There is a camera distortion that takes place with the FOV, etc. I believe this is intentional and there are some workarounds. 1. Ditch the box idea and simply make surface walls ceiling, floor etc, then whatever wall is behind the camera, get rid of that, move the camera back, and zoom in a bit so you don't see the edges. You'll have to turn your sky off or play a whole lot. If you have windows with a sky backround showing through in the room, this won't work, only on a closed room with no windows. Use light objects to light the room. 2. If you're going to stay with the box idea, then elongate one end, make your room double or triple in length and put all your stuff at one end, the camera at the other. Zoom the camera a bit. 3. Make a really huge room (which has the overall effect of making the camera smaller). You can position the camera any where you want and the distortion tends to go away. You'll have to turn off the fog and haze because that will start to show inside the room. (which means your sky showing in a window is not all that exciting). You'll also have to really enlarge the lights and turn up the intensity. You will also loose some detail on the far wall, but keep tweaking it. Hope that helps.