More complex methods allow the manipulation of the computer graphics model including view up vector, clipping planes, and camera perspective. These are positive distances along the direction of projection. How these values are set can have a large impact on how well z-buffering works. In particular the front clipping plane can make a very big difference. Setting it to 0.01 when it really could be 1.0 can have a big impact on your z-buffer resolution farther away.
Larger values yield greater perspective distortion.
This is used when generating stereo images. Set the size of the cameras lens in world coordinates. This is only used when the renderer is doing focal depth rendering. When that is being done the size of the focal disk will effect how significant the depth effects will be. This determines if the camera should do a perspective or parallel projection.