Sam Taylor-Johnson and Jamie Dornan visited prostitutes to research Fifty Shades of Grey.
The movie's director was determined to make sure the kinky drama was portrayed as realistically as possible so she and the hunky actor spoke to real-life sex workers to gain an insight into their world.
She said: "Jamie and I met various dominants and dominatrix, just to make sure we understood that world, so that we in no way portrayed it incorrectly."
Part of Sam's research involved a thorough understanding of E.L. James' novel and she admits she has read the raunchy tome so often, she feels like she has "eaten" it.
She told Red magazine: "I've practically eaten it. I have read it over and over."
The 47-year-old filmmaker - who has daughters Angelica, 17, and Jessie, nine, with ex-husband Jay Jopling and Wylda, four, and Romy, two, with husband Aaron Taylor-Johnson - admitted her dedication to the project has left her going "out of her mind" because she has been so consumed with the movie.
She said: "I'm literally going out of my mind. I have seen this film over a thousand times and I'm now in a blancmange. But the nuances within - the tiniest shift, look, blink of an eye - can make all the difference and flip it into the wrong territory
"The moment I stepped out of the meeting [after accepting the movie], I stepped onto one of those bullet trains. The doors closed and I couldn't get off. The speed, the velocity, was unbelievable. I need to get off and breathe and think about something else."