Adobe AFTER EFFECTS CS3 PROFESSIONAL User Manual page 374

Original (top left), with effect applied (bottom left), and with effect applied and Invert Alpha selected (bottom right)
The z axis value at which to slice the image. Everything with a depth value less than this Depth value is matted out.
Depth
To determine the depth of an object, click it in the Composition panel or Layer panel using the Selection tool while
the effect is selected.
The amount of feather along the matte's edges.
Feather
Select to matte out everything with a depth greater than the Depth value. Deselect to matte out everything
Invert
with a depth less than the Depth value.
See also
"About 3D layers" on page 174
Depth Of Field effect
The Depth Of Field effect simulates a camera that's focusing at one depth (focal plane) in a 3D scene, blurring objects
at other depths. This effect uses the depth information from the auxiliary channel of an imported file representing a
3D scene. To use the depth information that After Effects calculates for a camera layer, see "Create a camera layer
and change camera settings" on page 179.
This effect works with 8-bpc color.
Original (top left), and with Depth Of Field applied using different Focal Plane values (bottom left and bottom right)
The distance along the z axis of the focal plane from the camera.
Focal Plane
AFTER EFFECTS CS3 368
User Guide