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In film terminology, throw is the distance between a movie projector lens and its screen. It is the distance the image is thrown onto the screen, and it has a large effect on screen size.[ further explanation needed ] Home theatre installations may often have an incorrect[ further explanation needed ] throw distance in the room but this can be corrected by use of a short throw lens. There are also "long throw" lenses available.
A movie projector is an opto-mechanical device for displaying motion picture film by projecting it onto a screen. Most of the optical and mechanical elements, except for the illumination and sound devices, are present in movie cameras.
Home cinema, also called a home theater, a home theatre, and a theater room, are home entertainment audio-visual systems that seek to reproduce a movie theater experience and mood using consumer electronics-grade video and audio equipment that is set up in a room or backyard of a private home. In the 1980s, home cinemas typically consisted of a movie pre-recorded on a LaserDisc or VHS tape; a LaserDisc or VHS player; and a heavy, bulky large-screen cathode ray tube TV set. In the 2000s, technological innovations in sound systems, video player equipment and TV screens and video projectors have changed the equipment used in home theatre set-ups and enabled home users to experience a higher-resolution screen image, improved sound quality and components that offer users more options. The development of Internet-based subscription services means that 2016-era home theatre users do not have to commute to a video rental store as was common in the 1980s and 1990s.
A related measurement, throw ratio, is the ratio of the distance from the lens to the screen (throw) to the screen width. A larger throw ratio corresponds to a more tightly focused optical system.
Throw Ratio = D / W
Depth of field is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image. The depth of field is determined by focal length, distance to subject, the acceptable circle of confusion size, and aperture. A particular depth of field may be chosen for technical or artistic purposes. Some post-processing methods, such as focus stacking allow extended depth of field that would be impossible with traditional techniques.
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (elements), usually arranged along a common axis. Lenses are made from materials such as glass or plastic, and are ground and polished or molded to a desired shape. A lens can focus light to form an image, unlike a prism, which refracts light without focusing. Devices that similarly focus or disperse waves and radiation other than visible light are also called lenses, such as microwave lenses, electron lenses, acoustic lenses, or explosive lenses.
Widescreen images are images that are displayed within a set of aspect ratios used in film, television and computer screens. In film, a widescreen film is any film image with a width-to-height aspect ratio greater than the standard 1.37:1 Academy aspect ratio provided by 35mm film.
VistaVision is a higher resolution, widescreen variant of the 35 mm motion picture film format which was created by engineers at Paramount Pictures in 1954.
The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated (parallel) rays are brought to a focus. A system with a shorter focal length has greater optical power than one with a long focal length; that is, it bends the rays more sharply, bringing them to a focus in a shorter distance.
The f-number of an optical system is the ratio of the system's focal length to the diameter of the entrance pupil. It is a dimensionless number that is a quantitative measure of lens speed, and an important concept in photography. It is also known as the focal ratio, f-ratio, or f-stop. It is the reciprocal of the relative aperture. The f-number is commonly indicated using a hooked f with the format f/N, where N is the f-number.
In optics, a circle of confusion is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. It is also known as disk of confusion, circle of indistinctness, blur circle, or blur spot.
In photography and cinematography, depth compression and expansion with shorter or longer focal lengths introduces noticeable, and sometimes disturbing, distortion while a normal lens is a lens that reproduces a field of view that appears "natural" to a human observer.
CinemaScope is an anamorphic lens series used, from 1953 to 1967, and less often later, for shooting widescreen movies that, crucially, could be screened in theatres using existing equipment, albeit with a lens adapter. Its creation in 1953 by Spyros P. Skouras, the president of 20th Century Fox, marked the beginning of the modern anamorphic format in both principal photography and movie projection.
An overhead projector (OHP) is a variant of slide projector that is used to display images to an audience..
Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a calculated number also called "magnification". When this number is less than one, it refers to a reduction in size, sometimes called minification or de-magnification.
A magnifying glass is a convex lens that is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle. A magnifying glass can be used to focus light, such as to concentrate the sun's radiation to create a hot spot at the focus for fire starting.
An enlarger is a specialized transparency projector used to produce photographic prints from film or glass negatives, or from transparencies.
In optics and photography, hyperfocal distance is a distance beyond which all objects can be brought into an "acceptable" focus. As the hyperfocal distance is the focus distance giving the maximum depth of field, it is the most desirable distance to set the focus of a fixed-focus camera. The hyperfocal distance is entirely dependent upon what level of sharpness is considered to be acceptable.
Macro photography, is extreme close-up photography, usually of very small subjects and living organisms like insects, in which the size of the subject in the photograph is greater than life size . By the original definition, a macro photograph is one in which the size of the subject on the negative or image sensor is life size or greater. However, in some uses it refers to a finished photograph of a subject at greater than life size.
Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image or focus on an object as its distance varies. In this, distances vary for individuals from the far point—the maximum distance from the eye for which a clear image of an object can be seen, to the near point—the minimum distance for a clear image.
Technirama is a screen process that has been used by some film production houses as an alternative to CinemaScope. It was first used in 1957 but fell into disuse in the mid-1960s. The process was invented by Technicolor and is an anamorphic process with a screen ratio the same as revised CinemaScope (2.35:1), but it's actually 2.25:1 on the negative.
In the field of photography, a manual focus camera is one in which the user has to adjust the focus of the lens by hand. Before the advent of autofocus, all cameras had manually adjusted focusing; thus, the term is a retronym.
Anamorphic format is the cinematography technique of shooting a widescreen picture on standard 35 mm film or other visual recording media with a non-widescreen native aspect ratio. It also refers to the projection format in which a distorted image is "stretched" by an anamorphic projection lens to recreate the original aspect ratio on the viewing screen. The word anamorphic and its derivatives stem from the Greek words meaning "formed again". As a camera format, anamorphic format is losing popularity in comparison to "flat" formats such as Super 35 mm film shot using spherical lenses; however, because most film movie projectors use anamorphic projection format, spherical format negatives are commonly converted into anamorphic prints for projection.
In photography, the 35 mm equivalent focal length is a measure that indicates the angle of view of a particular combination of a camera lens and film or sensor size. The term is useful because most photographers experienced with interchangeable lenses are most familiar with the 35 mm film format.