The Camera's nearClip and farClip properties are documented to use eye coordinate system. This eye system should be specified, especially because it has inconsistent definitions for different cameras. From the current behavior it seems that:

For the default camera, the distance "1" means distance of the camera and the projection plane (so it usually is hunderds of scene units).

For "fixed eye" the distance 1 always means 1 scene unit (regardless of the position of the projection plane).