I've only read the book Harry Potter and the Half Blood Prince once, and that was a few years ago now. After seeing this movie, I'm tempted to re-read it to see what choices I might have made in turning this story into a movie.
In making a movie from a book, choices always have to be made. Books are complex, they take time to describe the thoughts and feelings of characters, the motivations that are never outwardly shown, and there is room for digression, little side adventures that help build up the over all picture, but for which there isn't time in a movie.
On the other hand, a picture tells a thousand words. In a movie, there is no need to spend time describing a scene. It's there in front of our eyes. Besides, actors convey a lot, so even when we don't know exactly what they are thinking, we know roughly how the characters feel about something, and may even be able to recall the memory the character is recalling at a given moment that causes them to act as they do. The right word or phrase repeated at the right moment, the right shift in camera view as eyes glance aside, does a lot of the work.
These days, though, a lot of time is spent on the visual feast side of a movie, and the special effects, and the lessons of great movie makers like Hitchcock appear to be forgotten or put aside.
The Half Blood Prince is a case in point.
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