Saturday, 12 June 2010

Digital Photographic Practice: Exercise 10 (ii): Colour Cast and White Balance

Mixed Incandescent and Natural Light
The following shots were taken in my back garden about an hour before sunset on a completely overcast evening. The focal length was 50mm and the exposure between 1/8 and 1/10, f/8 and ISO400 with image stabilisation on.
The wallpaper in the dining room is a relatively strong yellow, but has taken on a distinct orange tone in all but the ‘tungsten’ lighting setting, which is the most accurate for the interior – see also the colour of the paper on the music stand in the background.  However, the dining chairs, by comparison have taken on a blue tone in the ‘tungsten’ setting as they are receiving considerable light from the patio windows.
The ‘auto’ setting has clearly biased itself towards the exterior lighting conditions, producing a neutral colour to the grey render and the strongest orange in the interior, while the ‘sunny’ white balance tones down the orange, but has produced a rather un-natural blue tone to the render.
The frame labelled ‘personal choice’ is actually balanced with the ‘cloudy’ setting. This has produced a more accurate colour on the wall than ‘sunny’ – although slightly bluer than ‘auto’. However the orange of the interior is less pronounced, and the green of the vegetation is a little ‘fresher’. To me this is the best balance that can be achieved in this image without resorting to blending images. It manages to convey the contrast between a rather cold and dreary evening and the relative warmth of the dining room without appearing too artificial.
General tinkering with the sliders produced no overall improvements in the final image to my eye.
In mixed lighting there is no technically correct answer because correctness depends on which light source you consider as the primary one. The others are then, inevitably, less accurately portrayed. So, even more than in the single lighting case the choice of white balance in mixed lighting is down to the desired artistic effect.

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