h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

A similar, less dramatic effect is the rack focus. While not as visually stuning, the rack focus can be used very dramatically.

It's simply when the camera quickly changes focus from foreground to background or vise-versa to accentuate dramatic action. It's a much simpler technique but when used correctly can be very effective.

What is amazing is how new both these techniques are.

Both effects only became widely used in the 1970's and 1980's. Richard Rush used the Rack Focus technique to great effect in The Stunt Man. Since then, it's a fairly common technique.

Before Jaws few had seen the "Trumbone effect".

Now both are widely used if not over used.

The fact that both of these in camera effects have only been used in the last 30 years of cinema is somewhat amazing. Of course it's important to note that until the 1960s most films were shot with static cameras.