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View Full Version : WHY the oxymoronic descriptions of light bulbs?



Kev Williams
02-11-2018, 4:06 PM
Why is it we drive on parkways, and park on driveways?

And why is it that our sun is certainly yellow-ish, and 'cool' colors are blue-ish, but the light output of "cool-white" bulbs is yellow and "daylight" bulbs are blue...?

Lee Schierer
02-11-2018, 4:12 PM
I think it has more to do with color rendering than actual light color. Daylight bulbs generally give colors that are closer to what we see outside on a sunny day.

Adam Herman
02-11-2018, 4:25 PM
if in reference to LED bulbs:

https://en.wikipedia.org/wiki/Color_temperature

because LEDs are doped with phosphors to produce a certain wavelengths of light, and the sun puts out the full spectrum of colors.

also see the charts here: https://www.soundandvision.com/content/led-vs-cfl-bulbs-color-temp-light-spectrum-and-more


more expensive bulbs are generally better. I stick with Cree.

Rod Sheridan
02-12-2018, 7:58 AM
Hi Kev, after your query on "light bulbs" I'm going to tease you about that, they're not "light bulbs", they're lamps :D

As for the red being "warm", it's not in physics, light at the blue end of the spectrum is emitted with more energy by warmer objects than light in the red spectrum.

I think it's because we see fires and red hot objects as warm physically, so we go with what we feel as humans...........Regards, Rod.

Perry Hilbert Jr
02-12-2018, 8:25 AM
Years ago, I had a friend at the same firm that had a peculiar sport coat. Under florescent light it appeared green under sunlight it appeared brown. My wife has trouble distinguishing between black and navy blue under most artificial light. Same for dark green and dark brown. A light bulb that cures this problem would save me from sometimes telling her that her socks don't match.

Jim Koepke
02-12-2018, 11:26 AM
And why is it that our sun is certainly yellow-ish, and 'cool' colors are blue-ish, but the light output of "cool-white" bulbs is yellow and "daylight" bulbs are blue...?

The color spectrum of artificial lamps is often designated in degrees Kelvin. The incandescent lamps of old were a nice amberish glow of about 2700 to 2800 K. Our brain adjusts our seeing so we would see this as making white paper look white.

In the days of using film in photography there were some available for use in artificial light. Lamp color balance in film photography was a bit tricky at times.

Here is a chart that explains it a little:

378913

Other charts may indicate the color metal glows at the various temps.

jtk

Michael Weber
02-12-2018, 12:23 PM
"Good grief", I find the question "seriously funny" but that's just my "unbiased opinion."

Yonak Hawkins
02-12-2018, 2:02 PM
Even though the light from the sun is more toward the yellow spectrum, when it gets bounced around on our planet it tends to turn more bluish because of the nature of the shorter wavelengths. That's why things far away are blue as is our atmosphere (the sky).

Kev Williams
02-12-2018, 4:47 PM
I just searched- everyone explained way 'daylight' is blue, but none of ya's explained why bulbs-- err, lamps- that produce bright yellow light are 'cool white'.

And as to bulbs are lamps and lamps are fixtures-- check most lighting website, they refer to them as 'bulbs' more often than not, because-- WE do :)g

Myk Rian
02-16-2018, 12:37 PM
Lamps do not create light, they suck in the dark, and are called Dark Suckers.

John C Cox
02-16-2018, 1:13 PM
There is no mistake that light bulbs produced very yellow light for a long time.

It's the most efficient color for your eyes... You perceive that the room is much "brighter" for the same lumen output with the yellowy lamps...

The blueish white lamps are opposite... They are more "brilliant" but are extremely inefficient for your eyes... They appear very "white" but it takes WAY WAY more actual lumens before your eyes can do anything useful with it..

Mike Cutler
02-18-2018, 1:20 PM
Kev

Light bulbs don't give off light, they absorb darkness. The speed at which they absorb darkness, determines the color. When they're full, they can't absorb anymore darkness, and that's why it's dark.
It's true! Trust me.:D

Yonak Hawkins
02-18-2018, 3:19 PM
It's true! Trust me.:D

Oh no ! You're sounding like a politician.

Art Mann
02-18-2018, 3:41 PM
Oh no ! You're sounding like a politician.

or maybe a Glowforge Company rep.

Mark Bolton
02-18-2018, 6:22 PM
Years ago, I had a friend at the same firm that had a peculiar sport coat. Under florescent light it appeared green under sunlight it appeared brown. My wife has trouble distinguishing between black and navy blue under most artificial light. Same for dark green and dark brown. A light bulb that cures this problem would save me from sometimes telling her that her socks don't match.

This is our world in wood lol. I joke with employees all the time to just go with thr color match and forget it. You can take a finished board, door, whatever, and move around the shop and watch it change color. Fourescents push green, leds (non color corrected) push white/blue, incandescent yellow, take it to a plate window another color, low e another, outside another, now you add in wall color and the color of reflected light (carpet color on a job can wreak havoc).

Carlos Alvarez
02-20-2018, 2:28 PM
The sun only looks yellow to you because the sky is more blue, in contrast.

Pat Barry
02-20-2018, 3:44 PM
Cool white today is just a carry-over of a marketing term from years ago that attempted to distinguish the fancy new coated light bulbs that looked more "white" in color than the older, uncoated counterparts. Now the term has stuck and the preferred type of LED light for use in most homes is 'cool white', even though the LED bulbs called "daylight" produce even more 'white". I happen to think that "daylight" bulbs work better in my shop than "cool white" because they are apparently brighter (wattage being equal). Now the more proper terms have to do with Kelvin ratings which nobody (most consumers) really understand.

Mark Bolton
02-20-2018, 7:22 PM
Cool white today is just a carry-over of a marketing term from years ago that attempted to distinguish the fancy new coated light bulbs that looked more "white" in color than the older, uncoated counterparts. Now the term has stuck and the preferred type of LED light for use in most homes is 'cool white', even though the LED bulbs called "daylight" produce even more 'white". I happen to think that "daylight" bulbs work better in my shop than "cool white" because they are apparently brighter (wattage being equal). Now the more proper terms have to do with Kelvin ratings which nobody (most consumers) really understand.

The kelvin rating is more an issue of brightness for most (including those who sell them commercially). It has virtually nothing to do with color.

We have some 6500 and 8500 Kelvin fixture in the shop and outside fixtures and at 6500 youd better be prepared to see dead-white and spots in your eyes.

Pat Barry
02-20-2018, 7:37 PM
The kelvin rating is more an issue of brightness for most (including those who sell them commercially). It has virtually nothing to do with color.

We have some 6500 and 8500 Kelvin fixture in the shop and outside fixtures and at 6500 youd better be prepared to see dead-white and spots in your eyes.
Hi Mark,
here is a guide for kelvin ratings vs color
http://www.westinghouselighting.com/color-temperature.aspx

Carlos Alvarez
02-21-2018, 11:08 AM
The kelvin rating is more an issue of brightness for most (including those who sell them commercially). It has virtually nothing to do with color.

We have some 6500 and 8500 Kelvin fixture in the shop and outside fixtures and at 6500 youd better be prepared to see dead-white and spots in your eyes.

What huh? Go talk to a photographer or something. You have that backwards.

Greg R Bradley
02-21-2018, 11:33 AM
The kelvin rating is more an issue of brightness for most (including those who sell them commercially). It has virtually nothing to do with color.

We have some 6500 and 8500 Kelvin fixture in the shop and outside fixtures and at 6500 youd better be prepared to see dead-white and spots in your eyes.
Completely backwards.

Color temp has everything to do with color and nothing to do with brightness.