Category Archives: 17. The colour of light

Judging colour temperature 2

Judging colour temperature 2

Introduction

Part 2 of this exercise looks at White Balance (WB). In the glossary of his 2007 book, Exposure, Präkel defines WB as:

“Adjusting for the colour temperature of the illuminating light, so white and neutral colours appear truly neutral and do not show a colour cast”.

The human eye quickly adapts to different light and will perceive things as ‘white’ that it knows to be white. However, digital cameras process light temperature and colour differently. Most digital cameras do this through an inbuilt WB operating system, which allows the camera’s settings to be adjusted to respond to the colour temperature of the light to aid the reproduction of more accurate colours. For example, a cloudy day has a high colour temperature that can emit a bluish colour cast. Opting to use the Cloudy WB preset compensates for this by adding perceived warmth to the image.

The camera I use, a Nikon D5100, has eight preset white balance options, which include Auto WB, Tungsten, Fluorescent, Daylight, Cloudy, Shade and Flash. It also has a Custom WB option, which I have not yet experimented with.

Judging colour temperature 2

This exercise requires that I decide what colour temperature correction a scene may require, if any. The instructions are as follows;

  • Take a similar situation to the last one and shoot the same three kinds of pictures.
  • However, you should vary the camera’s WB settings by taking one at Daylight/Sunlight WB setting, another at the Shade WB setting and the third in Auto WB.
  • Compare the three versions and note differences and preferences of WB settings

I used the same setting as the previous exercise, an area at the front of my building, using three wise monkeys as my subject. I shot at midday in the sun, midday in the shade and late in the afternoon when the sun was close to the horizon.

1. Midday light

Midday, Daylight WB

Midday, Daylight WB

midday, shade WB

Midday, Shade WB

Midday, Auto WB

Midday, Auto WB

Daylight WB has managed quite well with image 1 as gives the image some warmth without bleaching out the shadows. Shade WB has added an orange/yellow colour cast, which looks unnatural. It did, however bring out more of the red tones in the monkeys and make the details in the shadows more prominent. Auto WB has cooled the image by making the paving stones a pale blue/grey and by darkening the shadow areas on the monkeys.

Overall, I think the Daylight WB did a better job of capturing this scene as it did not add any extra coolness or warmth to the image and captured the colours closest to what they actually were.

2. Midday shade

Midday shade, daylight WB

Midday shade, daylight WB

Midday Shade, Shade WB

Midday Shade, Shade WB

Midday shade, AUto WB

Midday shade, AUto WB

I placed the monkeys in the midday shade, and took the three shots adjusting the WB as I went. The daylight WB has not coped as well here as with the first situation and the image has taken on a slight pinkish cast. As shaded areas generally produce cooler looking pictures, the Shade WB has ‘warmed’ up the image with a yellow/orange glow, which is a little bit too warm for my taste. The Auto WB is the version I prefer as it while it has given the grey paving stones a slight bluish colour cast, it does not look unnatural.

3. Sun close to the horizon

Sun near the horizon, Daylight WB

Sun near the horizon, Daylight WB

Sun near the horizon, Shade WB

Sun near the horizon, Shade WB

Sun near the horizon, Auto WB

Sun near the horizon, Auto WB

I took these photographs ½ an hour before the sun was due to set. The Daylight WB has worked well with the orange/yellow low colour temperature light and gives the image perceived warmth. Shade WB has compensated for the blue tones that shaded areas usually hold by adding a strong orange hue to the image. I am undecided as to whether it is too orange or if adds to idea of a setting sun? Auto WB has cooled the feeling of the image and rendered the grey paving stone and the shadows a grey/blue hue. I think a setting somewhere between Daylight WB and Shade WB would be a good WB setting for this scene. I could perhaps achieve this by experimenting with the temperature and tint sliders in the camera RAW processing option in Photoshop Elements 11?

Conclusions

When taking photographs I do adjust the WB settings to match the conditions I am shooting in. However, I now realise that I was doing this routinely with little thought as to how this affects the resulting photographs or how it relates to the lighting conditions. This exercise had also illustrated quite well that lighting conditions can be unpredictable and that other WB settings other that the obvious may actually give more pleasing results. This is something I intend to give more thought to and experiment with in-camera.

Präkel, D. (2007) Basics Photography: Exposure. Lausanne: AVA

http://www.exposureguide.com/white-balance.htm

Judging colour temperature 1

Judging Colour Temperature 1

Introduction

This is the first exercise in the Project: The Colour of Light. The project begins by describing what light is, from a scientific perspective.

Light, like radio waves, x-rays and radar is a type of energy called electromagnetic radiation. Radiation is defined by wavelengths, which vary in length of frequency, from high to low. The majority of the wavelengths on the Electromagnetic Spectrum are invisible to the human eye, such as x-rays (high frequency, short wavelengths) and radio and TV (low-frequency, long wavelengths) (Präkel, 2007, p12).

The light that we can see concerns only a small part of the spectrum. It is seen as the colour of the rainbow. First as a deep red and then as the wavelengths continue to reduce in length, yellow, green, blue and violet can be seen. After violet the radiation becomes invisible as UV light.

This is illustrated in the diagram below.

Our eyes combine the six colours to see ‘white light’. This colourless, ‘white light’ is used to describe standard sunlight in the middle of the day and is measured at a colour temperature of 5500K.

 Colour temperature measures the ‘whiteness’ of light and is measured in kelvin, shown as K. (Präkel, 2007, p20). This scale directly relates to the idea of the colour change seen when heating an object. Thus I found it interesting to note that red would have a lower colour temperature than orange, blue or white. Slightly confusing, as the last chapter in TAoP looked at red and orange as being hot colours and blues as cool. However, it is important to distinguish between colour associations and the measurement of colour temperature.

 Light stops being white and becomes a colour when some part of the spectrum is missing. This happens because the atmospheric particles scatter some of the light wavelengths, particularly at sunrise and sunset. The shorter wavelengths, blue, get scattered more easily and makes the sky appear blue. The longer wavelength colours do not scatter so easily, so remain visible. This, weather permitting, can result in a yellow, orange and red sunset.

Judging colour temperature 1

 Rather unsurprisingly, the temperature of light changes throughout the day. Therefore this exercise asks us to look as these variables when learning to gauge colour temperature. The instructions for the exercise were as follows:

  • Select a subject that can be moved around, that does not have a strong colour.
  • Select a day with clear weather.
  • Take three photographs, one in full sunlight during the middle of the day, one in shade during the middle of the day and one in sunlight when the sun is close to the horizon.
  • Ensure the camera’s WB is set to daylight.
  • Compare the ‘in the shade’ and ‘when the sun is close to the horizon’ photographs with the photograph taken in full sunlight in the middle of the day and make notes.

 I chose a small, off-white Buddha statue I had at home for a subject and selected a position in front of my building. It was a clear, cloudless day and extremely hot. I took three photographs as directed with daylight WB. I opted for RAW format.

1.midday light 85mm, f/5.6, 1/5000, ISO 100

1.midday light
85mm, f/5.6, 1/5000, ISO 100

The first shot was taken at 11:30am when the sun was high and the temperature was 42°C. Full midday sun is described as white or colourless and in this image it has had the effect of bleaching out the statue and surrounding brick work. The colours of the background are pale and uninteresting. The overhead sun has also resulted in highlight spots on the Buddha’s head shoulders and stomach.

65mm, f/5.6, 1/1000, ISO 100
2. midday shade, 65mm, f/5.6, 1/1000, ISO 100

The second photograph was taken at 11:31am with the statue placed in the shade. Shade has a higher colour temperature than ‘white’ day light and contains more blue light. This can be seen in the colour of the stone work and also to a lesser degree on the statue.

50mm, f/5.6, 1/500s, ISO 100

3. Sun close to the horizon, 50mm, f/5.6, 1/500s, ISO 100

The third photograph was taken at 18:04pm, half an hour before sunset. The light has given the image a yellow/orange tone. While the setting sun has a cool colour temperature it, somewhat ironically, appears warmer to look at. Of the three images, this is my favourite as the low side lighting has lit the Buddha well, while casting an interesting shadow which helps to balance out the composition.

Conclusion

This exercise has helped to show that the time of day has a strong effect on the colour of light, which can be seen in both the statue and the surrounding brickwork.

Although I feel as though I need more experience in being able to judge the colour of light reliably, I do feel that reading more about the scientific explanations of what light is and how it behaves has been useful. I knew that early morning and early evening are considered to be the ‘golden’ time for photography but previously didn’t understand it was due to both the temperature of the light as well as the perceived associations with temperature.

This has given me a good foundation to build upon when undertaking the next exercises on Light and the subsequent assignment.

Präkel, D. (2007) Basic Photography: Lighting. Lausanne: AVA

http://www.yorku.ca/eye/spectru.htm