'Fifty Shades of Grey' stars Dakota Johnson and Jamie Dornan have ''chemistry'' off-set.

The film's producer Michael De Luca believes the pair - who play lovers Christian Grey and Anastasia Steele - are ''hot'' together and get on really well both on camera and away from filming.

He said: ''The chemistry is there, they genuinely like each other. They're enjoying the story, the story is so powerful.''

The film adaptation of E.L. James' erotic novel is expected for release in February 2015, and De Luca admits they're already over half-way through shooting.

He told E! news: ''I think we are a little more than halfway through but it's going really good. I'm excited!''

Meanwhile, E.L. James recently admitted she feels huge pressure for Sam Taylor-Johnson's upcoming movie of her best-selling book to be a success and she is determined to get things ''right''.

She said previously: ''I'm terrified. Completely. I've been terrified from the moment I published the book. My mother was terrified of everything, and so am I. It's a terrible way to grow up. You don't expect this kind of success.

''Even now it floors me. My only ambition for the books was to see them in bookstores. This is huge. And there is this passionate fandom; we need to get this right for them.''