Editing Perspective distortion (section)

== Artistic uses ==
=== Technical background ===

[[File:Focal length.jpg|thumb|How [[focal length]] affects perspective: 18&nbsp;mm ([[wide angle lens|wide-angle]]), 34&nbsp;mm ([[normal lens|normal]]), and 55&nbsp;mm ([[telephoto lens|modest telephoto]]) at identical [[field size]] achieved by different camera-subject distances. Notice that the shorter the focal length and the wider the [[angle of view]], '''perspective distortion''' and size differences change.]]Although perspective distortion is often annoying when unintended, it is also intentionally used for artistic purposes. Extension ([[wide-angle lens|wide angle]]) distortion is often implemented to emphasize some element of the scene by making it appear larger and spatially removed from the other elements. Compression ([[telephoto lens|telephoto]]) distortion is often used to give the appearance of compressed distance between distant objects, such as buildings or automobiles in order to convey a feeling of congestion. Longer lenses magnify the subject more, apparently compressing distance and (when focused on the foreground) blurring the background because of their shallower [[depth of field]]. Wider lenses tend to magnify distance between objects while allowing greater depth of field.

Another result of using a wide-angle lens is a greater apparent perspective distortion when the camera is not aligned perpendicularly to the subject: parallel lines converge at the same rate as with a [[normal lens]], but converge more due to the wider total field. For example, buildings appear to be falling backwards much more severely when the camera is pointed upward from ground level than they would if photographed with a normal lens at the same distance from the subject, because more of the subject building is visible in the wide-angle shot.

Because different lenses generally require a different camera–subject distance to preserve the size of a subject, changing the [[angle of view]] can indirectly distort perspective, changing the apparent relative size of the subject and background. If identical [[field size]] is maintained, wide-angle lenses make subjects appear larger by introducing size differences along with the converging lines mentioned above, and they make rooms and spaces around the subject appear more vast by increasing the distance between subject and background (expanded perspective).

=== Mood effect and famous uses ===

The mood effect of perspective distortion achieved by [[rectilinear lens|rectilinear]] extreme wide-angle lenses is that the resulting image looks grotesque and unsettling, while not looking as unrealistic as [[curvilinear perspective|curvilinear]] [[fisheye lens]]es which display [[barrel distortion]]. The effect is especially noticeable the closer the camera is to the subject, as its amount increases the shorter the focal length is at the same field size.

One notable director that frequently employs rectilinear [[ultra wide angle lens]]es in order to achieve a distinctive signature style defined by extreme perspective distortion is [[Terry Gilliam]]. Also [[Stanley Kubrick]] (in ''[[Paths of Glory]]'', and ''[[Dr. Strangelove]]'', among others) as well as [[Orson Welles]] (in ''[[The Trial (1962 film)|The Trial]]'', partly ''Orson Welles' London'', segment ''Four Clubmen''), [[Sam Peckinpah]] (in ''[[Straw Dogs (1971 film)|Straw Dogs]]''), and [[Sidney Lumet]] (in ''[[The Offence]]'') have occasionally done the same in the past, though mostly in moderation, for single shots or sequences only, while Gilliam hardly ever uses any lens longer than 14&nbsp;mm, which has garnered lenses of that particular focal length the informal nickname ''"The Gilliam"'' among film-makers.<ref>Stubbs, Phil: [http://www.smart.co.uk/dreams/tidegill.htm "Terry Gilliam talks ''Tideland''," ''Dreams'']</ref> [[Jean-Pierre Jeunet]] and [[Marc Caro]], two French filmmakers influenced by Gilliam, adopted his typical wide-angle photography in their two most "Gilliamesque" features, ''[[Delicatessen (1991 film)|Delicatessen]]'' and ''[[The City of Lost Children]]''. Orson Welles's ''The Trial'' is notable for heavily influencing Gilliam's signature style years before the American ex-patriate joined the [[Monty Python]] comedy troupe while only being a one-feature style for Welles.

Due to the grotesque, unsettling mood effect peculiar to wide-angle lenses, films making use of such perspective distortion can often be placed in one of two categories: Grotesque and surreal satire and fantasy, also to some extent black comedy (Gilliam, Jeunet & Caro, Orson Welles, ''Dr. Strangelove'') on the one hand, and serious, more realistic films with a particular edge for [[social criticism]] on the other, whereas social conventions, collective society, and/or the motives and acts of leaders are portrayed as grotesque and absurd, and often also feature tyrannical characters with conformist values who act out in an extremely hostile and prejudiced way towards individualism and outsiders (''Paths of Glory'', ''Straw Dogs'', ''The Offence'').

On the other end of the focal length spectre, [[Leni Riefenstahl]] used extreme [[telephoto]] lenses to compress large crowds in ''[[Triumph of the Will]]'' while the ''Führer'' [[Adolf Hitler]] is seen through normal lenses and often from a [[low-angle shot|low angle]] to appear tall in comparison.

In cinematography, perspective distortion also has bearing on the in-camera [[special effect]] known as the [[dolly zoom]], in which a [[zoom lens]] zooms out at the same time as the camera moves toward the subject, in such a way as to keep the subject the same size in the frame while the background "changes size" relative to the subject.  This effect was made popular in the films ''[[Vertigo (film)|Vertigo]]'' and ''[[Jaws (film)|Jaws]]''. Another example of this can be seen in the first ''[[The Lord of the Rings: The Fellowship of the Ring|Lord of the Rings]]'' film, just before the [[Nazgûl|Black Rider]] comes down the road.  The dolly zoom is used to create a compression effect in the road.

=== Examples ===

The photo below of the gondolas is an illustration of the use of extension distortion, and the photo of the buildings below it is an example of compression distortion.
<gallery mode="packed" heights="250">
File:Gondolas.jpg|An example of "wide angle" distortion used for artistic purposes. Created by an 18&nbsp;mm lens on a full-frame 35&nbsp;mm camera.
File:Nybldgs.jpg|An example of "telephoto" distortion used for artistic purposes. Created by a 300&nbsp;mm lens on a full-frame 35&nbsp;mm camera.
</gallery>