I thought once too that CameraViewport would just clip the world / camera view or something... I wanted to use it for "widescreen" effect and save some drawing time (top and bottom "border") as well. Then I discovered that it basically just squuezed the view so that the resulting image was... well, squeezed. Now I have black "sprite" borders, stupid way to do "widescreen"... showing less and drawing more. :)