Each camera keyframe will record the camera's location in world and its rotation about a pivot at that particular location, not the apparent pivot of when you were manipulating the view. You will not have recorded a circular camera path. The path will be straight lines between keyframes.
If you really want to make life hell and do the animation in Photoshop, then record a keyframe at each 5 to 10 degrees of rotation of the camera while you manipulate the view. That'll create a polygonal path that quite closely approximates a circle.
You could be tempted to keep the camera stationary and rotate Scene instead but the lights are outside of Scene so they would need to be rotated individually in order to create the illusion of only the camera moving.
I get it! Thanks very much! Once again, your insights helped me wrap my head around a tough Photoshop question.
I agree that animating the camera in Photoshop is indeed hell, but what is the alternative?
I've tried importing 3DS and Collada files and the camera animation is ignored.
I can import an object animation, but then the background IBL doesn't rotate.
FEATURE REQUEST: It would also be useful if you could save the camera animation, and use it as a preset.
Any advice most gratefully recieved :O)