Fifty Shades of Grey film premieres in Berlin

Taylor-Johnson (right) previously directed the Beatles-based biopic Nowhere Boy

The film version of erotic novel Fifty Shades of Grey has premiered at the Berlin Film Festival in Germany.

Novelist EL James attended the event with director Sam Taylor-Johnson and stars Jamie Dornan and Dakota Johnson.

"It's an extremely romantic movie and at the heart of it, it is a love story," Taylor-Johnson told reporters. "I think we've got that balance right."

The 18-certificate film has its UK premiere in London later, ahead of a worldwide release on 13 February.

Accompanied by her husband, actor Aaron Johnson, Taylor-Johnson - formerly Taylor-Wood - said she was "very nervous and excited" at the thought of screening the film to an international audience

The visual artist turned film-maker said she was "proud of what we've achieved" and "proud of [her] cast", which also includes singer Rita Ora and Oscar-winning actress Marcia Gay Harden.

James's Fifty Shades trilogy details the sadomasochistic affair between a young student, Anastasia Steele, and a billionaire businessman, Christian Grey.

Often sneered at as "mummy porn" for its explicit sex scenes, the British author's books have sold more than 100 million copies worldwide.

Reviews for the film have ranged between one and four stars. The Guardian called it "the most purely tasteful and soft-core depiction of sadomasochism in cinema history", while the Telegraph said it had "worked out... almost shockingly well".

Taylor-Johnson, however, insisted she "never" reads reviews. "I just don't bother with them anymore," she told reporters in Berlin.

Author EL James said she was looking forward to having "a gin and tonic"

"You can read really lovely things, and then one bad review stays with you forever. You focus on that and don't think about what's positive.

"I'm much more concerned with what fans will think. This movie is dedicated to them and I hope they like it."

Those fans waited all day on Wednesday outside Berlin's Zoo Palast theatre, some armed with flowers and copies of the books.

'Something classy'

Dornan, who previously played a serial killer in BBC drama The Fall, said he was prepared for the additional attention playing Grey would bring.

"I accepted that this role would change my life when I took the part," said the Northern Irish actor. "Although when you see the way fans are reacting, it hits you afresh.

"However, I'm still the same person I was before I was Christian Grey. I have a wife and a child and my circle of friends are the same. I'm not going anywhere."

Fifty Shades of Grey is released worldwide on 13 February

Speaking on the red carpet, the actor acknowledged "the book and the film aren't to everyone's taste".

"But that's fine," he continued. "I think we've done something classy."

"It's very important that everyone who might wish to judge remembers that Anastasia acts of her own free will in the movie," said co-star Dakota Johnson. "It's a story where everything that happens between these two people is consensual."

The 25-year-old said her parents, actors Don Johnson and Melanie Griffith, had yet to see the movie but were "very proud" of her.

'Not easy'

An estimated 4.5 million tickets have already been sold in the 39 countries where Fifty Shades of Grey will be released this weekend.

Taylor-Johnson confirmed she is in talks to direct the next two films of the trilogy but said nothing had been decided "as yet".

James said she was "excited" but "hated" being the centre of attention. "To be honest, I'm looking forward to going home later and reading all about it with a gin and tonic," she revealed.

The best-selling novelist, whose real name is Erika Mitchell, said she had had "input as a producer from the first to last frame".

"What you see up there, I had a say in all of it," she declared.

In an interview with the Hollywood Reporter, Taylor-Johnson admitted she and James had clashed during shooting and that making the film had been "an incredibly painful process".

"We'd often clash and have to find a way to work through that to get to some sort of resolution," she is quoted as saying. "She would be the first to say as well that it was not easy."