Before we get into this discussion of what color temperature is I should explain the Kelvin scale. Color temperature is rated in degrees k (k in lower case) on the Kelvin scale which was invented by Scottish scientist William Thompson (Lord Kelvin). I am not going to get into a discussion on how William Thompson arrived at this scale but if you are interested you can do a Google search on him and there is plenty of information available on the subject.
The color temperature scale will apply to all color photography but white balance is only adjustable in post processing if you shoot RAW.
What is color temperature ?
The chart provided above indicates that 5500 degrees k is daylight. Anything lower than 5500 degrees k will impart a yellow to red quality of light to your images and anything higher will impart a blue quality. If you remember in previous lessons I stated that I take a lot of images around “Golden Hour”. If you look at the Kelvin scale you will see that Sunrise/Sunset and Golden Hour are on the warm side of the scale and the quality of light is on the yellow to orange. The example below will verify how the quality of light (or color temperature) will correspond with the kelvin scale.
The above photo was taken right after sunrise and the color temperature is about 3300 degrees k. If you look at the Kelvin scale at 3300 k you will see what color light influenced the above image.
I know the above explanation is fairly basic but I think it is easy enough to understand just by looking at the chart.
Why should I worry about color temperature because the camera seems to do a good job adjusting it on its own ?
The camera does a very good job of adjusting white balance on its own and I suggest you leave it Auto white balance. I am suggesting that you shoot RAW rather than jpg files because if the camera is slightly off with its white balance choice at least you can correct it in post processing.
But my camera is always spot on and I never feel the need to adjust white balance Joe.
That might be true but you must be very lucky because sooner or later you will have to adjust white balance to achieve proper color. I will show you a couple of examples below and while the white balance is only slightly off it makes a big difference when working with a color calibrated monitor (as I am) and if you print your photos. Most people do not see white balance problems until they print their image and waste expensive photo paper.
In the above example this is a pretty straight forward image of some flowers and the camera did a pretty decent job with the white balance 4750 degrees k. Upon a closer inspection you might notice the white petals take on a bluish green tint because of the light reflected off the background foliage.
In this example I corrected the white balance by raising the color temperature in Lightroom to 5100 degrees k which is more like the scene I saw with my eyes. Even though the color temperature was only raised by 350 degrees k the white petals are more correctly displayed.
In this example I changed the color temperature to daylight in Lightroom 5500 degrees k but I think its a little too much to my liking so the second example looks more correct to me. Some of you might not even notice these changes I am making because you are using a small screen or a notebook computer but I can assure you with a 27′ monitor like the size I am using the changes are plain as day.
Let me show you a different example.
This image was taken in Niagara Falls from the Canadian side and the image looks pretty good. I didn’t like the bluish tint to the spray and the water coming over the falls. This photo was taken on Auto white balance at 4950 degrees k. Lets try to correct that water in the next image.
This is a little bit better the water is closer to the original color and the spray looks whiter. The surroundings look like mid April in Ontario (when this image was taken) before the leaves started growing on the trees. This was corrected to daylight or 5500 degrees k in Lightroom.
If you shoot RAW files you should try going back into your photo archives and try to find some that might benefit from a small white balance adjustment.