Daniel Craig enjoyed working on 'The Girl...'

Los Angeles: Actor Daniel Craig has said though 'The Girl with the Dragon Tattoo' was a serious film, he had fun shooting for it.

Craig insists that the shoot was defined by moments of lightheartedness. In many ways, he notes, the darker the material, the more frequent the fun.

"The more serious the subject matter the more likely you are to have fits of giggles, just from the very nature of it," he said.

"David (director David Fincher) likes to keep things light on set although when things get too distracting he brings it back. You need to know when to laugh and when to keep quiet. You keep your concentration up and occasionally you let off steam. It was intense," he added.