Introduction to White Balance

White Balance is an aspect of photography that many digital camera owners don’t understand or use – but it’s something well worth learning about as it can have a real impact upon the shots you take.

So for those of you who have been avoiding White Balance – let me introduce you to it. I promise to keep it as simple as possible and keep what follows as useable as I can:

At its simplest – the reason we adjust white balance is to get the colors in your images as accurate as possible.

Why would you need to get the color right in your shots?

You might have noticed when examining shots after taking them that at times images can come out with an orange, blue, yellow etc look to them – despite the fact that to the naked eye the scene looked quite normal. The reason for this is that images different sources of light have a different ‘color’ (or temperature) to them. Fluorescent lighting adds a bluish cast to photos whereas tungsten (incandescent/bulbs) lights add a yellowish tinge to photos.

The range in different temperatures ranges from the very cool light of blue sky through to the very warm light of a candle.

We don’t generally notice this difference in temperature because our eyes adjust automatically for it. So unless the temperature of the light is very extreme a white sheet of paper will generally look white to us. However a digital camera doesn’t have the smarts to make these adjustments automatically and sometimes will need us to tell it how to treat different light.


So for cooler (blue or green) light you’ll tell the camera to warm things up and in warm light you’ll tell it to cool down.

Adjusting White Balance

Different digital cameras have different ways of adjusting white balance so ultimately you’ll need to get out your camera’s manual out to work out the specifics of how to make changes. Having said this – many digital cameras have automatic and semi-automatic modes to help you make the adjustments.

Preset White Balance Settings

Here are some of the basic White Balance settings you’ll find on cameras:

* Auto – this is where the camera makes a best guess on a shot by shot basis. You’ll find it works in many situations but it’s worth venturing out of it for trickier lighting.
* Tungsten – this mode is usually symbolized with a little bulb and is for shooting indoors, especially under tungsten (incandescent) lighting (such as bulb lighting). It generally cools down the colors in photos.
* Fluorescent – this compensates for the ‘cool’ light of fluorescent light and will warm up your shots.
* Daylight/Sunny – not all cameras have this setting because it sets things as fairly ‘normal’ white balance settings.
* Cloudy – this setting generally warms things up a touch more than ‘daylight’ mode.
* Flash – the flash of a camera can be quite a cool light so in Flash WB mode you’ll find it warms up your shots a touch.
* Shade – the light in shade is generally cooler (bluer) than shooting in direct sunlight so this mode will warm things up a little.

Manual White Balance Adjustments

In most cases you can get a pretty accurate result using the above preset white balance modes – but some digital cameras (most DSLRs and higher end point and shoots) allow for manual white balance adjustments also.

The way this is used varies a little between models but in essence what you do is to tell your camera what white looks like in a shot so that it has something as a reference point for deciding how other colors should look. You can do this by buying yourself a white (or grey) card which is specifically designed for this task – or you can find some other appropriately colored object around you to do the job.

Learning about Exposure – The Exposure Triangle

The three main elements that need to be considered when playing around with exposure by calling them ‘the exposure triangle’.

Each of the three aspects of the triangle relate to light and how it enters and interacts with the camera.
The three elements are:

1. written a post on ISO – the measure of a digital camera sensor’s sensitivity to light
2. Aperture – the size of the opening in the lens when a picture is taken
3. Shutter Speed – the amount of time that the shutter is open

It is at the intersection of these three elements that an image’s exposure is worked out.

Most importantly – a change in one of the elements will impact the others. This means that you can never really isolate just one of the elements alone but always need to have the others in the back of your mind.
3 Metaphors for understanding the digital photography exposure triangle:

Many people describe the relationship between ISO, Aperture and Shutter Speed using different metaphors to help us get our heads around it. Let me share three. A quick word of warning first though – like most metaphors – these are far from perfect and are just for illustrative purposes:

The Window

Imagine your camera is like a window with shutters that open and close.

Aperture is the size of the window. If it’s bigger more light gets through and the room is brighter.

Shutter Speed is the amount of time that the shutters of the window are open. The longer you leave them open the more that comes in.

Now imagine that you’re inside the room and are wearing sunglasses (hopefully this isn’t too much of a stretch). Your eyes become desensitized to the light that comes in (it’s like a low ISO).

There are a number of ways of increasing the amount of light in the room (or at least how much it seems that there is. You could increase the time that the shutters are open (decrease shutter speed), you could increase the size of the window (increase aperture) or you could take off your sunglasses (make the ISO larger).

Ok – it’s not the perfect illustration – but you get the idea.

Sunbaking

Another way that a friend recently shared with me is to think about digital camera exposure as being like getting a sun tan.

Now getting a suntan is something I always wanted growing up – but unfortunately being very fair skinned it was something that I never really achieved. All I did was get burnt when I went out into the sun. In a sense your skin type is like an ISO rating. Some people are more sensitive to the sun than others.

Shutter speed in this metaphor is like the length of time you spend out in the sun. The longer you spend in the sun the increased chances of you getting a tan (of course spending too long in the sun can mean being over exposed).

Aperture is like sunscreen which you apply to your skin. Sunscreen blocks the sun at different rates depending upon it’s strength. Apply a high strength sunscreen and you decrease the amount of sunlight that gets through – and as a result even a person with highly sensitive skin can spend more time in the sun (ie decrease the Aperture and you can slow down shutter speed and/or decrease ISO).

As I’ve said – neither metaphor is perfect but both illustrate the interconnectedness of shutter speed, aperture and ISO on your digital camera.

Note:(the width of the hose is aperture, the length that the hose is left on is shutter speed and the pressure of the water (the speed it gets through) is ISO.