- Do your indoor photographs come out red or yellow?
- Do your winter photograph seems very blue?
- Do you get weird colours in people’s faces when you shoot portraits in fluorescent light?
You need to learn more about white balance!
When you take photographs the camera records what it sees. This is a difference to our eyes where the eyes themselves and the brain actually processes what we see before we experience it. Light comes in many different aspects. It can be coloured light or it may be even distributed ”white light” across the spectrum. However the distribution across the spectrum can be uneven and the light is then said to have a certain ”color temperature”.
This temperature is measured in a scale called Kelvin, the same that physiscists use to talk about temperature. And when we speak about light temperature we are speaking about something that the phycisists call ”black body radiation”. The explanation for this phenomenon is somewhat complex and out of the scope here so let’s just say that when you heat something up enough it starts to emit light.
If you think about a piece of iron when it is heated enough the light from it is white almost with a blue streak. And when it cools off it becomes first yellow, then orange, then red and after that you can not see the color any more. So physicists talk about various colours as they are related to objects and what colour the radiate at different temperatures. Now we can relate temperature with colour.
Kelvin is not so different from degrees Celsius. There is however an offset of 273,15 (273 will do for us) degrees between the Kelvin scale and degrees Celsius. That is because Celsius has it’s zero point when water freezes (at sea level) and Kelvin has it’s zero point when there is a total absence of energy, the coldest there can be. This point is -273,15 °C so therefore room temperature is close to 300 K. Now, to see something glowing it is generally around 2000 K or more. Light from the sun at mid day can be estimated to have a light temperature of about 5 600 K.
In the evening and in the morning the tones go more pronounced red and yellow, the golden hours as they are called in photography takes place roughly one our after sunrise and one hour after sunset and they are great for nature photography. Light from a light bult is usually somewhere around 3 200 K giving a much more red-yellow light than the sun.
Indoor where we use electrical light the light radiated from these are much colder compared to the sun. Our brains adjust to this automatically but not our cameras necessarily. There is a control on the camera called White Balance. This control tells the camera what the temperature should be of the main light source in the picture and the camera will adjust the red-blue balance of the picture accordingly.
Today most cameras have automatic detection of white balance but this can sometimes be wildly wrong so it is always a good thing to try to learn to set this yourself. Most cameras today have several settings for white balance, here are some that are common on most cameras:
- Automatic mode
- Bulb light
- Fluorescent light
- Flash light
If you are photographing in RAW format you don’t need to worry about these, because you can always set them in your post processing of the pictures. But if you are shooting in JPEG format you should take care and try to get the white balance right from the beginning. If you fail to do this you may compensate a little bit in your post processing software (Google Picasa, Adobe Lightroom, Photoshop, GIMP or the tool of your choice) but when you do that to a compressed picture such as a JPEG there will be artefacts introduced. Slight adjustments are okay but if you need to change it more than a few hundred Kelvin then you will notice you start getting strange things in your picture.
One example is the sudden appearance of bright blue pixels in dark or black areas. It does not look good.
At the same time there really is no need to fully compensate for white balance, sometimes the blueish or reddish tone can actually make the picture a very nice picture but if you are tired of having every picture you shoot indoor come out as yellow-orange then you need to find and adjust your cameras white balance setting.
It should be fairly obvious which setting goes where, after all the names says it all. At this point I want you to look up your camera’s manual and find the chapter on white balance. Take a few test shots with different settings and learn the difference between them.