In the new film Girl With a Pearl Earring (opening Dec. 12), Colin Firth wears '60s-style fashions — the 1660s, that is — for his role as Dutch painter Johannes Vermeer. You may recall that in Love Actually, he looked shabby chic — here, he's just plain shabby! Apart from wardrobe, though, he says there's very little difference between making modern films and period pieces.

"I don't pay much attention to what the period is," the 43-year-old British actor says. "I find that a story is a story, and that the when of when it's set is a convention that's been provided just to tell a story in a particular way."

In fact, Firth is not even sure what defines a film as a period piece — much to his mother's dismay. "I don't know when 'period' starts," he admits. "I did a Terence Rattigan play [The Deep Blue Sea] which was set in the year of 1952. When I mentioned it to my mother that I was doing that, I described that as period. She was somewhat hurt, because this was her period, and she wasn't really ready to have it characterized as a costume drama just yet."

Despite his confusion over dates, he's still dedicated to achieving an authentic period look, even when it means sporting a very scraggly hairstyle. "I think," he laughs, "that a man who's willing to wear the wig that I did in Girl With A Pearl Earring is willing to do just about anything!"

Firth's bedraggled artist look was mocked by co-star Scarlett Johansson, whose knowledge of American TV commercials clearly surpasses his own. "A lot of [the taunting] was directed at my wig — and she called me Fabio for some reason," he chuckles. "And what I thought was my sizzling look was met with a smirk and [her saying], 'I can't believe it's not butter.'"