Wildly successful novelist Seth Grahame-Smith has three Hollywood adaptations in the works. His most buzzed about movie, Abraham Lincoln Vampire Hunter, will be released to theaters June 22, 2012 and stars Dominic Cooper (Mamma Mia! and Captain America: The First Avenger) 
as Henry Sturgess and Benjamin Walker as Abraham Lincoln. There’s also Unholy Night, a dark twist on the three wise men, and Pride and Prejudice Zombies (another take on the popular 18th century Jane Austen novel). Unholy Nights is scheduled for release in May.
Some of Hollywood’s most popular and critically acclaimed movies have been adapted from novels including Gone with the Wind, The Color Purple, To Kill a Mockingbird and a surprising number of novels by sci-fi writer Philip K. Dick.
Hollywood is tapping into the book industry with renewed fervor, especially after successes resulting from adaptations of The Davinci Code, The Help, Harry Potter, the Twilight movies, and now The Hunger Games – to name a few (see list of Popular Books turned into movies here: http://www.goodreads.com/shelf/show/books-made-into-movies).
It almost seems like a no brainer, that a screenwriter in career limbo might want to try their hand at novel writing.This transition is no easy feat. Novels require a lot more thought, organization and detail than writing a screenplay, though one can argue that a transition in the reverse is even harder. Novelists must learn how to convey a story in fewer words, in present tense, and apply the one minute per page rule to a 90-120 page format. The biggest struggle for a novelist learning to write a script is sticking to a strict form of visual story telling, which is describing only what the viewer will see on screen.
I’ve experienced life as a writer on both sides of the fence. Paring down and adhering to the strict guidelines a screenplay requires is difficult. Novelists are used to having creative license… freedom and thus, slip into past tense references and narrating what characters are thinking or feeling. Screenwriting is a “visual” medium. A novelist must also learn to provide the immediacy a script needs while novels have the luxury of dragging out the plot.
In making the transition from script writing to novel writing, screenwriters sometimes struggle with detail. The good news is that you can saw the chains off, my friend. You’re allowed to write as many thoughts, motivations and internalizations as you want, so long as it suits the story. Old habits are hard to break so it takes a while to get comfortable writing in a new and sometimes unfamilar medium.
Whatever you do, don’t give up. Edit as many times as necessary and find an experienced reviewer or editor who will give you an honest critique.
The material Hollywood produces comes and goes in phases whether its a novel, comic books or video game adaptations, all which relies on audience retention for a succesful transition. Who knows how long the trend will last. Your job as a screenwriter turned author is to write the next best seller.
Good luck.
Source:
http://collider.com/unholy-night-seth-grahame-smith-book-trailer/156026/