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Roll the credits: What does a movie gaffer actually do?

24 February 2012 Last updated at 00:10 GMT

At the Oscars there will be a high-profile battle for Hollywood's most coveted awards but what about the people lower down the credits?

BBC News went to meet some of these unsung heroes - a gaffer, a key grip, a property master and a digital compositor - to find out what they do and how they contributed to some of the films nominated this year.