An interesting form of lighting. To create synthetic light, take a white light source, such as a halogen lamp, and place a rapidly rotating color filter disc in front of it.

Choose the filters so that their sum is neutral gray.

If the filter disc rotates fast enough (for example, beyond 100 rotations per second), viewers will not perceive any flicker. Stationary objects in the scene will appear to be lit by a steady white light. On the other hand, moving objects will appear to rapidly change color. Things like rotating patterns and vibrating strings will exhibit stripes of colors, depending on the relation between their rate of rotation (or frequency), and the rate of rotation of the filter disc.

I apologize for including links to pictures, but this is something that really needs to be seen. I wish my powers of ekphrasis were stronger.

For interesting examples, take a look at

  • The rounded forms are white plastic discs in rapid rotation. Notice that the shadows too have a color...
  • A vibrating strings analyzes the synthetic light in its constituents.

I shot those pictures at Piero Fogliati: poeta della luce, a fascinating exhibition recently held in Torino ( Contrast this idea with the Harris shutter.