Dakota Johnson is opening up about what it was really like to film "Fifty Shades of Grey."

In a recent interview with Vanity Fair, Johnson admitted that E.L. James, author of the book series, was more than a little difficult to work with. She confessed,

"I signed up to do a very different version of the film we ended up making."

Johnson cites a "combo" of the studio, director, and author rewriting behind the scenes that made the process chaotic, mostly stemming from James' familiarity with prose as opposed to screenplays. Johnson explained,

"She had a lot of creative control, all day, every day, and she just demanded that certain things happen. There were parts of the books that just wouldn't work in a movie, like the inner monologue, which was at times incredibly cheesy. It wouldn't work to say out loud. It was always a battle. Always."

The situation became complicated after original lead actor, Charlie Hunnam, left production and was replaced by Jamie Dornan. According to Johnson, James scrapped the entire script following his exit, elaborating,

"We'd do the takes of the movie that Erika wanted to make, and then we would do the takes of the movie that we wanted to make. The night before, I would rewrite scenes with the old dialogue so I could add a line here and there. It was like mayhem all the time."

It wasn't the content that almost made Johnson scream her safe word, but the process itself. Still, she maintains that she's still proud of the work she's produced, and grateful for James all the same.

"If I had known at the time that's what it was going to be like, I don't think anyone would've done it. It would've been like, ‘Oh, this is psychotic.' But no, I don't regret it. Erika is a very nice woman, and she was always kind to me. And I am grateful she wanted me to be in those movies."