Walking down the red carpet at the premiere for her new film, "Sky Captain and the World of Tomorrow," Gwyneth Paltrow (search) said her most rewarding role is at home.

"I'm spending as much time as possible with Apple, carrying her around, singing to her, all kinds of things," the Oscar-winning actress said of her daughter with husband, Coldplay leader singer Chris Martin (search).

Paltrow left baby Apple, born in May, long enough to accompany co-star Jude Law (search) to the premiere of the fantasy adventure film in London's Leicester Square on Monday.

The pair found themselves acting largely against blue screens with minimal props as they portrayed a reporter and her fighter pilot ex-boyfriend, who tackle a computer-generated robot invasion from outer space.

"At first it was tricky and it was difficult to keep a straight face, then we got used to it," Law said.

Added Paltrow: "It's a difficult technique but it was actually fun. You've just got to use your imagination."