I happened to read this book Twilight recently. Considering that I read a good number of books ;) I was late in reading twilight. Though, the story of a human falling in love with a vampire was not that appealing to me. The other thing was that I had already seen the movie which was not exactly that gripping story wise or taking wise. But, as I started reading the book, I found that it was an easy and breezy read. A very entertaining book. I was really taken by the way the author portrayed the character of the narrator Isabella Swan. Her balancing problems, the way she gets obsessed with the character called Edward Cullen. It was all very good to read. The humor which the author created through the role of the girl was really good. But then I was left wondering one thing after I finished with the book. Why wasn't it that good when I saw it on screen? This reminded me of the few other movies that were made based on the books that I read. Angels and demons, One night @ call center, and the Harry Potter series. Almost each of the movies was a disappointment considering the scale on which the book stimulated my mind.
In the case of angels and demons the book itself was so big that it couldn't be made into a proper feature film in the first place. So, they cut out huge chunks of the book that had the vital part of the story. The major reason why this very successful book was not received that well as a movie is that, it failed to stimulate the same imagination it evoked in the mind of the person who read the book first.
In the case of a more local Indian book. One night@ call center by Chetan Bhagat, the characters were totally morphed and modified. With bad taking and unnecessary songs they made a mess out of a very beautiful modern Indian book.
The case of harry potter is pretty much like angels and demons. The whole series of books has such a huge set of characters and situations which are impossible to show on a screen in a span of a few hours. But, the reason for the huge success of this series of movies is that, they gave faces to the very well known characters of the book. For example, we can never imagine Harry Potter without Daniel Radcliffe.
So where it concludes is that, books can never create the same impact on screen. It is because, when you write, sky is the limit. Your imagination has no bounds. But when it comes to making movies, you have limits. You have a budget and a limited scope. Successful book adaptions are the ones which create the same environment in the mind of the person who read the book.