Manner of exposing motion picture film that determines aspect ratio
A comparison of 4-perf, 3-perf and 2-perf 35 mm film formats
Negative pulldown
is the manner in which an image is exposed on a
film stock
, described by the number of
film perforations
spanned by an individual frame. It can also describe whether the image captured on the negative is oriented horizontally or vertically. Changing the number of exposed perforations allows a
cinematographer
to change both the
aspect ratio
of the image and the size of the area on the film stock that the image occupies (which affects image clarity).
The most common negative pulldowns for
35 mm film
are 4-perf and 3-perf, the latter of which is usually used in conjunction with
Super 35
. 2-perf, used in
Techniscope
in the 1960s, is enjoying a slight resurgence due to the birth of
digital intermediate
techniques eliminating the need for optical lab work. Vertical pulldown is overwhelmingly the dominant axis of motion in cinematography, although horizontal pulldown is used in
IMAX
,
VistaVision
(still in use for some visual effects work), and in
35 mm
consumer and professional
still cameras
.
Usage of various formats
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History
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The majority of 35 mm film systems,
cameras
,
telecine
equipment,
optical printers
, or
projectors
, are configured to accommodate the 4-perf system; each frame of 35 mm is 4 perforations long. 4-perf was (and remains) the traditional system, and the majority of projectors are based on 4-perf, because 4 perforations is the amount needed per frame vertically in order to have enough negative space for a roughly squarish image, which became the
silent film
standard
aspect ratio
of 1.33:1.
Later, when the film industry was facing the perceived threat of obsolescence to
television
, universally a 1.33:1 aspect ratio at the time (and remained so in many countries until the introduction of
DTV
), studios started experimenting with various competing widescreen formats.
Current practice
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Eventually, aspect ratios of 1.85:1 in
North America
and 1.66:1 in
Europe
became standard for 35 mm productions shot with normal non-
anamorphic
lenses. However, the way the aspect ratio is created with these films is not in-camera, but rather by placing a cropping device, known as an
aperture mask
, over the film in the projector. What this means is that most films are shot in full screen format (often incorrectly referred to as 1.33:1 but actually 1.37:1 because of the sound tracks), but composed for 1.85:1 or 1.66:1 and cropped that way in projection. Therefore, a fair percentage of the film is wasted, because the cropped top and bottom are usually never meant to be shown, unless it was well protected for full screen presentation.
3-perf and 2-perf are only used in the origination and post-production transfer process.
35 mm
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2-perf
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2-perf camera systems use 2 perforations per frame on 35 mm film with an aspect ratio close to 2.39:1; the aspect ratio used in
anamorphic
prints. It was first proposed conceptually around 1930, but was not put into practice until 1961, when
Techniscope
was developed at
Technicolor
's Italian branch. It has recently been brought up again with the advent of higher quality, lower grain
film stocks
as well as
digital intermediate
post-production methods which eliminate optical blowups and thus improve quality. While in the recent past, some companies have offered custom conversions of camera equipment to 2-perf, it appears that camera manufacturers are now poised to support the format.
Arri
made 2-perf movement blocks for their
Arricam
and
Arriflex 235
cameras available for rental in March 2007.
[1]
Aaton
's
Penelope
camera, released in October 2008, was the first camera specifically designed for 2-perf usage (as well as 3-perf).
3-perf
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In the early 1980s, Swedish cinematographer
Rune Ericson
collaborated with
Panavision
on the concept of creating a 3-perf mechanism for motion picture cameras.
[2]
By changing the camera gate and shutter mechanism, 3-perf minimized the problem of wasted film; each frame is 3 perforations high rather than the standard 4-perforations. The 3-perf image's aspect ratio is roughly 1.78:1, formatted closer to the widescreen television's common aspect of 1.85:1, minimizing image lost outside this aspect. With a smaller frame, the camera effectively runs 25% slower, yielding 25% savings on film stock; the camera will run more quietly because less film is moved through the camera per frame; and the
Super 35
variant allows for a larger negative area, which can help compensate for increased grain when using higher-speed film stocks.
In the late 1990s, cinematographer
Vittorio Storaro
proposed a film standard known as
Univisium
(also called Univision), which advocated for 3-perf Super 35 to create a 2.00:1 aspect ratio.
Disadvantages of 3-perf and 2-perf
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One disadvantage of 3-perf and 2-perf is found when projected theatrically, as it needs to be transferred back to a 4-perf system. This typically involves a
film print
with black cropping on the print itself in order to fit the image onto a 4-perf frame ? encountering the same wastage problem as before. Even so, the amount of film shot on a production is much greater than the length of the final film, so 3-perf or 2-perf are still viable cost-saving options for production. Generally, 3-perf is most frequently used for
widescreen
television productions shot on film, as film is developed and then transferred to
video
, rendering projection incompatibilities irrelevant. Recently, this process has become popular with big-budget motion picture production, due to the advent of the
digital intermediate
process. The negative is scanned to high resolution (usually HD, 2K or 4K (
digital cinema
)) digital files, colour graded, and ultimately printed back to standard 4-perf for projection. At some point in the future, the final 4-perf print will become unnecessary assuming the cinema distribution and projection chain become fully digital.
3-perf and 2-perf pose minor problems for visual effects work. The area of the film in 4-perf work that is not projected nonetheless contains picture information which is useful for such visual effects tasks as 2D and 3D tracking.
[
citation needed
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This mildly complicates certain visual effects efforts for productions using 3-perf and 2-perf.
A VistaVision 35 mm horizontal camera film frame. The dotted area shows the area actually used.
VistaVision
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VistaVision
is a higher resolution,
widescreen
variant of the
35 mm motion picture film
format which was created by
Paramount Pictures
in 1954. It uses a horizontal, 8 perforation 35 mm image, similar to that used in
135 film
for
still photography
. Paramount did not use
anamorphic
processes such as
CinemaScope
but refined the quality of their flat widescreen system by orienting the 35 mm negative horizontally in the camera gate and shooting onto a larger area, which yielded a finer-grained projection print.
70 mm
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Standard 65 mm (5/70) (Todd-AO, Super Panavision)
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- spherical lenses
- 5 perforations/frame
- 42 frames/meter (12.8 frame/ft)
- 34.29 meters/minute (112.5 ft/minute)
- vertical pulldown
- 24 frames/second
- camera aperture
: 52.48 by 23.01 mm (2.066 by 0.906 in)
- projection aperture
: 48.56 by 20.73 mm (1.912 by 0.816 in)
- 305 m (1000 feet), about 9 minutes at 24 frame/s = 4.5 kg (10 pounds) in can
- aspect ratio
: 2.2:1
Ultra Panavision 70 (MGM Camera 65)
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Same as Standard 65 mm except
- Shot with special anamorphic adapter in front of lens
- 1.25× squeeze factor, projected aspect ratio 2.76:1
Showscan
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Same as Standard 65 mm except
IMAX (15/70)
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- spherical lenses
- 15 perforations per frame
- horizontal movement, from right to left (viewed from base side)
- 24 frames per second
- camera aperture
: 70.41 by 52.63 mm (2.772 by 2.072 in)
- projection aperture
: at least 2 mm (0.080 in) less than camera aperture on the vertical axis and at least 0.4 mm (0.016 in) less on the horizontal axis
- aspect ratio
: 1.35:1 (camera), 1.43:1 (projected)
Dynavision (8/70) (Also known as Iwerks 8/70)
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- fisheye or spherical lenses, depending on if projecting for a dome or not
- vertical pulldown
- 24 or 30 frames per second
- camera aperture
: 52.83 by 37.59 mm (2.080 by 1.480 in)
See also
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References
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- ^
Arri advertisement,
British Cinematographer
, March 2007, p. 2.
- ^
"Rune Ericson biography"
.
The Swedish Film Database
. Retrieved
2016-09-20
.
External links
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