The assignment for the week of 4 - 10 January 2010 is the "Color of Light." Because the auto white balance functions in our cameras have become so good at “correcting” the color cast of various light sources, it has become less obvious to most photographers that the “color of light” varies based on the light source. Different light sources emit light at different color “temperatures” (we define the color of light in degrees Kelvin) and reflection of this light off a subject will affect our perception of that subject.
We perceive light lower on the Kelvin scale as “warm,” tending toward yellow or red. Sunlight at sunrise and sunset has a “warm” tone, as does the light from incandescent light bulbs. If we were to take a picture of a white object under this warm light without correcting for white balance, it would look yellow, and all the other objects in the scene would have a yellow color cast as well. We generally perceive warm light as "comfortable" or inviting, and describe objects viewed in this light as possessing a warm glow.
We perceive light that is higher on the Kelvin scale as “cool” light tending toward blue. Since the blue sky is the primary source of light in open shade, objects photographed in this light will take on a blue color cast. We don’t normally perceive this blue cast in real life, because our brains do such a wonderful job of automatically correcting the colors based on a “reference color.” In other words, we know subconsciously what specific objects should look like, and our brains will automatically correct for the color cast from different light sources so that we perceived the colors of surrounding objects correctly. This is probably an evolved trait, since being able to properly discern the color of specific foods would provide an evolutionary advantage.
Pre-dawn or twilight light is also "cool" light, and our mood is effected by the association of this "cool" light with cooler, less comfortable or less inviting circumstances. Portraits taken under cool lighting are often perceived as more aloof and less inviting than those taken under warmer light.
So, we can see that the “color of light” is important in defining the scene, and can help impart a specific mood or feeling to an image. Unfortunately, we often get lazy, and let “auto white balance” automatically correct the color cast of various scenes so that the whites are rendered as color-neutral, with no color cast caused by the light source. This can have a negative impact on our attempts to portray a scene, and can weaken a mood or feeling that would have been enhanced if we would have left the color cast in the scene. Obviously a sunset image where all the colors are “corrected” towards more neutral colors would look much less impressive than in real life.
The purpose of this week’s exercise is to encourage you to pay attention to the “color of light” and to use this color to enhance the mood or feeling of your composition. I would recommend that you turn off auto white balance on your camera, and use the “daylight” white balance setting as a starting point to capture an accurate representation of the scene, color cast and all. (“Daylight” white balance is usually the closest to providing a “neutral” white balance setting that will faithfully reproduce the “real” colors in the scene, without correction for the color cast from light sources.)
The assignment for the week of 4 - 10 January 2010 is the "Color of Light." Please upload your images to the "Color of Light” album in the Weekly Assignments category of the Gallery no-later-than midnight Mountain Time (GMT -07:00) on Sunday, 10 January 2010.
I will look forward to seeing your images.
Keith
