You can modify a camera’s depth of field parameters in the Camera Inspector:
DOF Blur Amount: A slider to control the maximum amount of blur applied to out-of-focus objects.
Focus Offset: A slider to set the distance from the camera where objects are in perfect focus.
Near Focus: A slider to set the nearest point of focus, measured in pixels as an offset from the focal distance.
Far Focus: A slider to set the farthest point of focus, measured in pixels as an offset from the focal distance.
Infinite Focus: A checkbox that sets the far focus to infinity, overriding the setting chosen in the Far Focus slider.
Filter: A pop-up menu to set the type of blur algorithm used to render the out-of-focus areas. Choices include Gaussian or Defocus. The Defocus setting renders a more realistic effect, but may impact performance.
Tip: For best results, use Gaussian when setting up a scene, and Defocus for final output.
Filter Shape: When the Filter pop-up menu is set to Defocus, this pop-up menu lets you choose between a disk-shaped, or polygon-shaped render kernel. Different shapes produce subtly different blur patterns simulating different types of camera lenses.
Sides: When the Filter Shape pop-up menu is set to Polygon, this slider sets the number of sides in the polygon.
Depth: A pop-up menu to set the depth to Radial or Planar. Although Radial typically exhibits more realistic results, there are some cases where it may look artificial. These include cases where the camera is set to a high DOF Blur Amount, or if the image layer is close to the edge of the frame, is very large, is rotated, and so on. In these cases, switching to Planar may improve results.