This is a film is about the instantaneous capturing of a scene is the cameras greatest strength. The downfall of this gift is that the perfect moment has usually come and gone within a second or two. The beauty of this is that you can capture almost any event no matter how brief.
The trick is not only capturing the perfect moment on film but also doing so with great composition.
This is why it is imperative that photographers learn how to think very quickly. Slowly but surely the cameras manual settings will come naturally to you and you can set your camera up for any condition almost immediately.
Henri Cartier-Bresson was a master of this.
Learn more about Henri Cartier-Bresson here.
Here is a video about his famous book The Decisive Moment: