Friday, April 20, 2007
Cinematography 3
Frame rate selection
Main article: Frame rate
Motion picture images are presented to an audience at a constant speed. In the theater it is 24 frames per second, in NTSC (US) Television it is 30 frames per second (29.97 to be exact), in PAL (Europe) television it is 25 frames per second. This speed of presentation does not vary.
However, by varying the speed at which the image is captured, various effects can be created knowing that the faster or slower recorded image will be played at a constant speed.
For instance, time-lapse photography is created by exposing an image at an extremely slow rate. If a cinematographer sets a camera to expose one frame every minute for four hours, and then that footage is projected at 24 frames per second, the event that took four hours to record will now take 10 seconds to present (1 frame per minute for 4 hours equals 240 frames, projected at 24 frames per second equals 10 seconds). This compresses the event that took place in four hours into just 10 seconds. At this speed, one can present the events of a whole day (24 hours) in just one minute. The inverse of this, if an image is captured at speeds above that at which they will be presented, the effect is to greatly slow down (slow motion) the image. If a cinematographer shoots a person diving into a pool at 96 frames per second, and that image is presented back at 24 frames per second, it will take 4 times as long to watch the dive as it did for it to actually happen. Taken to extremes, capturing many thousands of frames per second can allow visual representation of events normally invisible to the human eye, such as bullets in flight and shockwaves travelling through media, a potentially powerful cinematographical technique.
In motion pictures the manipulation of time and space is a considerable contributing factor to the narrative storytelling tools. Film editingplays a much stronger role in this manipulation, but frame rate selection in the photography of the original action is also a contributing factor to altering time.
Speed ramping, or simply "ramping", is a process whereby the capture frame rate of the camera changes over time. For example, if in the course of 10 seconds of capture, the capture frame rate is adjusted from 60 frames per second to 24 frames per second, when played back at the standard film rate of 24 frames per second, a unique time-manipulation effect is achieved. For example, someone pushing a door open and walking out into the street would appear to start off in slow-motion, but in a few seconds later within the same shot the person would appear to walk in "realtime" (normal speed). The opposite speed-ramping is done in The Matrix when Neo re-enters the Matrix for the first time to see the Oracle. As he comes out of the warehouse "load-point", the camera zooms into Neo at normal speed but as it gets closer to Neo's face, time seems to slow down, perhaps visually accentuating Neo pausing and reflecting a moment, and perhaps alluding to future manipulation of time itself within the Matrix later on in the movie.
ROLE OF CINEMATOGRAPHY
In the film industry, the cinematographer is responsible for the technical aspects of the images (lighting, lens choices, composition, exposure, filtration, film selection), but works closely with the director to ensure that the artistic aesthetics are supporting the director's vision of the story being told. The cinematographers are the heads of the camera, grip and lighting crew on a set, and for this reason they are often called directors of photography or DPs.
Directors of photography make many creative and interpretive decisions during the course of their work, from pre-production to post-production, all of which affect the overall feel and look of the motion picture. Many of these decisions are similar to what a photographerneeds to note when taking a picture: the cinematographer controls the film choice itself (from a range of available stocks with varying sensitivities to light and color), the selection of lens focal lengths, aperture exposure and focus. Cinematography, however, has a temporal aspect (see persistence of vision), unlike still photography, which is purely a single still image. It is also bulkier and more strenuous to deal with movie cameras, and it involves a more complex array of choices. As such a cinematographer often needs to work co-operatively with more people than does a photographer, who could frequently function as a single person. As a result, the cinematographer's job also includes personnel management and logistical organization.
Sunday, April 15, 2007
Cinematography 2
Lens
Lenses can be attached to the camera to give a certain look, feel, or effect by focus, color, etc.
As does the human eye, the camera creates perspective and spatial relations with the rest of the world. However, unlike one's eye, a cinematographer can select different lenses for different purposes. Variation in focal length is one of the chief benefits. The focal length of the lens determines the angle of view and, therefore, the field of view. Cinematographers can choose from a range of wide angle lenses, "normal" lenses and telephoto lenses, as well as macro lenses and other special effect lens systems such as borescope lenses. Wide-angle lenses have short focal lengths and make spatial distances more obvious. A person in the distance is shown as much smaller while someone in the front will loom large. On the other hand, telephoto lenses reduce such exaggerations, depicting far-off objects as seemingly close together and flattening perspective. The differences between the perspective rendering is actually not due to the focal length by itself, but by the distance between the subjects and the camera. Therefore, the use of different focal lengths in combination with different camera to subject distances creates these different rendering. Changing the focal length only while keeping the same camera position doesn't affect perspective but the angle of view only. A Zoom lens allows a camera operator to change their focal length within a shot or quickly between setups for shots. As prime lenses offer greater optical quality and are "faster" (larger aperture openings, usable in less light) than zoom lenses, they are often employed in professional cinematography over zoom lenses. Certain scenes or even types of filmmaking, however, may require the use of zooms for speed or ease of use, as well as shots involving a zoom move.
As in other photography, the control of the exposed image is done in the lens with the control of the diaphragm aperture. For proper selection, the cinematographer needs that all lenses be engraved with T-Stop, not f-stop, so that the eventual light loss due to the glass doesn't affect the exposure control when setting it using the usual meters. The choice of the aperture also affects image quality (aberrations) and depth of field (see below).
Depth of field and focus
Focal length and diaphragm aperture affect the depth of field of a scene — that is, how much the background, mid-ground and foreground will be rendered in "acceptable focus" (only one exact plane of the image is in precise focus) on the film or video target. Depth of field (not to be confused with depth of focus) is determined by the aperture size and the focal distance. A large or deep depth of field is generated with a very small iris aperture and focusing on a point in the distance, whereas a shallow depth of field will be achieved with a large (open) iris aperture and focusing closer to the lens. Depth of field is also governed by the format size. 70 mm film has much more depth of field for the same focal length lens than does 35 mm. 16 mm has even less and most digital video cameras have less depth of field than 16 mm. But if one considers the field of view and angle of view, the smaller the image is, the shorter the focal length should be, as to keep the same field of view. Then, the smaller the image is, the more depth of field is obtained, for the same field of view. Therefore, 70mm has less depth of field than 35mm for a given field of view, 16mm more than 35mm, and video cameras even more depth of field than 16mm. As videographers try to emulate the look of 35 mm film with digital cameras, this is one issue of frustration - excessive depth of field with digital cameras and using additional optical devices to reduce that depth of field.
In Citizen Kane (1941), cinematographer Gregg Toland and director Orson Welles used tighter apertures to create very large depth of field in the scenes, often rendering every detail of the foreground and background of the sets in sharp focus. This practice is known as deep focus. Deep focus became a popular cinematographic device from the 1940s onwards in Hollywood. Today, the trend is for more shallow focus.
To change the plane of focus from one object or character to another within a shot is commonly known as a rack focus.
Aspect ratio and framing
The aspect ratio of an image is the ratio of its width to its height. This can be expressed either as a ratio of 2 integers, such as 4:3, or in a decimal format, such as 1.33:1 or simply 1.33.
Different ratios provide different aesthetic effects. Standards for aspect ratio have varied significantly over time.
During the silent era, aspect ratios varied widely, from square 1:1, all the way up to the extreme widescreen 4:1 Polyvision. However, from the 1910s, silent motion pictures generally settled on the ratio of 4:3 (1.33). The introduction of sound-on-film briefly narrowed the aspect ratio, to allow room for a sound stripe. In 1932 a new standard was introduced, the Academy ratio of 1.37, by means of thickening theframe line.
For years, mainstream cinematographers were limited to using the Academy ratio, but in the 1950s, thanks to the popularity of Cinerama,widescreen ratios were introduced in an effort to pull audiences back into the theater and away from their home television sets. These new widescreen formats provided cinematographers a wider frame within which to compose their images.
Many different proprietary photographic systems were invented and utilized in the 1950s to create widescreen movies, but one dominates film today: the anamorphic process, which optically squeezes the image to photograph twice the horizontal area to the same size vertical as standard "spherical" lenses.
The first commonly used anamorphic format was CinemaScope, which used a 2.35 aspect ratio, although it was originally 2.55. CinemaScope was used from 1953 to 1967, but due to technical flaws in the design and its ownership by Fox, several third-party companies, led by Panavision's technical improvements in the 1950s, now dominate the anamorphic cine lens market.
Changes to SMPTE projection standards altered the projected ratio from 2.35 to 2.39 in 1970, although this did not change anything regarding the photographic anamorphic standards; all changes in respect to the aspect ratio of anamorphic 35 mm photography are specific to camera or projector gate sizes, not the optical system.
After the "widescreen wars" of the 1950s, the motion-picture industry settled into 1.85 as a standard for theatrical projection in the United States and the United Kingdom. This is a cropped version of 1.37. Europe and Asia opted for 1.66 at first, although 1.85 has largely permeated these markets in recent decades. Certain "epic" or adventure movies utilized the anamorphic 2.39.
In the 1990s, with the advent of high-definition video, television engineers created the 1.78 (16:9) ratio as a mathematical compromise between the theatrical standard of 1.85 and television's 1.33, as it was not practical to produce a traditional CRT television tube with a width of 1.85. Until that point, nothing had ever been originated in 1.78. Today, this is a standard for high-definition video and for widescreen television. Some cinema films are now shot using HDTV cameras.
Lighting
Light is necessary to create an image exposure on a frame of film or on a digital target (CCD, etc.). The art of lighting for cinematography goes far beyond basic exposure, however, into the essence of visual storytelling. Lighting contributes considerably to the emotional response an audience has watching a motion picture.
Camera movement
Main article: Cinematic techniques
One aspect of cinematography that strongly separates it from still photography (aside from having a moving subject) is the ability to move the camera, which represents the audience's viewpoint or perspective, during the course of filming. This movement plays a considerable role in the emotional language of film images and the audience's emotional reaction to the action on the screen. Techniques range from the most basic movements of panning (horizontal shift in viewpoint from a fixed position; like turning your head side-to-side) and tilting (vertical shift in viewpoint from a fixed position; like tipping your head back to look at the sky or down to look at the ground) to dollying (placing the camera on a moving platform to move it closer or farther from the subject), tracking (placing the camera on a moving platform to move it to the left or right), craning (moving the camera in a vertical position; being able to lift it off the ground as well as swing it side-to-side from a fixed base position), and combinations of the above.
Cameras have been mounted to nearly every imaginable form of transportation.
Most cameras can also be handheld, that is the camera operator literally holds the camera in their hands and moves from one position to another while filming the action. Personal stabilizing platforms came into being in the late 1970s through the invention of Garrett Brown, which became known as the Steadicam. The Steadicam is a body harness and stabilization arm that connects to the camera that allows the operator to move naturally while completely isolating the movements of their body from the movements of the camera. After the Steadicam patent expired in the early 1990s, many other companies began manufacturing their concept of the personal camera stabilizer.
Lenses can be attached to the camera to give a certain look, feel, or effect by focus, color, etc.
As does the human eye, the camera creates perspective and spatial relations with the rest of the world. However, unlike one's eye, a cinematographer can select different lenses for different purposes. Variation in focal length is one of the chief benefits. The focal length of the lens determines the angle of view and, therefore, the field of view. Cinematographers can choose from a range of wide angle lenses, "normal" lenses and telephoto lenses, as well as macro lenses and other special effect lens systems such as borescope lenses. Wide-angle lenses have short focal lengths and make spatial distances more obvious. A person in the distance is shown as much smaller while someone in the front will loom large. On the other hand, telephoto lenses reduce such exaggerations, depicting far-off objects as seemingly close together and flattening perspective. The differences between the perspective rendering is actually not due to the focal length by itself, but by the distance between the subjects and the camera. Therefore, the use of different focal lengths in combination with different camera to subject distances creates these different rendering. Changing the focal length only while keeping the same camera position doesn't affect perspective but the angle of view only. A Zoom lens allows a camera operator to change their focal length within a shot or quickly between setups for shots. As prime lenses offer greater optical quality and are "faster" (larger aperture openings, usable in less light) than zoom lenses, they are often employed in professional cinematography over zoom lenses. Certain scenes or even types of filmmaking, however, may require the use of zooms for speed or ease of use, as well as shots involving a zoom move.
As in other photography, the control of the exposed image is done in the lens with the control of the diaphragm aperture. For proper selection, the cinematographer needs that all lenses be engraved with T-Stop, not f-stop, so that the eventual light loss due to the glass doesn't affect the exposure control when setting it using the usual meters. The choice of the aperture also affects image quality (aberrations) and depth of field (see below).
Depth of field and focus
Focal length and diaphragm aperture affect the depth of field of a scene — that is, how much the background, mid-ground and foreground will be rendered in "acceptable focus" (only one exact plane of the image is in precise focus) on the film or video target. Depth of field (not to be confused with depth of focus) is determined by the aperture size and the focal distance. A large or deep depth of field is generated with a very small iris aperture and focusing on a point in the distance, whereas a shallow depth of field will be achieved with a large (open) iris aperture and focusing closer to the lens. Depth of field is also governed by the format size. 70 mm film has much more depth of field for the same focal length lens than does 35 mm. 16 mm has even less and most digital video cameras have less depth of field than 16 mm. But if one considers the field of view and angle of view, the smaller the image is, the shorter the focal length should be, as to keep the same field of view. Then, the smaller the image is, the more depth of field is obtained, for the same field of view. Therefore, 70mm has less depth of field than 35mm for a given field of view, 16mm more than 35mm, and video cameras even more depth of field than 16mm. As videographers try to emulate the look of 35 mm film with digital cameras, this is one issue of frustration - excessive depth of field with digital cameras and using additional optical devices to reduce that depth of field.
In Citizen Kane (1941), cinematographer Gregg Toland and director Orson Welles used tighter apertures to create very large depth of field in the scenes, often rendering every detail of the foreground and background of the sets in sharp focus. This practice is known as deep focus. Deep focus became a popular cinematographic device from the 1940s onwards in Hollywood. Today, the trend is for more shallow focus.
To change the plane of focus from one object or character to another within a shot is commonly known as a rack focus.
Aspect ratio and framing
The aspect ratio of an image is the ratio of its width to its height. This can be expressed either as a ratio of 2 integers, such as 4:3, or in a decimal format, such as 1.33:1 or simply 1.33.
Different ratios provide different aesthetic effects. Standards for aspect ratio have varied significantly over time.
During the silent era, aspect ratios varied widely, from square 1:1, all the way up to the extreme widescreen 4:1 Polyvision. However, from the 1910s, silent motion pictures generally settled on the ratio of 4:3 (1.33). The introduction of sound-on-film briefly narrowed the aspect ratio, to allow room for a sound stripe. In 1932 a new standard was introduced, the Academy ratio of 1.37, by means of thickening theframe line.
For years, mainstream cinematographers were limited to using the Academy ratio, but in the 1950s, thanks to the popularity of Cinerama,widescreen ratios were introduced in an effort to pull audiences back into the theater and away from their home television sets. These new widescreen formats provided cinematographers a wider frame within which to compose their images.
Many different proprietary photographic systems were invented and utilized in the 1950s to create widescreen movies, but one dominates film today: the anamorphic process, which optically squeezes the image to photograph twice the horizontal area to the same size vertical as standard "spherical" lenses.
The first commonly used anamorphic format was CinemaScope, which used a 2.35 aspect ratio, although it was originally 2.55. CinemaScope was used from 1953 to 1967, but due to technical flaws in the design and its ownership by Fox, several third-party companies, led by Panavision's technical improvements in the 1950s, now dominate the anamorphic cine lens market.
Changes to SMPTE projection standards altered the projected ratio from 2.35 to 2.39 in 1970, although this did not change anything regarding the photographic anamorphic standards; all changes in respect to the aspect ratio of anamorphic 35 mm photography are specific to camera or projector gate sizes, not the optical system.
After the "widescreen wars" of the 1950s, the motion-picture industry settled into 1.85 as a standard for theatrical projection in the United States and the United Kingdom. This is a cropped version of 1.37. Europe and Asia opted for 1.66 at first, although 1.85 has largely permeated these markets in recent decades. Certain "epic" or adventure movies utilized the anamorphic 2.39.
In the 1990s, with the advent of high-definition video, television engineers created the 1.78 (16:9) ratio as a mathematical compromise between the theatrical standard of 1.85 and television's 1.33, as it was not practical to produce a traditional CRT television tube with a width of 1.85. Until that point, nothing had ever been originated in 1.78. Today, this is a standard for high-definition video and for widescreen television. Some cinema films are now shot using HDTV cameras.
Lighting
Light is necessary to create an image exposure on a frame of film or on a digital target (CCD, etc.). The art of lighting for cinematography goes far beyond basic exposure, however, into the essence of visual storytelling. Lighting contributes considerably to the emotional response an audience has watching a motion picture.
Camera movement
Main article: Cinematic techniques
One aspect of cinematography that strongly separates it from still photography (aside from having a moving subject) is the ability to move the camera, which represents the audience's viewpoint or perspective, during the course of filming. This movement plays a considerable role in the emotional language of film images and the audience's emotional reaction to the action on the screen. Techniques range from the most basic movements of panning (horizontal shift in viewpoint from a fixed position; like turning your head side-to-side) and tilting (vertical shift in viewpoint from a fixed position; like tipping your head back to look at the sky or down to look at the ground) to dollying (placing the camera on a moving platform to move it closer or farther from the subject), tracking (placing the camera on a moving platform to move it to the left or right), craning (moving the camera in a vertical position; being able to lift it off the ground as well as swing it side-to-side from a fixed base position), and combinations of the above.
Cameras have been mounted to nearly every imaginable form of transportation.
Most cameras can also be handheld, that is the camera operator literally holds the camera in their hands and moves from one position to another while filming the action. Personal stabilizing platforms came into being in the late 1970s through the invention of Garrett Brown, which became known as the Steadicam. The Steadicam is a body harness and stabilization arm that connects to the camera that allows the operator to move naturally while completely isolating the movements of their body from the movements of the camera. After the Steadicam patent expired in the early 1990s, many other companies began manufacturing their concept of the personal camera stabilizer.
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