Sir Ian McKellen wept at the end of his first day on the set of the new The Hobbit movie after shooting a scene involving hi-tech special effects.

The veteran actor reprises his role as Gandalf in the upcoming third and final installment, The Hobbit: The Battle of the Five Armies, and producers used a 'green screen' technique to simulate the background in some scenes.

It involves the actors working on a blank stage so that tech crew members can later insert images of those surrounding them, but the sterile nature of the method left the proud actor in despair.

He tells U.K. talk show host Graham Norton, "Some of it was really exciting like filming on a mountain top. But filming with a green screen is the miserable part. At the end of the first day, I shed a tear and with my head in my hand said, 'This is not why I became an actor,' forgetting the mics were still on!"