Entries Tagged 'fundamentals' ↓

The actual answer depends on what mood you are trying to set in the picture you are taking.

When a photographer uses the term ‘hard’ to describe the light they are usually referring to light from a single small source. Bright sunlight at midday is hard for example, as is light from a single spot light or flash.Hard light generally makes for very dark or black shadows, a high contrast, and intense colours in any scene.

Soft light on the other hand is light which is more diffused. There is less contrast, and the reduction in areas of intense dark shadow allows more detail to appear.

Putting some tissue or tracing paper between a hard light source and the subject will result in diffusing/softening of the light. Equally good is bouncing light from surfaces, such as reflectors or walls. This is fine indoors with spot lights or flash; but outdoors it’s a little trickier. Depending on the subject, sometimes the only option available is to wait for some cloud.

Getting yourself familiar with the differences between hard and soft light and the way it effects the mood of the subject is a good idea, since it can have a radical effect on the final image.

We know from experience that the colour of light is not always the same; Daylight varies depending on the time of the day or the year. Artificial sources also vary in the light they produce.

It is this variation in hue (or pure colour) which is referred to as the colour temperature of the light. A low colour temperature makes for a warmer red or yellow light while a high colour temperature implies a colder blue light.

The colour temperature of light is expressed using the Kelvin scale; where zero is the coldest you can get or absolute zero. (Actually about -273 degrees Celsius.) The table below outlines the colour temperature under various lighting conditions; from extreme bright to candlelight.

If a true representation of colour is required filters can be used to dampen the effects of colour cast. For very warm temperatures orange filters can be used moving to blue filters for colder temperatures. In around the middle ranges (approximately 5500-5000 K) filtering is not required to achieve accurate colour.

In a film camera different types of film can also be used depending on whether the shooting conditions are to be under tungsten filament lighting or in natural light.
These techniques all have the effect of shifting the colour temperature of the light entering the camera.

When using a digital camera, we can achieve the same result by using the white balance function to achieve this shift of colour temperature.

What is White Balance ?

We now know that the light our eyes perceive to be ‘white’ is rarely actually white. It has a colour cast associated with it based on it’s temperature.
Usually modern digital cameras have pre-set settings for bright daylight, cloud, tungsten and fluorescent lighting. These settings act to shift the colour cast based on the expected temperature of the surrounding light.

Compare the two images below; Both were taken under tungsten filament light. The first one was taken using a normal daylight white balance (WB) setting on the camera. We can clearly see the yellow/red light in the image, which completely muddies the blue ball. In the second image, the WB was set to tungsten; here, the blue colour of the ball is accurately reproduced.

1. Daylight White Balance: Image appears with a red/yellow cast.	2. Tungsten White Balance: Accurate colour reproduction in the resulting image. Notice in particular the accurate blue of the ball.

Many cameras also have the ability to custom set the white balance, this is normally done by pointing the camera at a white object and giving the camera the information that we expect this to be white. The camera then performs a calculation based on the sensor cast colour it receives for the white object, and shifts the white balance accordingly. Cards with exact white and grey scales printed on them are available, and can be used for this purpose.

So, why should a photographer know this stuff?

Have you ever taken a photograph taken indoors under artificial light, and seen it produce a red/orange cast? Well, at least now, we know the reason why this happens.

If you require the accurate reproduction of a subjects colour, it is important to be aware of how light is behaving, and also the steps that can be taken to eliminate any undesired effects. It is also useful to know, since many image applications, such as Photoshop and iPhoto, use the terminology.

There is, however, one thing to bare in mind though; these varying colour casts may actually greatly improve the quality of your final image.

The low Kelvin temperatures can lend amazing warmth and atmosphere to shots. (I know, low temperature warmth sounds a little odd, but that’s the scale!). The warm red light of a sunset, particularly in Autumn or Winter, or the yellow/orange cast of tungsten or candlelight can greatly enhance many images. Similarly, the cool blues of high temperature colour can also be used to dramatic effect.