light.

Ingo

Loading...