Category Archives: 18 The colour of light

Exercise 29 Judging Colour Temperature 2

EX-29-Comparative

In exercise 29 we are asked to take the same picture in three different intensities of daylight using three different white balance settings. The three types of light were full sun, shade at mid-day and evening and the three white balance settings were daylight, shade and auto.

The picture above shows the results in a comparative grid. The top half are the original photos and the bottom half are blocks of the colour of the “true” white card that is included in each photo.

I have learnt that the “auto” setting on my camera is reasonably accurate in full sun although the white card is a little more grey than it is in the day light setting; in shade it casts a stronger blue tint than the daylight setting as opposed to the warmer cast from the shade setting; in the evening sun the choice is similar, a warm cast from the shade setting or a blue cast from the daylight or auto settings.

I have always tended to leave white balance on auto and to make any necessary adjustments in photoshop so it is helpful to have worked through this exercise and to see that using the shade setting would give a warm tint to portraits taken in the shade or late afternoon.

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Exercise 28 – Judging Colour Temperature 1

The idea behind exercise 28 is to take three photographs of the same subject with the camera’s white balance set to “daylight” in firstly, the mid-day sun, secondly, the mid-day shade and lastly in the evening sun.

Fig. 01 Mid-Day Sun with Daylight White Balance 1/180 at f13, ISO 100

Fig. 01 Mid-Day Sun with Daylight White Balance 1/180 at f13, ISO 100

Fig. 02 Mid-Day Shade with Daylight White Balance 1/20 at f13, ISO 100

Fig. 02 Mid-Day Shade with Daylight White Balance 1/20 at f13, ISO 100

Fig. 03 Evening Sun with Daylight White Balance 1/125 at f5.6, ISO 100

Fig. 03 Evening Sun with Daylight White Balance 1/125 at f5.6, ISO 100

I reshot the evening sun on a different evening as, during the first attempt, there was a build up of cloud that was distorting the results.

The mid-day sun photograph has very crisp whites and the colours are rendered very accurately. The mid-day shade has a distinct blue tint and the evening sun produces a orange/pink tint.

Fig. 04 Comparison of True White

Fig. 04 Comparison of True White

This is best seen by comparing the true white of the “white balance card” as shown in fig. 04.

The explanation for this effect is that, in the middle of the day, 85% of the light that falls on a subject is coming directly from the sun with just 15% coming from the rest of the sky in the form of diffuse sky radiation. Diffuse sky radiation is the term used for solar radiation reaching the earth’s surface after having been scattered from the direct solar beam by molecules or suspensoids in the atmosphere. This light appears blue.

If the subject is in the shade it will only be lit by the sky and any reflected sunlight from, for example, a pavement or a photographic reflector. Because the subject is only lit by the sky it is bathed in blue light as can be seen in fig. 04.

The evening shot in fig. 03 and to the right of fig. 04 was a little surprising, It was taken about an hour before sunset but I was having to wait for gaps in the cloud and I wonder how much this might have impacted the result. I was expecting more of a warm orange glow but the evening light changes so rapidly that minutes before or after might have been quite different. The developing clouds did not give me this luxury. However, it does show that the evening sun provides a warm visual effect.

In reality the evening sun or reddish light is cooler in temperature than the blue light in the shade at mid day.

With film photography these changes in colour temperature and the colour of the light was important to understand. Photographs taken in full shade could have a distinct blue cast which was generally unattractive although photographers complained less about the orange tint provided by the evening sun.

However, I openly admit to using any technology that gives me less to think about. The auto white balance on my camera is excellent and, if it does get it slightly wrong, there are easy ways to address any problems in photoshop.

1990 Village Children Boracay

Fig. 05 1990 Village Children Boracay

The above image taken on 35mm slide film in 1990 shows the effect of “golden hour” light in the tropics.

Sources

Books

Freeman, Michael. (2013) Capturing Light: The Heart of Photography. Lewes: The Ilex Press Limited.