White evenly distributed
Funny that we have this thing called white balance, as it in most cases is not necessarily about white. So, what is white balance exactly then? It is more the balance of colors and one would change it, to make a photo look more natural. Now, you might ask: if I see it a certain way, then the camera will take the photo also like that, right? By now, everybody who has read a few of my previous posts knows I will answer that with a no. And it is indeed no. Basically all lights are not pure white. They have a different temperature. And temperature is indeed the term here as it is expressed in Kelvin. An object would be called white, if it reflects all wavelengths. And black, if absorbs everything and reflects nothing at all. However, white light is not always reflecting all wavelengths with the same strength. And here is where that temperature comes in.
|Couple on a bench|
If you have a low temperature, say 1500 Kelvin, as from a candle, it will be more intense with the higher wavelengths, like red and orange. A high temperature 9000 Kelvin, as one would have from a heavy overcast sky, would be more intense with the magenta and blue wavelengths. Funnily enough, we call the high temperature cool and the low temperature are the warm colors.
The difference between us and a camera, is that we, or our brain to be more specific, partly compensates for this difference. And as such we will perceive people with a normal skin color during sunset, which has light with a temperature of around 3000 Kelvin, but also when standing in the office, where the fluorescent lamps will have a temperature of 5000 Kelvin. That's pretty cool from our brain, right? And for the people thinking I would once again say no: you're wrong. This is pretty cool.
The camera has no brain and does not compensate. Therefore a photo from one person in the sunset and one in the office will give different skin colors. And here comes the part about white balance. By setting the white balance on the camera, you tell your camera to compensate for the different light sources.
Changing this delicate balance
Now we know that different light conditions will show our photos with different tones. How important is that? If you look at the photo in the previous paragraph, you'll probably get a complete different feeling than from the photo below.
|White balance as shot|
It is the obviously the same photo. But the first one is much warmer. I admit this is not just the white balance, though. But it has a part in it. The photo in this paragraph is the one with a white balance as shot by the camera. You can argue which one has the more natural colors and I suppose most people will point at this second one. Even if it is a little too cool (or in other words has a small too blue tint), The one at the top has too much orange. As it should be, as I - besides changing the white balance - overlaid the photo with an orange tint.
You are by now probably frowning and wondering why I gave that example then? Well, two reasons. The first is a form of vanity. I edited this way, because I like it that way. And therefore I also like to show it that way. The second is that it, just by its exaggerated warmth, shows the effects white balance can have. The top one approaches the effect one could have from a nice orange sunset. It also shows that one might change the white balance to get a bit away from the original colors.
Setting white balance
|White balance corrected for daylight|
If one would be shooting RAW, one would not care much about it. The camera will keep all color information and then you can adjust it in your post processing software. After all, when shooting RAW, post processing is not really an option, but a must. If you have a camera that cannot shoot RAW, or you do not want to shoot RAW, you need to set the correct value, if possible. If you have it on auto, or no option at all, the camera will examine your photo and using its programmed algorithms to set the white balance. If I recall correctly, for my Nikon it would like to see around 18% of neutral colors. A neutral color is a color which has the same amount of red, green and blue in it. Making it a perfect gray. That is surely not always what you want, but I have to say that quite often this turns out reasonably well.
What to do if you cannot set your white balance in your camera? Can't you edit it if you do not shoot RAW? Sure you can. The reason why it is said that you can easily change white balance in a RAW, but not a JPG is simply: on the JPG, the camera has already applied a white balance correction. Then it saves in JPG, loosing the original sensor data. The resulting file has less information and has less "bandwidth" of altering the white balance, before it starts to look wrong. As we also do not know what the camera applied as white balance correction, we cannot go back to the real state. With RAW, you get that real state and the original sensor data. But you can most certainly still change the white balance of a JPG photo.
The photo in this paragraph actually is the same photo again, but this has a modified white balance to resemble a photo taken during the day. You can clearly see it is warmer than the previous one. The green leaves have lost their blue-ish tint and seem to have a bit more yellow in them. I personally liked this one more than the previous one. But I felt this was still not warm enough and altered it to look like the top one.
Which one would you prefer?