It seems like Vue only keeps the focal length horizontally - whereas when you actually hold a camera and rotate it to go vertical, the subject will never chage size. It's the same POV angle of degrees regardless of rotation. In the real world, it doesn't matter the size of your negative or CCD, and in a 3D program it doesn't matter what size your render will eventually be (800 pixels wide, or 2,000 pixels - it doesn't matter when you're just setting up the camera), it's an angle measurement in degrees from a starting point - the lens itself. It's a spherical projection onto a focal plane - so it doesn't matter if it's vertical or horizontal, or any angle in between. In Vue, it looks as if you will only maintain your horizontal angle degree POV (best example being the Viking ship example above by Yggdrasil) while adding more or less on the top or bottom depending on your chosen aspect ratio. Not necessarily a bug - maybe it was just a bit too much for the programmers to figure out in a real-world way, so they chose to stick to horizontal measurements (which might be logical as it's main use seems to still be landscapes)?