Sir Ian McKellen has confessed that he broke into tears of despair on the set of The Hobbit, .

McKellen, who has played Gandalf since Peter Jackson’s first “Lord of the Rings” film, became irritated when he had to film scenes in “The Hobbit” with a green screen instead of actual actors. Gandalf, a wizard who stands higher than the dwarfs and hobbits in the narrative, couldn’t be on the same set as them.

“In order to shoot the dwarves and a large Gandalf, we couldn’t be on the same set,” McKellen told Contact Music. “All I had for company was 13 photographs of the dwarves on top of stands with little lights – whoever’s talking flashes up. Pretending you’re with 13 other people when you’re on your own, it stretches your technical ability to the absolute limits.”

“I cried, actually. I cried. Then I said out loud, ‘This is not why I became an actor’. Unfortunately the microphone was on and the whole studio heard.”

When he returned to the studio the next day, he saw everything had been made nice, ‘The next day I went into my little tent and it had all been decorated beautifully. Remnants of Rivendell, carpets and cushions, fresh fruit and flowers, things that were hanging. It was lovely’.

McKellen is now on the road promoting ‘The Hobbit: An Unexpected Journey,’ the first of three films based on Tolkien’s novel.

The Hobbit will be released on December 13 in the United Kingdom and the United States.

The Desolation Of Smaug, Jackson’s second Hobbit film, will be followed by There And Back Again in July 2014. The films also star Martin Freeman as Bilbo Baggins and Benedict Cumberbatch, Cate Blanchett, Bret McKenzie, and Orlando Bloom, in addition to McKellen.