You can set the camera depth of field settings for the camera interest for the chosen camera. The camera depth of field is the amount of space within lens view that maintains focus at given settings, such as camera speed, film speed, lens aperture, and so on. In MotionBuilder, it refers to a method of blurring the view depending on either the camera’s focal point or a specific distance from the camera.
Access the depth of field settings in the Render Options tab of the Cameras Navigator.
Click the Keyframe (K) button to set keyframes on this property. You can modify the Keyframe attribute in the FCurve Editor as well.
Use the Specific Distance slider control to set the distance.
Use the browse field beside Focus Model to locate and select a scene element from the scene browser.
See also Depth of Field Options