Yahoo! has an interesting article about the role of authors when Hollywood decides to put their books on the big screen:
So it was, and so it almost always is: Authors write books. Screenwriters write screenplays. And while there are strong exceptions to every rule (Herman Wouk, Larry McMurtry), a savvy author tends to know when to step aside and let the filmmakers take charge — or, in some cases, the sausage makers. For some reason, authors tend to refer to pork products when discussing Hollywood.
Zoe Heller, author of “What Was She Thinking?: Notes on a Scandal: A Novel” (now “Notes on a Scandal”), shared a few notes with screenwriter Patrick Marber but kept away from much of the production. “I didn’t want to be a fifth wheel lurking around the set,” she says. “It’s a bit like that old line about seeing sausages made: The sausage may be highly delicious when it comes out, but I didn’t necessarily want to be involved in the sausage-making process.”
Whether in the sausage factory or not, authors say they try to detach their mental ownership of the stories from the film versions. Assured that their novel is out on the shelves, they do some self-convincing that what goes up on the screen is from another universe.
Ultimately, watching a professionally made, well-acted version of their story takes some of the sting away.
Link to the Yahoo! News article