A physiogram is a long exposure photograph of moving light.

In this workshop we'll explore and create these pictures of light in motion...

There are many ways to make the light move. You can hang the light on a swinging pendulum you can put the light on a machine that moves the light or you can even swing the camera to make it look like the light is moving. However you move the light...

the resulting image is a record of the path the light took during its journey.

The mathematical term for these images are hyptotrochoid patterns. They are the same patterns that you get when playing with spirographs.