An Alternative is to select the imported camera and, while selected, use the Add Animation Clip to the camera; this leaves the camera itself without keyframes but animated. Now convert it. If only PSR were animated, you could write the keyframes back. Some enjoy the copy-and-paste dance, but I love to have them safe in a clip. This included the Field Of View, which can be part of the Animation Clip and be written back with no loss in my experience.