Novels don't often make as good a movies as shorter works do.

"Dune" was made from a novel, cut to fit a movie format. (It actually had a series of novels to draw on.)
"Blade Runner" and "2001, A Space Odyssey" were expanded from short stories.

Some of the best movies are explorations of a simple concept.

A good novel, in my humble opinion is a much much more complex and cerebral work.
I think that the more ground is covered in a Novel, the less likely it is to become a good screenplay.