Kenneth Branagh decided not to shoot 'Thor' in 3-D because of Chris Hemsworth's casting.

The director considered using the technology when filming the forthcoming superhero epic - which has been converted in post-production - but felt it would be too confusing when he had a relatively unknown actor in the lead role.

He said: "I researched it sufficiently to know we would be able to convert all of our shots but I didn't want to have two cameras and all the physics involved when I had a brand-new actor as 'Thor'."

Kenneth also revealed he considered quitting the project when the success of 'Iron Man' meant 'Thor's release was pushed back from summer 2010 to this year.

He said: "I seriously considered leaving."

Despite Kenneth's worries, Marvel Studios president Kevin Feige insisted delaying the project was a good thing.

He told The Hollywood Reporter: "It was beneficial because this is the most complicated film we have ever made, from the costumes to the set."

Kenneth was glad to stay on the project, though he admits he has no idea how the film will be received.

He said: "I've enjoyed it enormously and the commercial gods will have to decide whether it's a success."