As I rewatch The Fellowship of the Ring for perhaps the fiftieth time, I would like to place particular emphasis on this scene.
Notice Gandalf’s face when Saruman describes the Eye of Sauron. He is terrified. Notice his face again when he touches the Palantir and sees the Eye. He recognises it, because he’s seen it before in Dol Goldur.
So Sir Ian McKellan’s reaction as Gandalf to the Eye is fear and recognition. The actor filmed this scene in FotR more than a decade before The Desolation of Smaug, many years before he knew that he would once again don the grey wizard’s hat. Basically, Sir McKellan incorporated a reaction to an event in Gandalf’s history that most film audiences would not recognise or know about. Bravo, sir. I recognise and appreciate your dedication to your craft. If perchance we meet up at a pub, your drinks are on me.
Disclaimer: I do not own the film clip or the image used in this post.