Exercise 10: Colour Cast and White Balance

One of my early memories from when I first became interested in photography and was experimenting with my first film SLR was being shocked by the extreme colour cast from a some pictures I took under tungsten lighting. The abiding thing this experience taught me was to be wary of how our eyes can compensate for different lighting situations and how the camera will not do this. Since the advent of digital photography however, white/colour balance has become less of an issue, especially if photographs are shot in RAW as the colour balance can be altered post capture. (I wonder however if this causes any problems - for example, is there a degradation in quality doing this versus setting white balance at the time of capture.)

As I always shoot in RAW mode I only ever have my camera set to automatic white balance. I find this gives a neutral result most of the time, however, I always experiment with white balance as this can significantly alter the mood of a photograph - higher colour temperatures giving a cooler/bluer result and lower settings giving a warmer/red/orange effect. White balance can also significantly effect colour saturation in an image and perception of exposure.

I skipped the first part of this exercise which called for photographs to be taken using different white balance settings in sunny, cloudy and shady situations as this is something I am familiar with already as described above. The second part of the project interested me however as this called for photographs to be taken in mixed lighting situations. The pictures I have chosen are taken outside my house at dusk with a streetlamp in shot. The different colour temperatures of the sky and the lamp give interesting results

All of these images were shot in RAW format and the Kelvin reading here is taken from Lightroom without any processing, interestingly the amount indicated was different to the one my camera manual gave.

Automatic White Balance:

7350 Kelvin (-23 tint)

Firstly I wanted to compare how my camera rendered the scene with the automatic white balance setting. This is pretty close to how I remember the scene looking with the sky being grey/blue and the orange of the streetlamp illuminating the scene. The streetlamp itself is rendered white.

Incandescent:

2950 Kelvin (-3 tint)

This setting has given the light source the appearance of white light, the orange cast from the street lamp is virtually eliminated and the sky is a dramatic, saturated blue. The centre of the light appears pure white as does the 'halo' around it. This also makes the light and the sky contrast more and the light appears to be brighter while the fence and grass appears much darker.

Fluorescent:

3950 Kelvin (+30 tint)

A much redder element is added here although the blue of the sky is maintained. The light has a more pink than orange tint.

Daylight:

5000K (-6 tint)

This image appears much brighter than the previous 2, the sky is much more muted and grey rather than blue. The cast from the lamp has a warm orange feel.

Cloudy:

5700K (-8 tint)

Very similar to the daylight setting, the main difference is an apparent increase in brightness.

Flash:

6100K (-6 tint)

There is a slight difference in the perceived brightness here in the sky and grass. The grass appears slightly less orange and more green.