I'm just getting acquainted with cameras and 3d space in Motion 5.
When a camera is selected and one adjusts the "near plane" or "far plane" sliders in the camera table of the inspector,
it is my understanding (from the tutorial I'm taking) that the perspective lines (or grid) should also adjust, thereby showing
me where the cutoff is in the near of far plane. In other words, the lines would go to black at the edge of where the plane is cut off.
However, for me the perspective lines remain there at all times. Indeed, as I adjust the sliders, objects that I have in my 3d space diappear, but at present I have no way of visually seeing where the near or far planes actually start or end.
Unfortunately, you're not missing anything. There is no visual reference for the near plane/far plane sliders. However, the values are displayed in pixels so if you have an object at Z -8000 pixels and a camera at 0 with a far plane of 6000, then you know that object will be invisible until you move the camera Z -2000 pixels.