First Look at Anthony Hopkins and Tom Hiddleston in Thor!

"We came to feel that in our case 3-D could be the very good friend of story and character for a different kind of experience," Branagh said, taking a break from post-production. The filmmaker said the terminology of the 3-D process initially made him cringe -- at first, it was "math and physics and way over my head," he said with a chuckle -- but then he started to pulse with the unexpected artistic opportunities.

"It's another draft of the story that can reveal itself in a different way," he said. "I had a healthy degree of skepticism up front ... I've become somebody extremely excited about working with possibilities of doing it this way."

"I think it tends to be overused and can be a little bit gimmicky," said Johnston, who began shooting last week in London but will travel to San Diego for Marvel's Comic-Con panel. "A lot of people are using 3-D now because they feel have they have to ... that will come and go and the pictures that deserve to be in 3-D will continue to be. When it's done bad, it can make you carsick."