jason elias color temperature

From TakeGreatPictures.com
American Photo and Popular Photography's
Joint Website

WHY SO BLUE, GEORGE?
IT'S THE COLOR TEMPERATURE, IRA.

An examination of Color Temperature
and Why It's Important to Your Photography

So let's get right to it and talk some fundamentals of lighting. I thought we might kick around one of the properties of light that affects every shot you'll ever take, is as important as framing or focus and yet gets no airtime whatsoever.

It's Color Temperature and if you ever want to shoot and date hot models, it's something you need to understand.

So what is Color Temperature exactly and how does it affect my shooting? Well, I'm so glad you asked...

A hundred years ago there lived an old British gent named Lord Kelvin. He was one of these late 19th century renaissance men - physicist, inventor and all-around know-it-all - the type you do not want to get cornered by at a cocktail party. (As far as knowing it all, he entered the debate against Darwin's evolution firmly "on the side of the angels.")

Occasionally though, he got it right and thus was the color temperature scale born.

Kelvin first recognized that when you heated a carbon rod to extreme temperatures, it began to glow (imagine a heated iron rod). As the temperature of this bar rose, the color it glowed shifted as well.

Kelvin realized that there was a direct correlation between the temperature of the bar and the color it glowed. For example, at 2500 degrees the bar always glowed reddish-orange while at 6000 degrees the bar consistently glowed blue-white. He also realized that as the bar temperature rose, the color of the glow rose through the colors of the spectrum.

Now, for those of you who had senior ditch day on the afternoon professor Thomas discussed the light spectrum, it goes something like this...

All the colors of visible light (the colors of the rainbow) get their different color - or frequency - from the fact that the light is traveling at different wavelengths. These different wavelengths correspond to different colors. For example red light has a very long, lower energy wavelength, while blue has a much shorter, higher energy wavelength.

White light, which the sun gives off, is the entire spectrum of different wavelengths combined and this appears to our eye as white. But let the sun hit the crystal your hippy Uncle Ken sent you for Christmas and you'll see the colors spread out again as the crystal acts as a prism breaking the light down into its individual wavelengths. And they spread out in an order of lower wavelength to higher wavelength.

An easy way to remember the order is by using an acronym - ROY G. BIV - Red, Orange, Yellow, Green, Blue, Indigo, and Violet. Pretty easy. (And someone should tell Uncle Ken that selling bongs at the swap meet does not constitute a "real job".)

It was Lord Kelvin who first worked out this scale of colors and their corresponding temperatures of the heated carbon bar. Not surprisingly, like a lot of these old gummers who did something of questionable import, he named the scale after himself. And thus was born the Kelvin Color Temperature Scale - an absolute scale where different colors of light can be described and measured.

A specific Light's color on the scale is known commonly today as it's "color temperature." And this is simply done by matching it to the color of the glow and corresponding temperature of Kelvin's heated bar.

What the hell does this have to with my photography? Well, quite a bit actually.

Our eyes, through millions of years of evolution (angels or not), have developed into amazing tools. Our primitive ancestors lived in varied environments - jungles and deserts, caves and savannahs - and they had to constantly deal with differing lighting conditions they needed to see in just in order to survive. Consequently, their eyes developed into extremely adaptable tools able to discern things in all types of lighting conditions.

Not only that, their brain had to process that information quickly - checking for any hidden lions to run from - under different lighting conditions with light of different color temperatures. So their brains developed a set of internal color filters which removed the relative color of the light and adjusted our perception so that everything looked like it was in white light.

That's why today our eyes adjust to changing lighting conditions. Think back the last time you went to the local Italian dive. When you first walked in it seemed red and dark but after a few moments (typically 3-5 minutes) everything readjusted itself so that you could see relatively normally (our ears unfortunately never did the same, so enjoy the mandolin music...).

As our eyes constantly adapt to changing lighting conditions, shifts in the color of the light (different color temperatures) are not always apparent.

But sometimes, if you watch closely, you can catch it. Try looking at a few different types of light together - sunlight, lamp-light, firelight, fluorescent light - if you trust your eyes, you can see the difference. Yes, that fluorescent does look slightly green. Yes, that table lamp does look orange. Yes, after walking outside things do look a bit blue for a few moments (more about the different colors that different light put off a bit later).

It's actually a very cool process once you trust your eyes enough to see it. It's also a major step towards understanding lighting in a way that most people never even know exists.

Our good friends at the film manufacturing companies (and their digital counterparts who have adopted their parameters) have known all of this about light and its changing color temperature for years. Even so, evolution had a huge head start so as of yet they haven't made one single, defining film or camera setting that is instantly adaptable to all lighting conditions or Color Temperatures.

And although the AWB (Auto-White Balance) setting does adapt, at times its adjustment can be incorrect. And even still, there is no way to adjust for lights of different color temperatures in the same shot.

Film emulsion is specifically sensitive and exposes correctly for only one certain type of color of light. This is called balancing. For example, when a film is balanced for daylight, it exposes correctly for light that has the spectrum - or color temperature - that corresponds to daylight. And since it cannot adjust like our eyes do, all other types of light will photograph as different colors - table lamps, with their lower color temperature light will appear orange, and fluorescents will appear green.

Film manufacturers, realizing this obstacle and wanting to sell as much film as possible, have done tons of research and spent millions upon millions of dollars to figure out what color temperature they should balance the majority of their film for. So they evaluated what type of shooting most people in the world were doing.

After all their research and focus groups, color balancing international panels and technical chemistry-emulsion world-wide forums, they discovered that their prime shooter was not in fact Steve McCurry shooting with the Mujahadeen Rebels in Central Afghanistan for National Geographic.

It was in fact your Auntie Phyllis visiting Disneyland taking a shot in front of the Matterhorn. That was who was taking most of the photos in the world. And that was the scenario they decided they were going to make most of their film for - daylight, exterior. And that's what most film you can buy is balanced for, daylight color temperature.

But, you might ask, if that were true, why would most of the stuff you shoot, whether indoors or outdoors, look normal even when you don't adjust for the changing color temperatures? Well dear friends, that is a cheat on the part of the photo-labs and digital cameras we all use.

The labs use filters while printing our photos making it seem as if we had film that had actually adjusted to the light. And our digital cameras silently and secretly take readings to test the Color Temperature of the light.

But sometimes if you are aware enough you can still catch the difference, the image out of balance. In shots where there are two different types of lights those filters and adjustments don't work all the way. That's why when you shoot someone outside, the lights in the house turn an ugly yellow. Or why, when shooting inside, the windows onto the backyard look a bit bluer.

Now that we understand what color temperature is, how can we start using it as one of the tools at our disposal?

Let's start with the most basic of films and settings, the daylight balance. Daylight, as I mentioned before, is constantly shifting in color temperature - morning, noon, overcast, sunset. But there is a standard daylight color temperature established by the government (who else?). And because control and power is what Washington is all about, the nameless, faceless bureaucrats milling in marble halls dictated the standard daylight color temperature as the color temperature of sunlight at noon on a cloudless day in Washington D.C. (sorry Columbus, Ohio).

After a few readings outside, they determined the color temperature of sunlight as 5600 degrees Kelvin, or 5600K. (In the past years, due to smog in D.C., the temperature has changed to around 5400K and there was a movement to change the accepted standard, but they decided it would be too much of a pain in the ass. Your tax dollars at work.) So that is how daylight film came to be rated for 5600K.

But what about all of the other types of lights? And how can we use color temperature for different effects? How can we balance different lights so they appear white?

Well, that is a huge topic, one that we can discuss at great length another time. But as I said at the beginning, color temperature is extremely important and should be at least thought about during every shoot. So as a small primer...

Sunlight, having a color temperature of 5600K, has a relatively short, high-energy wavelengths - the light is fairly blue. Incandescent light from light bulbs in your home has much longer, slower wavelengths. This is in part due to the fact that a light bulb burns at a much cooler temperature (heat-wise) than the sun (try changing the sun with your hand wrapped in your t-shirt).

This lower burning temperature leads to a lower color temperature - between 2800K and 2900K - which means the light has much more red, orange and yellow in it than that of sunlight (remember ROY G. BIV?). Fluorescents on the other hand, at least the ones you find in most offices, are all screwy. They have a spike of green color temperature and a very poor spectrum in terms of other light.

Here's a partial list of some common lights and their color temperatures -
Candle - 1900K
Dusk or Dawn - 2000K-2500K
Household Lightbulbs - 2800K
Tungsten Lightbulbs - 3200K
Late afternoon - 4500K
Daylight Standard - 5600K
Summer Shade/Overcast Sky - 7000K
Color TV - 9300K

So what can you do about these different color temperatures? And how can we use 'em or change 'em?

The easiest way might be to use a filter on your camera. That can roughly mimic the way our internal evolutionary filter adjusts the light for our eyes. And there a number of great filters we should all carry in our bags.

For the digital shooters out there, it can be much simpler. The camera usually has settings such as Daylight, Indoor, Tungsten and the greatest cheat of all Auto-White Balance .

But in certain situations, those are just patches to get you through the single shot. Many times, especially when shooting Commercial or Fashion, Color Temperature becomes much more critical (gotta make sure that Cerulean Ocean Blue Mini-Skirt comes out absolutely Cerulean Ocean Blue).

And that's where lighting techniques again come into play.

And that's a discussion for another time...

www.jasonelias.com email: jason@jasonelias.com
FromTakeGreatPictures.com American Photo and Popular Photography's Joint Website
From TakeGreatPictures.com American Photo and Popular Photography's Joint Website WHY SO BLUE, GEORGE? IT'S THE COLOR TEMPERATURE, IRA. An examination of Color Temperature and Why It's Important to Your Photography So let's get right to it and talk some fundamentals of lighting. I thought we might kick around one of the properties of light that affects every shot you'll ever take, is as important as framing or focus and yet gets no airtime whatsoever. It's Color Temperature and if you ever want to shoot and date hot models, it's something you need to understand. So what is Color Temperature exactly and how does it affect my shooting? Well, I'm so glad you asked... A hundred years ago there lived an old British gent named Lord Kelvin. He was one of these late 19th century renaissance men - physicist, inventor and all-around know-it-all - the type you do not want to get cornered by at a cocktail party. (As far as knowing it all, he entered the debate against Darwin's evolution firmly "on the side of the angels.") Occasionally though, he got it right and thus was the color temperature scale born. Kelvin first recognized that when you heated a carbon rod to extreme temperatures, it began to glow (imagine a heated iron rod). As the temperature of this bar rose, the color it glowed shifted as well. Kelvin realized that there was a direct correlation between the temperature of the bar and the color it glowed. For example, at 2500 degrees the bar always glowed reddish-orange while at 6000 degrees the bar consistently glowed blue-white. He also realized that as the bar temperature rose, the color of the glow rose through the colors of the spectrum. Now, for those of you who had senior ditch day on the afternoon professor Thomas discussed the light spectrum, it goes something like this... All the colors of visible light (the colors of the rainbow) get their different color - or frequency - from the fact that the light is traveling at different wavelengths. These different wavelengths correspond to different colors. For example red light has a very long, lower energy wavelength, while blue has a much shorter, higher energy wavelength. White light, which the sun gives off, is the entire spectrum of different wavelengths combined and this appears to our eye as white. But let the sun hit the crystal your hippy Uncle Ken sent you for Christmas and you'll see the colors spread out again as the crystal acts as a prism breaking the light down into its individual wavelengths. And they spread out in an order of lower wavelength to higher wavelength. An easy way to remember the order is by using an acronym - ROY G. BIV - Red, Orange, Yellow, Green, Blue, Indigo, and Violet. Pretty easy. (And someone should tell Uncle Ken that selling bongs at the swap meet does not constitute a "real job".) It was Lord Kelvin who first worked out this scale of colors and their corresponding temperatures of the heated carbon bar. Not surprisingly, like a lot of these old gummers who did something of questionable import, he named the scale after himself. And thus was born the Kelvin Color Temperature Scale - an absolute scale where different colors of light can be described and measured. A specific Light's color on the scale is known commonly today as it's "color temperature." And this is simply done by matching it to the color of the glow and corresponding temperature of Kelvin's heated bar. What the hell does this have to with my photography? Well, quite a bit actually. Our eyes, through millions of years of evolution (angels or not), have developed into amazing tools. Our primitive ancestors lived in varied environments - jungles and deserts, caves and savannahs - and they had to constantly deal with differing lighting conditions they needed to see in just in order to survive. Consequently, their eyes developed into extremely adaptable tools able to discern things in all types of lighting conditions. Not only that, their brain had to process that information quickly - checking for any hidden lions to run from - under different lighting conditions with light of different color temperatures. So their brains developed a set of internal color filters which removed the relative color of the light and adjusted our perception so that everything looked like it was in white light. That's why today our eyes adjust to changing lighting conditions. Think back the last time you went to the local Italian dive. When you first walked in it seemed red and dark but after a few moments (typically 3-5 minutes) everything readjusted itself so that you could see relatively normally (our ears unfortunately never did the same, so enjoy the mandolin music...). As our eyes constantly adapt to changing lighting conditions, shifts in the color of the light (different color temperatures) are not always apparent. But sometimes, if you watch closely, you can catch it. Try looking at a few different types of light together - sunlight, lamp-light, firelight, fluorescent light - if you trust your eyes, you can see the difference. Yes, that fluorescent does look slightly green. Yes, that table lamp does look orange. Yes, after walking outside things do look a bit blue for a few moments (more about the different colors that different light put off a bit later). It's actually a very cool process once you trust your eyes enough to see it. It's also a major step towards understanding lighting in a way that most people never even know exists. Our good friends at the film manufacturing companies (and their digital counterparts who have adopted their parameters) have known all of this about light and its changing color temperature for years. Even so, evolution had a huge head start so as of yet they haven't made one single, defining film or camera setting that is instantly adaptable to all lighting conditions or Color Temperatures. And although the AWB (Auto-White Balance) setting does adapt, at times its adjustment can be incorrect. And even still, there is no way to adjust for lights of different color temperatures in the same shot. Film emulsion is specifically sensitive and exposes correctly for only one certain type of color of light. This is called balancing. For example, when a film is balanced for daylight, it exposes correctly for light that has the spectrum - or color temperature - that corresponds to daylight. And since it cannot adjust like our eyes do, all other types of light will photograph as different colors - table lamps, with their lower color temperature light will appear orange, and fluorescents will appear green. Film manufacturers, realizing this obstacle and wanting to sell as much film as possible, have done tons of research and spent millions upon millions of dollars to figure out what color temperature they should balance the majority of their film for. So they evaluated what type of shooting most people in the world were doing. After all their research and focus groups, color balancing international panels and technical chemistry-emulsion world-wide forums, they discovered that their prime shooter was not in fact Steve McCurry shooting with the Mujahadeen Rebels in Central Afghanistan for National Geographic. It was in fact your Auntie Phyllis visiting Disneyland taking a shot in front of the Matterhorn. That was who was taking most of the photos in the world. And that was the scenario they decided they were going to make most of their film for - daylight, exterior. And that's what most film you can buy is balanced for, daylight color temperature. But, you might ask, if that were true, why would most of the stuff you shoot, whether indoors or outdoors, look normal even when you don't adjust for the changing color temperatures? Well dear friends, that is a cheat on the part of the photo-labs and digital cameras we all use. The labs use filters while printing our photos making it seem as if we had film that had actually adjusted to the light. And our digital cameras silently and secretly take readings to test the Color Temperature of the light. But sometimes if you are aware enough you can still catch the difference, the image out of balance. In shots where there are two different types of lights those filters and adjustments don't work all the way. That's why when you shoot someone outside, the lights in the house turn an ugly yellow. Or why, when shooting inside, the windows onto the backyard look a bit bluer. Now that we understand what color temperature is, how can we start using it as one of the tools at our disposal? Let's start with the most basic of films and settings, the daylight balance. Daylight, as I mentioned before, is constantly shifting in color temperature - morning, noon, overcast, sunset. But there is a standard daylight color temperature established by the government (who else?). And because control and power is what Washington is all about, the nameless, faceless bureaucrats milling in marble halls dictated the standard daylight color temperature as the color temperature of sunlight at noon on a cloudless day in Washington D.C. (sorry Columbus, Ohio). After a few readings outside, they determined the color temperature of sunlight as 5600 degrees Kelvin, or 5600K. (In the past years, due to smog in D.C., the temperature has changed to around 5400K and there was a movement to change the accepted standard, but they decided it would be too much of a pain in the ass. Your tax dollars at work.) So that is how daylight film came to be rated for 5600K. But what about all of the other types of lights? And how can we use color temperature for different effects? How can we balance different lights so they appear white? Well, that is a huge topic, one that we can discuss at great length another time. But as I said at the beginning, color temperature is extremely important and should be at least thought about during every shoot. So as a small primer... Sunlight, having a color temperature of 5600K, has a relatively short, high-energy wavelengths - the light is fairly blue. Incandescent light from light bulbs in your home has much longer, slower wavelengths. This is in part due to the fact that a light bulb burns at a much cooler temperature (heat-wise) than the sun (try changing the sun with your hand wrapped in your t-shirt). This lower burning temperature leads to a lower color temperature - between 2800K and 2900K - which means the light has much more red, orange and yellow in it than that of sunlight (remember ROY G. BIV?). Fluorescents on the other hand, at least the ones you find in most offices, are all screwy. They have a spike of green color temperature and a very poor spectrum in terms of other light. Here's a partial list of some common lights and their color temperatures - Candle - 1900K Dusk or Dawn - 2000K-2500K Household Lightbulbs - 2800K Tungsten Lightbulbs - 3200K Late afternoon - 4500K Daylight Standard - 5600K Summer Shade/Overcast Sky - 7000K Color TV - 9300K So what can you do about these different color temperatures? And how can we use 'em or change 'em? The easiest way might be to use a filter on your camera. That can roughly mimic the way our internal evolutionary filter adjusts the light for our eyes. And there a number of great filters we should all carry in our bags. For the digital shooters out there, it can be much simpler. The camera usually has settings such as Daylight, Indoor, Tungsten and the greatest cheat of all Auto-White Balance . But in certain situations, those are just patches to get you through the single shot. Many times, especially when shooting Commercial or Fashion, Color Temperature becomes much more critical (gotta make sure that Cerulean Ocean Blue Mini-Skirt comes out absolutely Cerulean Ocean Blue). And that's where lighting techniques again come into play. And that's a discussion for another time...
	DAYLIGHT 5600 K In this first photo, I shot my good friend Heather under natural WHITE LIGHT. I used color corrected Lights that matched the color temperature of daylight - 5600 K(elvin) and shot film that was rated for daylight, as most films are. Notice how her skin tones are correct as well as the wood behind her.

	TUNGSTEN 3200 K In this second photo, I shot film that was rated for Daylight but instead of Daylight balanced Lights, I instead used Tungsten Lights which have a color temperature of 3200 K. These lights have a much warmer color temperature than Daylight and as you can see, with Daylight film the Tungsten lights cause the photo to have a much more yellowish/reddish tint to it. Notice how the wood behind Heather has turned almost completely red.

	FLUORESCENT (GREEN) Here I turned off all the Lights and shot under a regular Fluorescent light mounted in the ceiling. The tubes in the light were a standard cool white and you can see how green the film reads it as. Notice how unappealing the fluorescent is on skin tones, giving a sickly pall. Not good...unless that's the mood you are looking for.

	DAYLIGHT/TUNGSTEN MIX In this photo I used both Daylight balanced lights as well as Tungsten lights. The Daylight is in the foreground on Heather, giving her face and skin natural color and tone. I used Tungsten on the background wood and you can see how yellow and red it reads on Daylight balanced film.

	SUNSET 2500-3500 K In this final photo, I partially opened the window-shade as the sun was going down. You can see how the setting sun starts to turn from the White Light of the daytime (5600 K) to the warm, beautiful light of sunset. This is right around what many photographers call "magic hour" - the time just before sunset, when the light is warm and rakes at a nice steep angle, until after the sun has actually set but there is still a soft golden light in the sky. Here you can see how the angle of the light, combined with the warming color temperature of the setting sun, leads to dramatic photos. Notice how the light with this warmer color temperature also causes skin to take on a healthy glow.
	Copyright Jason Elias 2006