To vorticey:
> teetering head, no, the camera must be moved with the spinning axes therefore the light would be a circle still. <
The camera is rigidly attached to the fuselage and is located directly below the mast. It is therefor on the mast axis (i.e. 'rotor hub plane'). The tip lights are on the circumference of the 'tip path plane'. When the 'tip path plane' tilts in respect to the 'rotor hub plane' the circle will appear as an ellipse. To take this to a ludicrous extreme, if the disk was tilted 90-degrees then the camera would see a straight line. (i.e. the edge of the disk.)
This 'narrowing' of the circle can be equated, in a cyclical context, with a reduction in the diameter of the circle due to increased coning.
I think.