Natalie Portman only agreed to take part in big budget comic adaptation 'Thor' after hearing Kenneth Branagh was directing.
The actress says she wasn't interested in doing another blockbuster movie after starring in the three 'Star Wars' prequels until she found out the British star was directing the movie adaptation of Marvel Comics' 'Thor'.
She explained: "It was sort of actually not something I was dying to do. Not 'Thor' in particular but a big movie. When I heard Ken was doing it, I said, 'Wow that is a daring and interesting idea.'
"Then I met Ken and he was someone I was extremely interested to get to spend three months with. It was probably the first, or one of the first times that my expectations were actually exceeded."
Natalie, 29, also admitted that she finds working with special effects challenging and thinks actors should be given lessons in how to work with a blue screen.
She said: "Working with blue screen and that whole universe is something that is a skill and something that you really need to practice. If acting schools were created today, that would be a technique that you would learn. And getting to experience that with Ken's guidance - who's the master of attacking text and character from every angle - was a new way to approach the blue screen acting. It was an exciting challenge to go at again."
'Thor' is due for release in May 2011.