I've seen it in other programs. I wouldn't be suprised if your camera is cutting off because of the camera's "size". Can one scale the camera size in carrara? I know that this is possible in Bryce. (I havent tried working with the camera and lights yet in Carrara, and after a respit od a couple months I'm still trying to get a handle on the basics). Otherwise you may try rescaling your 'tunnel' larger so that the camera 'fits' better.