Rods, Cones and Perception
Landscape photographers are especially well acquainted with the beautiful colours of the ‘golden-hour’ surrounding both sunrise and sunset; the subdued light intensity and twilight hues facilitate easy visualisation of our intended final image. However, when the light fades further towards darkness, it becomes increasingly difficult to ‘see’ such compelling results. The falling light levels require seemingly impossible degrees of visualisation as we try to mentally correct the ‘exposure’ to an acceptable level compared to the darkness that surrounds us. When the twilight colours have faded, scenes shift towards a more subdued monochromatic palette, the drama disappears. It is hardly surprising therefore, that once the colours ‘fade’, most of us stop shooting.
As light levels fall, our human colour perception changes; we become less able to discern colours. As night approaches, our perception moves towards black and white as the light-sensitive rods in the retina gradually take over from the colour sensitive cones. Such change occurs gradually, and during the transition, there is also a shift in perceived luminance towards a more monochromatic blue. The phenomenon, known as the Purkinje effect, causes green, blue and violet colours to appear brighter, and red, orange and yellow colours, to look darker. So, as twilight fades, we start to perceive colour inaccurately and we become much less aware of the of the colour still available to our camera sensor.
I’m enormously fond of this very special and romantic location in the Lake District. I do love photographing jetties. Perhaps this is because they signify the start of a new voyage, a subliminal suggestion of moving on, hope for better things to come. Perhaps they evoke our primitive exploratory instincts and inquisitive wonderings about different lands that exist beyond the horizon.
Just ten minutes after a less than memorable sunset, the twilight hues had faded and I was ready to leave; but I have learned from experience that it often pays to continue shooting for a while after the colours have disappeared. I used neutral density filtration to enable a long exposure to completely ‘calm’ the lake and in post-processing, I ‘seasoned’ the image with a harmonious palette, creating a mood of peace and tranquillity.
The realisation that opportunity lingers as twilight gives way to night can bring enormous rewards.