White Balance: Examples past and present

After the recent snow we've been having, what could be better than using something white as an example of how scenes are affected by choosing different white balances. So I stepped out into the cold yesterday around late morning/early afternoon time, with the intention of spending a good hour in and around Debdale Park, Gorton, just ten minutes from my home. I was sans gloves, so I was back after half an hour, but below is the best 'snowscape' image shot using different white balance settings.

Auto:
A risk of too many blues in the snow parts (especially in the shadows). Sky should be blue, snow should be brilliant white.

Cloud:
A lot better. The trees now look more natural: plenty if browns etc. Also, less blue in the shadows that hit the snow.

Shade:
A lot more orange and brown; possibly too much. Interesting to compare them. Looks somewhat old fashioned, like an old colour film or a cheap Christmas card.

Direct Sunlight:
Very crisp, as you would expect from the sun bouncing directly off the brilliant white snow. Also a lot warmer and natural-looking than the Auto. Guess Auto falls short when photographing snowy scenes.

Flash:
Obviously, I wasn't using flash, but this was shot using the WB preset for flash. Not bad. Warmer than the Auto setting, whose function is to remove any colour casts in an image.

Tungsten:

Less said about this the better. Using this setting assumes the scene is lit with a tungsten/incandescent bulb, thus it aims to remove any red/orange casts. The result- however- is a very cool blue image. 

This is a subject of photography that has caused me considerable trouble when I was an absolute beginner, due to both a lack of understanding and a beginner's desire to control every last thing on my camera (which- with very little understanding of something as important as White Balance- drew me into very murky waters indeed). I used to think White Balance was about setting my camera to reflect the dominant colour in a scene, thus providing images with an unwanted tint. So instead of using my camera to collect the colour cast I was using it to apply one. Below are some 'schoolboy errors' from the early days (2yrs ago).

All-in-all a good portrait, but I went through a phase of constantly changing the white balance for different scenes, and also different people, especially Tungsten and Fluorescent.

So, if I was changing the white balance to match the lighting in different scenes, this was one of the disasters that occurred while shooting neon lights using a fluorescent WB.

Not only was I 'toying around' with different White Balance settings, but also 'tinkering' with the colour temperatures within these settings (below is an example of the intricacy of this system), further confusing my schoolboy mind. I'm not beating myself up over it any more, though. On the level one course they used to call me 'White Balance' Jon because it was evident I had been messing around with it. But I'm a bigger and better photographer now, and doesn't everyone get a little overzealous with things they've just learned? I refer here to the amount of people who overdo things on Photoshop, like selective colouring. Fair play to them, I say! And also good luck!

Within each WB preset is also a the above graph, which I can only presume refers to more specific  colour temperatures. Of course, 'presume' is all I can do, for I do not possess a Masters degree in Thermo-dynamics or statistics. Some things are best left, I feel.

White Balance & Colour Temperature

White Balance exists to ensure the colours in an image are as accurate as possible (1). It provides an adequate reference point used by the camera to correct any harsh colour casts in an image that occur as a result of the dominant light in the shooting situation. For instance, a white wall lit by a halogen light may result in a yellow colour cast, whereas another type will result in a different cast. This is because- unlike the human eye- the camera lacks the intelligence to automatically adjust itself to different colour temperatures.

Colour temperature is a means of quantifying different types of light (and the light radiated from objects shot under that light). It is measured using the Kelvin (K) scale, which attempts to assign different colour temperatures to a range of common scenes and light sources. Below is a a representation of the Kelvin scale.

The Kelvin scale is used in digital photography (film is different 'kettle of fish' entirely) as a guide to the warmth or coolness a scene. This guide is inseparable from White Balance.  Notice how the lower the number, the warmer the colour.

Our cameras come with White Balance settings used to reflect some of the common lighting scenarios we may find ourselves in (e.g. Direct Sunlight, Tungsten, Shady, Cloudy and Auto). Each setting will give completely different (and very interesting) results. As an example, below are two basic images I shot nearly two years ago using different White Balance settings:

Tungsten/Incandescent:
Choosing this for a scene counterbalances the warmth of the light inside the indoor market, thus rendering the scene very cool.

Cloudy:
I don't know why I chose to shoot this as cloudy here, but in retrospect it  works as a nice comparison. Choosing  this setting assumes there is a cool light present from an overcast sky, thus warming the scene. 

Shooting images in RAW means we can change the image's white balance afterwards by opening it in Adobe Camera Raw, affording us more control over the overall result. For this reason, many people suggest choosing the Auto White Balance (AWB) setting in-camera, then either choosing one of the white balance presets or using the scale provided in ACR. Below is an image shot in RAW using AWB, followed by the same image processed with different white balance settings in ACR:

Auto White Balance (5200k):
Note how Adobe Camera Raw details the temperature as 5200k when the AWB is used in-camera.

2500k:
This is the same image after reducing the temperature to 2500k in ACR. This should give a decent idea of how cooler such a change makes.

Shade (7500k):
And this is after choosing the Shade present in ACR. Note 'shade' is given a value of 7500k on the Kelvin Scale. On the whole, it looks like the Auto setting has it pretty exact in this case.

It is also possible to set the White Balance manually on my camera (Nikon D3100). Unfortunately, this doesn't seem to be working on my camera at the moment, but I will endeavour to update this post as soon as it is back up and running.

1)  http://digital-photography-school.com/introduction-to-white-balance