Digital Camera Colour and White Balance
Before discussing options for the control of White Balance let’s consider why this so important to photographers. The first to recognise is that all light has a colour depending on its wavelength. This is true of both artificial and natural light. We are recognise this as it gives rise to colour, however light also has a colour temperature which is measured in something called Kelvin or K for short.
Here is the analogy someone once explained to me that helped me better appreciate light temperature. Imaging a bar of steel in a furnace as it starts to heat up. At first you might see it glow red. As it grows hotter it begins to turn white hot before changing to a blue white with the intensity of the heat. The Kelvin scale for light temperature is pretty similar to this. At the lower levels e.g. 3,000k light has a red colour to it and is said to be warm. This is because we associate the red end of the colour spectrum with warmth and the blue end with cold. Increase the colour temperature of the light to around 5,000k and it appears white. Beyond this at perhaps 8,000k and it begins to look blue.
The tricky part for us as humans is that our brain has adapted over the years to compensate for this and light of different Kelvin values can still look white to us. So if you are standing in the shade of a tree the light still appears whit to us when in reality it has a blue colour cast. When we were all shooting colour and slide film this colour cast was something that we often needed to deal with. We did this by balancing it out with coloured filters such as an 81C warming filter. Now with the advantage of the digital camera we can use the AWB (Auto White Balance) to negate this colour shift and render white as white under even quite tricky lighting conditions.
At this point you might be wondering why you wouldn’t want to always compensate for this and simply leave your camera set to AWB as indeed many people do. Well I believe how you chose to deal with the colour temperature of the light in your scene is one of the great artistic decisions a photographer can make. I will explain this further in a moment however I should stress that my perspective is as a landscape photographer dealing with natural lighting at different times of the day and under different weather conditions, all of which will affect colour temperature. The comments can also affect other forms of photography such when shooting an office interior under fluorescent lights which actually create a green hue to the light. In the studio you will use daylight balanced lights which are balanced to around 5,000K so that white appears white. You might also use coloured gels over your lights to control the colour temperature.
So as I say, the colour of light is an artistic decision which you need to take control of. Consider for a moment how we relate colour with emotion; reds and oranges tend to be thought of as warm whilst blue is cold. I can use this to my advantage when shooting outside providing I understand how to take control, something we will discuss shortly. This about photographing a sunset, you want the image to take on a golden colour cast to convey the warmth of the light. Shooting snow scenes or shooting high in the mountains you might want the image to have a blue colour cast to signify cold. This is quite a simplification but it gives you the idea.
How to Control Colour White Balance
We have a number of options open to us including filters, coloured gels, in camera adjustment and RAW adjustment and Photoshop/image editing. I am going to stick my neck out a little here and ignore the filters and coloured gels as the majority of people reading this will be shooting digitally. With digital photography the best options to use are the in camera settings and the RAW conversion tools. Whilst image editing tools can be used with any digitised image I will also ignore those as it’s another subject entirely.
The first decision to take is will you shoot in RAW or JPG. JPG’s are quick and easy but offer limited control of colour temperature. RAW on the other hand has a much greater control but needs an element of post processing.
When shooting in JPG you should take care to select the correct white balance setting in your camera for the scene you are shooting. This is less of an issue when shooting RAW as you have complete control over the colour temperature in your the RAW conversion software. It’s also true however that you can run JPG images through many RAW converters to gain some element of control of the colour. Despite this my own preference is to shoot in RAW.
Digital Camera Control
Most if not all advanced digital cameras provide the capability to control the white balance of the scene i.e. the colour temperature of the light. Most photographers don’t however use this and instead leave the camera set to AWB (Auto White Balance). The purpose of AWB is to remove colour shifts and render white as it would appear at 5,600K (approximately). This is often not a good look for scenes that rely on emotion such as a beautiful sunset on the coast.
The alternative to AWB is to use one of the cameras preset such as shade, daylight, tungsten etc. Now remember, these settings are used to remove the colour shift but can also be used to introduce one. For example if you set the colour white balance to Tungsten your pictures shot in natural daylight at midday will look blue. This is because the usual colour temperature of Tungsten light is 3,000K to 3,500K but daylight has a temperature of 5,600K. By setting the White Balance point in the camera to Tungsten, you will cause images shot in daylight to shift to cooler Blue shades. What the camera is trying to do is to increase the colour temperature of the image so that warm tungsten light becomes a neutral 5,600k daylight. If you are already shooting in daylight it will shift this light temperature up to a higher level (around 8,000K) where it looks blue.
So how can you really use this? The answer is to take control by setting a Custom White Balance in your camera. When you set a custom white balance you are saying to the camera to fix the colour temperature of the light at a given level and treat this as the white point i.e. white is “true white”. There are two ways in which you can use this:
- If you want to ensure you remove any colour cast for the current lighting conditions you can take a white balance reading off something that should be white. This is a great tool in constant lighting conditions such as in the studio.
- If you are a landscape photographer you can set a white balance point at midday under a clear sky with the sun overhead as this should give a true white. Then as the daylight changes through the day due to the angle of the sun or the weather conditions, your camera will reflect this change.
This second approach is the one I use even though I also shoot in RAW and then tweak my colour temperature in the RAW converter. I find setting a custom white balance gives me a known starting point. It’s also quite enlightening to see how different some cameras can be. If you want to set your own custom white balance refer to your cameras manual and you will also need something that’s white to take a reading off. Whilst you could buy a reference cad or disk, my approach is to use a Lee filter cap. These cost only a few pounds and are intended to snap over filter rings on your lens to protect the lens when you don’t have a filter attached. Lee had the foresight to make these semi opaque and white so they could be used for just this purpose. I just take my reference image with the cap in place and the camera pointing to the sky. As the cap is partly opaque it diffuses the light to a nice even spread. Another option which is just a little cheaper is to use the lid off a Pringles tube.
Control in RAW Processing
Shooting in RAW provides huge flexibility in terms of controlling the white balance of your images. RAW converters will typically allow you to change the white balance in a number of ways. Firstly they tend to provide a list of presets that you can try out with your image such as “Auto”, “Sunny”, Cloudy”, “Monochrome” etc. This is just like selecting one of the in camera presets. They are very easy to use and provide some idea of how you might want to adjust the image. They are however quite a coarse adjustment and very unlikely to be as good as a custom adjustment. If you find these settings look unnatural as you change them, try looking away for 10 seconds before considering the impact of the change. Our brain is quite sensitive to these shifts and the longer you look at the image the more you will come to accept the current setting as being correct.
As hinted at above the best way to control the white balance is with a custom setting using the colour temperature slider and a second setting which I will call tint. Remember that RAW converters all tend to work differently but they will all have some way of changing these settings. The colour temperature slider allows you to shift the white balance colour between Blue and Red. In Lightroom or Photoshop the tone adjustment allows you to shift the colour between Green and Pink. In Capture One this tone control has a full colour wheel that you can use to pick a colour. I won’t go into how to use these in this article but once you have experimented for a while they become quite intuitive.
As already outlined, I shoot in RAW using a custom white balance set at mid day. This should allow true whites to appear as white in my image when shot in similar conditions. At sunset the whites would shift towards the red end of the colour spectrum. This you might think would mean minimal adjustment but I still like to adjust the colour temperature and tone values manually to see if I can add a little more felling to the image. I would recommend this approach to you if you haven’t already tried it.
I hope this article has encouraged you to take more control over how you use white balance in your photography and you don’t just gamble on the AWB setting.