1) I tweaked the focal length and saw that the Field of View is changing (inversely) which makes intuitive sense. But I also notice that the FOV is changing when I am changing Sensor size - how is that possible? FOV should be fixed for a fixed focal length, right?
2) Is the Sensor size related to cx, cy - principal point in the Pin Hole Camera model? Ref
3) The camera parameters I have are of this format: