Judging colour temperature 1

For this exercise, I took a number of photographs of a light coloured stone statue on a day with sunny intervals at the beginning of September.

Image 1: Direct sunlight - lunchtime

Nikon 18-70mm at 70mm: Iso 400 f4.5 for 1/1250th (Daylight white balance)

I first placed the statue in a sunlit position with dark undergrowth in the background.

Image 2: Shady position - lunchtime

Nikon 18-70mm at 70mm: Iso 400 f4.5 for 1/80th second (daylight white balance)

I moved the statue a short distance into a shaded position. The exposure level dropped by 4 stops, so that the dark leaves in the background became visible.

Image 3: Sunny position - evening sun

Nikon 18-70mm at 52mm: Iso 800 f4.5 for 1/40th second (daylight white balance)

This photograph was taken at 6.30 pm in a patch of evening sunlight (sunset was about 7.15 pm) on the same day. The exposure level dropped by another two stops compared to image 2, which would mean the shutter speed would reduce to about 1/20th second. Even though I was using a tripod, I chose to increase the sensitivity to Iso 800 resulting in a shutter speed twice as long at 1/40th second.

In each case, I compared the colours of the statue in front of me with the corresponding image on the camera's screen.

Observations

In each case, my perception was that the statue was a slightly richer colour than captured by the camera, including the photographs taken in the evening light.

I noted this tendency to understate the colour intensity in the first few months of using the Nikon D200. I was living for two months in Bali where there is tropical sunlight and many bright colours. As a result, at that time, I adjusted the camera's "Optimize image" setting to Vivid, instead of the normal setting. This made the colours shown on the screen closer to my perception when I took the photographs. After some time back in UK, I changed the setting back to the normal position. This was partly because the UK is a less colourful place, but also because I found that the colours could be restored when processing the image, by adjusting the white balance in Lightroom.

Comparing the colours in the three pictures side by side, the light from the mid-day sun in image 1 is the most neutral and colourless. The stone is an unsaturated orange colour, beige being the dominant tone mixed with grey-green elements.

In image 3, the evening sunlight adds to the saturation of the orange tones, and the stone becomes a reasonably bright orange.

In image 2, the orange areas of the stone lose some saturation to become a creamy white. The grey-green areas of stone become a more blue-grey colour.

In image 2, the statue was in a narrow garden between a red-brick two story building and some large sycamore trees and undergrowth. As a result, the blue of the sky made up a relatively small portion of the direct light on the statue. Nevertheless, the change in colours by moving into the shade appears to be consistent with an increase in blue cool colours. I could make out no obvious signs of red from the brickwork or green from the undergrowth.

Conclusion

Doing this exercise has prompted me to check more regularly whether the colours portrayed on the camera's screen represent reasonably the actual colours of he scene. In recent years, I have tended to leave the White Balance on Automatic and adjusted the white balance at a much later date when processing the photographs. Whilst this seems to be fairly common practice, I can understand that this is likely to result in an image that is visually attractive, but not necessarily close to the reality of the subject.