Vertigo Effect = Dolly zoom

(also called as a Dolly zoom, Back zoom-travelling, Jaws shot, Contra-zoom or even Hitchcock-zoom )

The much-imitated vertigo effect was achieved by a combination of zooming forward and tracking backward simultaneously. After much trial and error, filming on a full-size set proved impossible, so they used a large-scale model of a staircase. Turned on its side, it was filmed by special effects cameraman John Fulton to make the audience feel as dizzy as Jimmy Stewart.

Vertigo DVD

On the other hand, Wikpedia says:

Uncredited second-unit cameraman Irmin Roberts invented the famous “zoom out and track in” shot (now sometimes called “contra-zoom” or “trombone shot”) to convey the sense of vertigo to the audience. The view down the mission stairwell cost $19,000 for just a couple of seconds of screen time.

History

Invention of the dolly zoom is credited to cameraman Irmin Roberts. The technique was made famous by Alfred Hitchcock (Vertigo being the best-known example), and was used by Steven Spielberg in Jaws and ET. Many other directors have used the technique, which brings us to an important warning…

The dolly zoom effect is an unsettling in-camera special effect that appears to undermine normal visual perception in film.

The effect is achieved by using the setting of a zoom lens to adjust the angle of view (often referred to as field of view) while the camera dollies (or moves) towards or away from the subject in such a way as to keep the subject the same size in the frame throughout. In its classic form, the camera is pulled away from a subject whilst the lens zooms in, or vice-versa. Thus, during the zoom, there is a continuous perspective distortion, the most directly noticeable feature being that the background appears to change size relative to the subject.

As the human visual system uses both size and perspective cues to judge the relative sizes of objects, seeing a perspective change without a size change is a highly unsettling effect, and the emotional impact of this effect is greater than the description above can suggest. The visual appearance for the viewer is that either the background suddenly grows in size and detail overwhelming the foreground; or the foreground becomes immense and dominates its previous setting, depending on which way the dolly zoom is executed.

The effect was first developed by Irmin Roberts, a Paramount second-unit cameraman, and was famously used by Alfred Hitchcock in his film Vertigo.

Mathematics

To achieve the effect the camera needs to be positioned at a certain distance from the object that is supposed to remain still during the dolly zoom. The distance depends on how wide the scene is to be filmed, and on the field of view (FOV) of the camera lens. Before calculating the distances needed at the different field of views, the constant width of the scene has to be calculated. For example, a FOV of 90° and a distance of two meters yield a constant width of four meters, allowing a four-meter-wide object to remain still inside the frame during the effect.

 \mathit{distance} = \frac{\mathit{width}}{2\cdot \tan(\frac{\mathit{fov}}{2})}

Dolly Zoom

Different angles in a dolly zoomA dolly zoom is a cinematic technique in which the camera moves closer or further from the subject while simultaneously adjusting the zoom angle to keep the subject the same size in the frame. The effect is that the subject appears stationary while the background size changes (this is called perspective distortion).

In the first example pictured, the camera is positioned close to the subject and the lens is zoomed out. In the second shot, the camera is several metres further back and the lens is zoomed in.

The Effect

Dolly zooms create an unnatural effect — this is something your eyes would never normally see. Many people comment on the shot after seeing it for the first time, e.g. “That was weird” or “What just happened there?”.

The exact effect depends on the direction of camera movement. If the camera moves closer, the background seems to grow and become dominant. If the camera moves further away, the foreground subject is emphasized and becomes dominant.

The effect is quite emotional and is often used to convey sudden realisation, reaction to a dramatic event, etc.

http://www.mediacollege.com/video/shots/dolly-zoom.html

The vertigo effect has influenced lot of directors and films.  Dolly Zoom shot examples: Jaws, Poltergeist, Goodfellas, and The Fellowship of the Ring.

Short Video:

(Hitchcock’s vertigo effect inspired: Steven Spielberg, Tobe Hooper, Martin Scorsese, Peter Jackson)

Questions arises:

1. What was the audience first respond to the vertigo effect?

2. Is the vertigo effect similar to the vertigo disease?

References:

http://www.mediacollege.com/video/shots/dolly-zoom.html

http://en.wikipedia.org/wiki/Dolly_zoom

http://www.imdb.com/title/tt0052357/trivia

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