31. Mixing natural and artificial light
Occasionally, you will have to shoot in a place where you have both artificial and natural light. You may have sunlight coming through a window and light coming from a lamp on a table.
The best way to handle this is to white balance the camera in the mixed light. Place your white card next to the subject you will be filming, and press auto-white balance. After the camera is white balanced, turn white balance back to manual so it doesn’t re-balance.
Another way to handle this situation would be to place a “gel” over the window, changing the light coming through the window to “match” the tungsten lamp. A gel is a thin sheet of colored polycarbonate or polyester that is used to add a minor tint to light.
As a practical matter, you will probably only use three colors, one each to match each the three white balance presets of your camcorder: tungsten, outside, and fluorescent.
The type of gel that you will be using is a “color correction” gel. You may see them referred to as CTB (Color Temperature Blue) and CTO (Color Temperature Orange.)
Two other gels you should know about are ND and diffusion gels.
- ND gels reduce the amount of light falling on a scene, without changing its color.
- ND gels usually come in gray colored sheets. The higher the ND number, the darker the gray.
- Diffusion gels soften the light falling on a scene, without changing its color.
- Diffusion gels usually come in translucent white sheets.
Manufacturers, like Rosco, sell inexpensive swatch books containing samples of different gels.
Next month: Getting good sound
Copyright Tony Levelle, 2009
