At the same time, I think there is an interesting magic that occurs when a short story is made into a feature length film.
In fact, I would suggest that a film based on a short story is far more likely to be successful than a feature length film based on a novel.
I can usually quickly identify a feature length film that is based on a short story. In school I remember learning that a short story is a film with minimal characters (usually only one that is truly developed) minimal settings (usually only one), takes places in only one time (no major time change), and can be read in one sitting.
So when a screenwriter and director take a short story instead of being confined the tons of plot details and characters, instead they are given the freedom that comes with the shell of a story that they can then give texture too, as opposed to be bound by pages of descriptions, characters, and dialogue that readers will hold them to.
Additionally, because these short stories tend to be less popular, film makers can take some one else's wonderful story and make it there own with out readers guaging their adaptation up to the original work (how often do you hear "the movie wasn't as good as the book" the reason primarily being is the movie's feature format was forced to leave out moments readers found essential).
Here's some examples of short stories made into feature length films (old & new):
- The Most Dangerous Game (1932) [based on "The Most Dangerous Game" by Richard Connell]
- It Happened One Night (1934) [based on "It Happened One Night" by Samuel Hopkins Adams]
- Mr. Deeds Goes to Town (1936) [based on "Opera Hat" by Clarence Budington Kellan]
- All That Money Can Buy (1941) [based on the "The Devil and Daniel Webster" by Stephen Vincent Benét]
- It's A Wonderful Life (1946) [based on "The Greatest Gift" by Phillip Van Doren Stern"]
- All About Eve (1950) [based on "The Wisdom of Eve" by Mary Orr]
- Roshomon (1950) [based on "Roshomon" and "In A Grove" by Ryûnosuke Akutagawa]
- Rear Window (1954) [based on "It Had to Be Murder" by Cornell Woolrich]
- Seven Brides for Seven Brothers (1964) [based on "The Sobbin' Women" by Stephen Vincent Benét]
- 3:10 to Yuma (1957) [based on "Three-Ten to Yuma" by Elmore Leonard]
- The Fly (1958) [based on the "The Fly" by George Langelaan]
- Breakfast at Tiffany's (1961) [based on "Breakfast at Tiffany's" by Truman Capote]
- The Birds (1963) [based on "The Birds" by Daphne Du Maurier]
- 2001: A Space Odyssey (1968) [based on "The Sentinal" by Arthur C. Clarke]
- The Man Who Would Be King (1975) [based on "The Man Who Would Be King" by Rudyard Kipling]
- Memento (2000) [based on "Memento Mori" by Jonathan Nolan)
- A.I. (2001) [based on "Supertoys Last All Summer Long" by Brian Aldiss]
- In the Bedroom (2001) [based on "Killing" by Andre Dubas]
- The Emperor's Club (2002) [based on "The Palace Theif" by Ethan Canin]
- Minority Report (2002) [based on "The Minority Report" by Philip K. Dick]
- The Million Dollar Baby (2004) [based on "Million $$$ Baby" by F.X. Toole]
- Brokeback Mountain (2005) [based on "Brokeback Mountain" by Annie Proulx]
- Away from Her (2006) [based on "The Bear Came Over the Mountain" by Alice Munro]
- The Illusionist (2006) [based on "Eisenheim the Illusionist" by Steven Mullhauser
- The Curious Case of Benjamin Button (2008) [based on The Curious Case of Benjamin Button by F. Scott Fitzgerald]