The circle of confusion is the two-dimensional blur created when light rays from a point source do not converge perfectly on the focal plane. In optics and projection, it defines the acceptable limit of sharpness; as long as this blur spot is smaller than the resolution limit of the human eye or camera sensor, the image or projected pattern appears in focus.
Heard on the job
If you push the followspot that far out of focus, the circle of confusion gets so large it washes out the entire set piece.
Also heard as
- blur circle