Movie Projectors

Movie projectors

A movie projector is an opto-mechanical device for displaying moving pictures by projecting them on a projection screen. Most of the optical and mechanical elements, except for the illumination and sound devices, are present in movie cameras.

Camera Obscura

The camera obscura is an optical device that projects an image of its surroundings on a screen. It is used in drawing and for entertainment, and was one of the inventions that led to photography. The device consists of a box or room with a hole in one side. Light from an external scene passes through the hole and strikes a surface inside where it is reproduced, upside-down, but with colour and perspective preserved. The image can be projected onto paper, and can then be traced to produce a highly accurate representation.

Using mirrors, as in the 18th century overhead version, it is possible to project a right-side-up image. Another more portable type is a box with an angled mirror projecting onto tracing paper placed on the glass top, the image being upright as viewed from the back.

As a pinhole is made smaller, the image gets sharper, but the projected image becomes dimmer. With too small a pinhole the sharpness again becomes worse due to diffraction. Some practical camera obscuras use a lens rather than a pinhole because it allows a larger aperture, giving a usable brightness while maintaining focus.

Magic Lantern

The magic lantern has a concave mirror behind a light source that gathers light and projects it through a slide with an image painted onto it. The light rays cross an aperture (which is an opening at the front of the apparatus), and hits a lens. The lens throws an enlarged picture of the original image from the slide onto a screen. Main light sources used during the time it was invented in the late 1600s were candles or oil lamps. These light sources were quite inefficient and produced weak projections. The invention of the Argand lamp in the 1780s helped to make the projected images brighter. The invention of the limelight in the 1820s made it even brighter, and following that the inventions of the electric arc lamp in the 1850s, and then incandescent electric lamps all further improved the projected image of the magic lantern. It was also an important invention for the motion picture film and 35mm projector because of its ability to screen moving images. To achieve this, mechanical slides were used to make the images move. This was done using two glass slides, one with the part of the picture that would remain stationary and one with the part of the picture that would move on a disc. The glass slides were placed one on top of the other and a hand-operated pulley wheel was used to turn the movable disc. The magic lantern also led directly to Eadweard Muybridge’s invention of the zoopraxiscope, which was another forerunner for moving pictures.

Types of projectors

Projectors are classified by the size of the film used, i.e. the film format. Typical film sizes:

8 mm

Long used for home movies before the video camera, this uses double sprocketed 16 mm film, which is run through the camera twice. The 16 mm film is then split lengthwise into two 8 mm pieces that

Super 8mm

Developed by Kodak, this film stock uses very small sprocket holes close to the edge that allow more of the film stock to be used for the images. This increases the quality of the image. The unexposed film is supplied in the 8 mm width, not split during processing as is the earlier 8 mm. Magnetic stripes could be added to carry encoded sound to be added after film development.

9.5 mm

Film format introduced by Pathé Frères in 1922 as part of the Pathé Baby amateur film system. It was conceived initially as an inexpensive format to provide copies of commercially-made films to home users. The format uses a single, central perforation (sprocket hole) between each pair of frames, as opposed to 8 mm film which has perforations along one edge, and most other film formats which have perforations on each side of the image. It became very popular in Europe over the next few decades and is still used by a small number of enthusiasts today. Over 300,000 projectors were produced and sold mainly in France and England, and many commercial features were available in the format. In the sixties the last projectors of this format were being produced.

16 mm

This was a popular format for audio-visual use in schools and as a high-end home entertainment system before the advent of broadcast television. The most popular home content were comedic shorts (typically less than 20 minutes in length in the original release) and bundles of cartoons previously seen in movie theaters. 16 mm enjoys widespread use today as a format for short films, independent features and music videos, being a relatively economical alternative to 35 mm.

35 mm

35 mm film is typically run vertically through the camera and projector. In the mid 1950's the VistaVision system presented wide screen movies in which the film moved horizontally, allowing much more film to be used for the image as this avoided the anamorphic reduction of the image to fit the frame width. As this required specific projectors it was largely unsuccessful as a presentation method while remaining attractive as filming, intermediate, and source for production printing and as an intermediate step in special effects to avoid film granularity, although the latter is now supplanted by digital methods.

70 mm

High end movie productions were often produced in this film gauge in the 1950s and 1960s and many very large screen theaters are still capable of projecting it in the 21st century. It is often referred to as 65/70, as the camera uses film 65 mm wide, but the projection prints are 70 mm wide. The extra five millimeters of film accommodated the soundtrack, usually a six track magnetic stripe. The most common theater installation would use dual gauge 35/70mm projectors.

The advent of 35 mm prints with digital soundtracks in the 1990s largely supplanted the widespread release of the more expensive 70 mm prints.

IMAX

IMAX is a motion picture film format and projection standard created by the Canadian IMAX Corporation.

IMAX has the capacity to record and display images of far greater size and resolution than most conventional film systems. A standard IMAX screen is 22 × 16.1 m (72 × 52.8 ft) and they are generally the same everywhere. IMAX theatres are described as either "Classic Design," (Purpose-built structures designed to house an IMAX theatre) or "Multiplex Design." The world's largest cinema screen (and IMAX screen) is in the LG IMAX theatre in Sydney, New South Wales. It is approximately 8 stories high, with dimensions of 35.73 × 29.42 m (117.2 × 96.5 ft) and covers an area of more than 1,015 m2 (10,930 sq ft).

IMAX is the most widely used system for special-venue film presentations. As of December 2009, there were more than 400 IMAX theatres in over 40 countries. Imax Corporation has released four projector types that use its 15-perforation, 70mm film format: GT (Grand Theatre), GT 3D (dual rotor), SR (Small Rotor), and MPX, which was designed to be retrofitted in existing multiplex theatres. In July 2008, the company introduced a digital projection system, which it has not given a distinct name or brand, designed for multiplex theatres with screens no wider than 21.3 m (70 ft). A presentation that is digitally projected is nonetheless represented to be IMAX, contrary to the extent of trademarks registered with the U.S. Patent and Trademark Office.

All IMAX projectors, except the standard GT system, can project 3D images.

Most IMAX theatres have flat, rectangular screens, but IMAX Dome theatres, formerly branded as OMNIMAX, use a GT projector with a fish-eye lens to project an image on a tilted hemispheric dome screen. IMAX also has a special simulator technique which uses seat movement/vibration at specific points in the film.

Prasad IMAX theater hyderabad

IMAX BIG cinemas (formerly Adlabs) in Wadala, Mumbai

- the world's largest IMAX Dome theatre

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