Bingowings said:
The lens could do with adjustment. It looks too dark to sit the rest of the head, I'd try lowering the contrast on the whole area a little and see if that helps.
It will be a real bugger replacing every shot with Artoo's lens in shot (best of luck).
That I think is the only time in the saga you can clearly see that they replaced his normal lens with some sort of light defuser (paper or gauze) to make it glow right.
No need to replace any other shot
J