by John H Siskin
I teach several classes about lighting, so I wanted to take a few words to try to help everybody understand some of the basic things about the color of light. A digital camera can compensate for many different light types but most cameras have trouble when you mix light colors. For instance if you shoot an office that is lit with fluorescent tubes and someone has a desk lamp with a tungsten bulb the shot will not look natural to the eye. The human eye is always interpreting the information it collects because it is connected to the brain. Consequently the eye can fix the color in an office, but unfortunately won’t fix the colors in a print.
My favorite light source is strobe. I would rather use the strobe than daylight because I have much more control. Not only can I control the power of the strobe I can manipulate the character of the light. A professional strobe actually has very few controls. Strobe power output, model light output, on/off for the model light, on off for the internal slave and power, and not every strobe has all of these. The most important control is strobe power output; on some strobes this is the only control! Not only is it the most important control; strobe power is the most important factor in what strobe to buy.
One of the biggest reasons that I think power is so important is that I diffuse the light from the strobe in order to make the strobe act as a large light source. This enables me to create smooth light with diffused highlights that has a smooth long transition into shadow.
Strobe light is created when a spark jumps through a tube of Xenon gas. This is the reason that the light has such a short duration, about 1/1000th of a second, but sometimes as shot as 1/50000th of a second. This means that you do not need to use a tripod to shoot people with strobes, even if you are a little shaky. Another wonderful characteristic of strobe is that they are the same color as average daylight. This makes it easy to use strobes to fill in a daylight image or to match an indoor shot to the window light.
Both Strobes and daylight and tungsten bulb have a continuous spectrum. This means that if you put the light from any of these sources through a prism to create a rainbow there are not black areas where the light drops out. Many other man made lights have this problem. This can cause colors to reproduce inaccurately even when the light looks useable.
Daylight has the tremendous advantage of being readily available and free. It is easy to see daylight; you don’t need to previsualize it as you do with strobes. Day light is hard to control, it often take 12 hours to move the light source to the other side of the set. But iif you are in the right place at the right time daylight is awesome. I really like mixing daylight with strobe out doors to create a softer light that still sparkles. Flash fill is a wonderful way to take pictures.
Tungsten lights, first a definition, tungsten lights have a filament and the filament is inside a bulb; the light bulbs in your house are tungsten lights. When these bulbs were made specifically for still and movie use they were made to run at very high temperatures so there would be more blue in the light and so the light would be brighter.
If you make a light to run that hot in a regular style bulb it will start to change color in just a few hours and fail very quickly. There are household style bulbs available for photography. They fit in fixtures by Smith-Victor and other companies. These are very inexpensive and they can be good tools for learning how light works, but since they do not have stable color they are not great for professional usage because their color shifts.
Then, there are also quartz bulbs, which are more useful!
I had such a wonderful time with these when I shot film. These bulbs have stable color for as much as 60 hours. Because you could run exposures of more than a minute with film and you didn’t have to light the whole shot at the same time there were many creative things you could do. I am attaching a shot I took with two quartz lights and a Kodak slide projector.
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