LED color question...
- Thread starter PJD
- Start date
Help Support Candle Power Flashlight Forum
KC2IXE
Flashaholic*
I always thought it was Bluey Green
Lux Luthor
Flashlight Enthusiast
Max
Enlightened
Blue light + green light makes cyan.
INRETECH
Flashlight Enthusiast
INRETECH
Flashlight Enthusiast
PhotonRanger
Newly Enlightened
This is a good description for light: http://www.csupomona.edu/~jcclark/classes/bio542l/essays/colorwheel.html
Additive primaries red - blue - green
Subtractive primaries yellow - magenta - cyan
Painters using pigment have a different color wheel, where the primary colors are red, blue and yellow. Mixing the primary colors creates the secondary colors. Red mixed with blue creates violet, red mixed with yellow creates orange, and yellow mixed with blue creates green.
Some painters (like my ex) are snotty enough to call this the "real" color wheel. Of course she also thought artists using cameras (like me) shouldn't call their artwork photography as it would "ghettoize" it, but I digress.
Additive primaries red - blue - green
Subtractive primaries yellow - magenta - cyan
Painters using pigment have a different color wheel, where the primary colors are red, blue and yellow. Mixing the primary colors creates the secondary colors. Red mixed with blue creates violet, red mixed with yellow creates orange, and yellow mixed with blue creates green.
Some painters (like my ex) are snotty enough to call this the "real" color wheel. Of course she also thought artists using cameras (like me) shouldn't call their artwork photography as it would "ghettoize" it, but I digress.
EMPOWERTORCH
Enlightened
Technically speaking, cyan is the colour of light whose wavelength is about 555nm.
This happens to be the optimum wavelength that the human eye works at!
Torches which employ this light colour are very effective even with low level light output. It is also the colour of the most efficient and powerful LED's.
This is also the reason for making it the standard colour for my torches...cyan is hugely popular with all my customers!
For a general purpose light source which doesn't necessarily need good colour rendering, it cannot be beaten! Maybe one day all streetlighting could use this colour as it is far more visible than the yellow or pinkey-yellow of sodium bulbs!
This happens to be the optimum wavelength that the human eye works at!
Torches which employ this light colour are very effective even with low level light output. It is also the colour of the most efficient and powerful LED's.
This is also the reason for making it the standard colour for my torches...cyan is hugely popular with all my customers!
For a general purpose light source which doesn't necessarily need good colour rendering, it cannot be beaten! Maybe one day all streetlighting could use this colour as it is far more visible than the yellow or pinkey-yellow of sodium bulbs!
Lux Luthor
Flashlight Enthusiast
<font size="2" face="Verdana, Arial">Anyone got a link to a discussion of the physics or chemistry of why this is an efficient color for LEDs to produce?</font><hr /></blockquote><font size="2" face="Verdana, Arial">There's some good information on Don Klipstein's page here. I don't recall if discusses cyan, though.
Lux Luthor
Flashlight Enthusiast
<font size="2" face="Verdana, Arial">I have 2 ambers. The older one I have has a fair amount of orange in it. The newer one doesn't, and actually is a very beautiful color when used for area lighting, such as in a tent or to dimly light a room. I'm not sure if the difference is due to the luck of the draw, or some design changes.
INRETECH
Flashlight Enthusiast
I don't think its really the most efficient LED, I think its more because most of the lightmeters and our human eyes are most sensitive in the Green/Yellow range
Mike
www.inretech.com
Mike
www.inretech.com
Wim Hertog
Enlightened
ENDPOWERTORCH,
I really think 555 nm is pure green and not cyan.
Our eyes are indeed the most sensitive at 555nm when it's light enough, but at night they are more sensitive for 505 nm (=CYAN)
I really think 555 nm is pure green and not cyan.
Our eyes are indeed the most sensitive at 555nm when it's light enough, but at night they are more sensitive for 505 nm (=CYAN)
<font size="2" face="Verdana, Arial">Lux, thanks! Lots of interesting stuff!
So...it would appear that because of the coating necessary for a blue LED to produce white light, that the mono-chromatic LEDs like Red, Blue or Green truly are "more efficient" and will give more actual light than white.
and...that a green or cyan light is more easily perceived by the human eye but that perception is more like "black and white" meaning that much of what you "see" is lacking a certain quality of fullness (I notice this myself when walking with a blue-green light, it seems to be not quite as good for "3D").
but...if you JUST NEED SOME LIGHT like you are stuck in a cave or on a dark highway changing a tire, you'll get more light, "brighter" light from a green or cyan source.
plus...if want to be seen (it's dark and don't want to get hit by a car), that more "easily perceived" green or cyan light will be more easily seen by the driver of the car you don't want hitting you!
So...for a back up light or really long lasting light for emergencies look's like green or cyan gets the vote!
Although, if you need your light to distinguish the color of wires in a dark wiring closet or chassis...better stick with white!
INRETECH
Flashlight Enthusiast
The question was:
Mike, the inretech home page shows these listing for "lumens":
18 White
25 Red
25 Green
30 Cyan <--- so, is this "perceived" lumens?
Yes, this is true - the human eye and most lightmeters are not sensitive to the colors linearly
http://www.inretech.com/pictures/response.jpg
We have approx 120 Million Rods which are used for Black/White
But only 6 to 7 Million Cones which are packed in a tiny place near the blind spot, which give us "color"
http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html#c4
The human eye is not linear in brightness either, it can not accurately tell the difference from something 2x brighter as something 5x brighter
Mike
www.inretech.com
Mike, the inretech home page shows these listing for "lumens":
18 White
25 Red
25 Green
30 Cyan <--- so, is this "perceived" lumens?
Yes, this is true - the human eye and most lightmeters are not sensitive to the colors linearly
http://www.inretech.com/pictures/response.jpg
We have approx 120 Million Rods which are used for Black/White
But only 6 to 7 Million Cones which are packed in a tiny place near the blind spot, which give us "color"
http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html#c4
The human eye is not linear in brightness either, it can not accurately tell the difference from something 2x brighter as something 5x brighter
Mike
www.inretech.com
INRETECH
Flashlight Enthusiast
The formula for the White LED is not perfect, they still need to get a better color distribution
Here is the color distribution from a typical White LED:
http://www.inretech.com/pictures/whiteled.jpg
As you can see, the LED is really a Blue LED that excites the phosphor, and causes harmonics to occur in the lower frequency (longer wavelengths)
But, this is not a even distribution, or what we are "used" to from the Sun:
http://www.inretech.com/pictures/sun.jpg
Mike
http://www.inretech.com
Here is the color distribution from a typical White LED:
http://www.inretech.com/pictures/whiteled.jpg
As you can see, the LED is really a Blue LED that excites the phosphor, and causes harmonics to occur in the lower frequency (longer wavelengths)
But, this is not a even distribution, or what we are "used" to from the Sun:
http://www.inretech.com/pictures/sun.jpg
Mike
http://www.inretech.com
