The young actress, who gently gazes from the cover of Vogue's February issue, told the fashion mag that she relishes not being identified in London and often thinks about her "dwindling anonymity."
"That's really scary because a very large part of me would be perfectly happy living on a ranch in Colorado and having babies and chickens and horses -- which I will do anyway," the 25-year-old "Social Network" actress said.
But it was hard for her to pass up the possibly career-making role as college-student ingenue Anastasia Steele, the central character in the big-screen adaptation of E.L. James' wildly popular bondage and domination trilogy.
"I wanted to be involved because it's so different," she said of the character, whom she feels so many people think they personally know. "And it's an intense love story."
Johnson, who is currently dating Welsh guitarist Matthew Hitt, spent 9¿¿ weeks shooting the steamy film. She's said to have major chemistry with costar Jamie Dornan, who stepped in to play sexually charged billionaire Christian Grey after
"It looks beautiful," she added. "I've never seen anything like it. But it's confusing to the brain -- I still can't look at it objectively or wrap my head around it. The parts of the movie that are difficult to watch were even more difficult -- and emotionally taxing -- to shoot."
Parts that involve "sexual acrobatics" actually. Red room of pain, anyone?
Still to come: the film's whirlwing promotional tour ahead of its international debut at the Berlin Film Festival on Feb. 11 and stateside release on Valentine's Day weekend.
"It's just the most insane thing to be a part of," she added. "I've never experienced anything like this; I don't think anyone has. It's terrifying -- and it's exciting."
It's surprising she says that, given her famous upbringing and rather Hollywood-style breeding. Her mother is
Johnson traveled "everywhere" growing up with her parents, who took her to their globe-spanning film sets.
"I was always taken in and out of school," she said, knowing that she'd ultimately take up her parents' line of work. "I just assumed that what I would be doing is making films because I grew up around people making films, making art, making music. And being on a film set is the most comforting thing in the world to me. Seeing a catering truck feels like home."