Photography is about light. I learned this years ago, when I began to capture images on film. I was careful then to observe the light and of course take notice of the light temperature. Film, darkroom chemicals and paper were expensive. I was on a budget, as I still am today. Technology has now come a long way from using either daylight or tungsten rated film with color correction filters. I have hung onto these and they reside in a small corner of my photo closet, mostly for nostalgic reasons. Technology has made some great advances in photography, but I think people buy the newest camera, because they are looking for technology to save them and in turn, their images. This means they may be losing sight of the skills and practice required to perfect the craft.
As I explain to my students in the “Foundations in Photography” course I teach – the White Balance (WB) controls on your camera help in the removal of unrealistic color casts, so that objects which appear white in person are rendered white in your photo. White balance accounts for the color of light based on an assigned temperature and the extensive algorithms programmed into the modern DSLR. Back in the film days – seems very far in the past, when I refer to it that way – It was achieved by using either daylight or tungsten film in conjunction with a series of filters. For many photographers today, keeping the camera set to Auto White Balance as it came from the manufacturer is the path of least resistance, others will work with the light balance in post processing. Fewer still will actively adjust white balance and fewer from there will venture into the world of custom white balances. It is not always light, however, that affects our white balance, an overabundance of red or blue can skew the camera’s results and create unsightly casts as well. White balance is an evaluative process that each photographer should have a grasp of.
To begin to understand white balance, we must first understand that light has color because light has temperature. Each light source will, therefore, have its own temperature.
Candlelight: 1000 to 2000K
Tungsten (incandescent): 2500 to 3500K
Fluorescent: 4000 to 5000K
Flash: 5000 to 5500K
Daylight: 5000 to 6500K
Cloudy: 6500 to 7500K
Shade: 6000 to 8000K
As you will note – the temperatures are listed with a K for degrees Kelvin, this began long ago in the 1800’s when photography was in its infancy. British physicist William Kelvin heated a block of carbon and observed that it glowed in the heat. As the temperature increased the colors produced changed, showing a range of different colors at different temperatures. The first color started with red light, increasing to a brighter yellow as the temperature went up. Eventually a bright blue-white glow at the highest temperatures. Yes, it may have been simple to start the color scale in Fahrenheit of Centigrade, but the Kelvin scale was chosen as it starts with “absolute zero” (-273 degrees C). That was probably more information than you need to know, but I hope it helps.
You will also note the fact that there is no exact temperature. Take for example, the light bulb in a room at your home, when installed brand new, it could be 3400 or 3500K but by the end of its life it may be only 2800K. The same could be said of sunlight, depending on the season, time of day, weather conditions and so forth. The earth does not orbit the sun in a circle, but rather in an ellipse. The tilt of the earth on its axis also affects the distance and temperature of the light. So as you can see there are numerous variables that affect our cameras.
Further complications come from our computer screens in post processing. Color correction is almost never done on our monitors in the first place, and the type of light can have another effect here as well. Images on our screen are backlit, and in the field we most often have light bathing the subject. Now we are experiencing brightness and contrast differences on top of white balance issues.
The Photoflex 12” White Balancing Tool has solved these problems for me. Setting a custom white balance does most of my color work and the Photoflex 12” White balance disk provides me with the neutral reference needed for accurate color reproduction. I use this disk exclusively as even the colors within our subject can affect how the AUTO white balance setting judges the proper setting selection. Subjects containing an overabundance of blue can falsely indicate the subject is in shade, whereas reds and yellows could indicate incandescent, fluorescent and even candlelight, again influencing the camera’s automatic selection negatively.
In mixed lighting the Photoflex 12” White Balancing Tool is indispensable. Shooting a model against a window allows the daylight to create a portion of the lighting, but incandescent, fluorescent and sometimes flash will be present as well. To complicate this scenario a bit more, the colors of wall finishes also come into play as light reflects the last color it bounced off of. Setting the camera’s white balance in this situation is much easier with the Photoflex 12” White balance disk.
In figure 1, I am photographing the rushing water at McConnell’s Mill State Park in Porterville, Pennsylvania just before Christmas. As you can see, the sky is overcast and I was shooting from a shaded position with additional areas of shade elsewhere in the frame. I was shooting with ISO100 at f32 as this allowed me to maximize depth of field and slow the shutter speed down enough to blur the motion of the water. My shutter speed was about 1.5 seconds for each of the exposures. In the initial exposure I chose the AUTO white balance setting.
In figure 2, I have chosen the CLOUDY white balance setting. In figure 3, I have used SHADE. Both clouds and shade produce a slightly blue light. Shade has the higher color tempurature, so it has a slightly bluer cast to the light. That being said, by selecting the white balance setting for the different types of light, the camera will make adjustments by adding some yellow to make the proper corrections to the color cast. You can see in both images, the varying amount of yellow from the change in white balance.
In figure 4, I have used a CUSTOM white balance. I simply held the Photoflex 12” White Balancing Tool in front of the camera (filling the frame), focused and made a photograph of it. The disk is 18% grey, which is neutral reflectivity, the same 18% grey that is used in your camera’s light meter! I then made the adjustments needed to tell the camera’s computer, which image to use for white balance reference. The image resulted with an accurate representation of the colors present that day.
I opted not to use a white card or white paper purely for accuracy, although I could have done exactly the same process. White paper and white cards can be slightly different in color based on density, paper type and so forth. However, 18% grey (neutral grey) is a standard and has been for years. It does not change.
George Wilson has more than 30 years of experience as a professional photographer, and his work has appeared in many national and international publications. Now focusing on nature and wildlife photography, George exhibits his infrared black and white landscape work and teaches photography at numerous art centers, botanical gardens and at the Walt Disney World Resort in his home state of Florida. A key element to George’s work is his dedication to traditional photography as his post processing is strictly limited to tools aligning with the traditional darkroom. To see more of George's work, visit wilsonphotographyfl.com