When you write your Great American Novel, maybe you should think about how it will be adapted for the movies. At least a little bit.
Sometimes the difference between book and movie is so great as to make the finished product unrecognizable. Sometimes the adaptation is so bad, that the author doesn’t want to even be associated with the film, and a pseudonym is used. (In that case, I at least hope he was paid well for the rights, not to mention the indignity.)
The 142-minute megamovie 2001 was supposedly based The Sentinel, a 1948 short story by science fiction superstar Arthur C. Clarke. But if you had to hit the bathroom during the movie you might have missed THAT insignificant scene altogether. Clarke reportedly commented later that claiming 2001 was based on The Sentinel is like comparing "an acorn to the resulting oak-tree."
I had read and enjoyed The Sentinel years ago, in a favorite anthology of science fiction stories on which movies were based, REEL FUTURE The stories that inspired 16 classic science fiction movies. When I finally got around to watching 2001 on channel 2, some time AFTER the year 2001 had passed, I was VERY disappointed. I liked the PanAm part and the part based on The Sentinel, but the rest was a total bore.
But long before that, waaay back in elementary school, I saw Journey to the Center of the Earth after having read the Journey to the Center of the Earth paperback by Jules Verne. I was heartbroken! That was my first exposure to this kind of movie disappointment. I even wrote a report for school detailing all the differences between the book and the movie. At my very young age, I thought it was a big deal, a major scandal! Interestingly, the 2008 version has enough of the original movie to be considered a remake, but it’s plotted like a present-day sequel. It obviously has a lot more special effects, but is no more faithful to the book than the previous version.
Nowdays, I have predictably low expectations for movies that have been based on books I like, so I am seldom disappointed. Atlas Shrugged Part I is a notable exception, although it would have to be 24 hours long to include everything Ayn Rand put into the classic Atlas Shrugged! Atlas Shrugged Part II is coming this fall. I can’t wait!