^^ 25-30% might be too high actually. TBH I am not sure
3D accounts for say 45% of the gross and is certainly more expensive than 2D.
Also I don't understand why many movies are still filmed in 2D and post-converted to 3D. Even Iron Man 3 and the Avengers were filmed in 2D and converted afterward. Is it because the 'film like' quality is lost because they are using a 3D camera instead of 2D 35mm?
Converting a 2D movie to 3D takes 700 people 9 months (Jurassic Park 3D) - thats got to be a lot of money that does not need to be spent if you filmed in 3D to start with?