Dolly zoom

The effect was first conceived by Alfred Hitchcock during the filming of 1940's Rebecca, but he was unable to achieve the desired results. Some 18 years later, success came through Irmin Roberts, a Paramount second-unit cameraman, who devised the proper method for Hitchcock's film Vertigo.[7] It is thought that Alfred Hitchcock specifically asked Roberts to assist him in creating a shot that exemplifies being in a drunk state after fainting at a party.[8] At the time, Roberts had already designed a special camera capable of fast focal lens changes that allowed short-range projections. His expertise in focal lenses most likely prompted his innovation of the dolly zoom, which was more popularly recognized as the "trombone shot" or "contra zoom". Despite this step forward for cinematography, Roberts was not properly credited at the end of Vertigo.[9] However, this shot has since been used in many other films, including Goodfellas,[10] Jaws,[4] and the Lord of the Rings films. Rainer Werner Fassbinder uses the effect twice in one shot in Chinese Roulette (1976). Director Joe Dante referred to it as the "Jaws Shot" since the scene in Jaws, when Roy Scheider sees the shark attack of the little boy Alex, is the most famous use of this shot.

Uses

The first dolly zoom used in "Vertigo" by Alfred Hitchcock, shot by Irmin Roberts

Among the many creative uses the dolly zoom can provide to cinematographers, the shot can be divided into two types: the dolly-in/zoom-out and the dolly-out/zoom-in. The dolly-in/zoom-out shot is usually centered on a subject, where the background is pushed away from the character to create a profuse amount of uneasiness. For example, the movie Poltergeist's infamous dolly zoom stretches the background to seem as if the door is much farther away from the character than it actually is. On the other hand, the dolly-out/zoom-in shot shrinks the background to seem much closer than it really is.[6]

The dolly zoom is commonly used by filmmakers to represent the sensation of vertigo, a "falling-away-from-oneself feeling" or a feeling of unreality, or to suggest that a character is undergoing a realization that causes them to reassess everything they had previously believed. In general, the dolly zoom's amplification of emotion is a special effect that compliments a director's arsenal of creativity. For example, in Sam Raimi's The Quick and the Dead, a dolly zoom, coupled with a Dutch angle shot, exemplifies drama between an intense shootout. An uneasy feeling of suspense can also be signified through a dolly zoom, most notably used in the movie Split in 2018, where Casey Cooke peers off into the distance in unwanted curiosity. Other uses include demonstrating overwhelming fear or important epiphanies for a character.[8] The dolly zoom can also be utilized for the purposes of tonal shifts within the film. This was most exemplified in The Lord of the Rings: The Fellowship of the Ring, where director Peter Jackson chained events together with more flare as opposed to a regular transition. Directors may also decide to use the dolly zoom as an alternative to the generic wide shot in order to give sufficient exposition on the upcoming scene.

For most purposes, it can be assumed that the image space and the object space are in the same medium. Thus, for an object in focus, the distance between the lens and image plane ${\displaystyle s_{\text{i}}}$, the distance between lens and the object ${\displaystyle s_{\text{o}}}$, and the focal length ${\displaystyle f}$ are related by

${\displaystyle {1 \over s_{i}}+{1 \over s_{o}}={1 \over f}.}$

Then the transverse magnification is

${\displaystyle M={s_{\text{i}} \over s_{\text{o}}}={f \over (s_{\text{o}}-f)}.}$

The axial magnification ${\displaystyle M_{\text{ax}}}$ of an object at ${\displaystyle s_{\text{o}}}$ is the rate of change of the lens–image distance ${\displaystyle s_{\text{i}}}$ as the lens–object distance ${\displaystyle s_{\text{o}}}$ changes. For an object of finite depth, one can conceive of the average axial magnification as the ratio of the depth of the image and the depth of the object:

${\displaystyle M_{\text{ax}}=\left|{d \over d(s_{\text{o}})}{s_{\text{i}} \over s_{\text{o}}}\right|=\left|{d \over d(s_{\text{o}})}{f \over (s_{\text{o}}-f)}\right|=\left|{-f \over (s_{\text{o}}-f)^{2}}\right|={M^{2} \over f}.}$

One can see that if magnification remains constant, a longer focal length results in a smaller axial magnification, and a smaller focal length in a larger axial magnification. That is, when using a longer focal length while moving the camera/lens away from the object to maintain the same magnification M, objects seem shallower, and the axial distances between objects seem shorter. The opposite—increased axial magnification—happens with shorter focal lengths while moving the camera/lens towards the object.