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1954-55 Theatre Catalog, 12th Edition, Page 203 (167)

1954-55 Theatre Catalog, 12th Edition
1954-55 Theatre Catalog
1954-55 Theatre Catalog, 12th Edition, Page 203
Page 203

1954-55 Theatre Catalog, 12th Edition, Page 203

Wide Angle Slide Projector

A Discussion of the Construction Details and Uses

for Recently Developed 3000 Watts Slide Projector

In 1952 the U. S. Patent Ofiice issued U. S. Patent 2586436 for a new extra m'de angle optical system known as GKP Wide Angle Oblique Projector (GKP Trade Mark 266404).

Used in conjunction with a slide projector, it throws a very wide, undistorted image at a short throw. The width of the image is 110 per cent the distance between the slide projector and the screen. This corresponds to an angle of projection greater than 60 degrees.

A new slide projector has been designed to take advantage of the features of that extra wide angle optical system.

BRIEF: A 3000 watts slide projector that incorporates a newly patented optical system which has a 60 degree angle of projection . . . is described . . . The source of light is a 3000 watts incandescent bulb . . . The manufacturer has endeavored to make a slide projector to project images larger and brighter than ever obtained before . . . The slide projector is supplied either with an automatic slide changer for advertising . . . or a manual changer for theatre background projection . . . Details are given on the construction . . . and many indoor and outdoor uses for the projector.

-# The slide projector was made as powerful as possible in order to project images that were brighter and larger than any projected by other slide projectors.

Source of Light

In order to make a slide projector that could operate automatically, without an operator, an incandescent bulb was used in preference to an arc lamp. General Electricls 3000 watts projection lamp model 3MT32 base up is used because of its long life expectancy, its concentrated light, and its large lumens output.

The 3-1/4 inches by 4 inches slide was chosen because it is a standard size and large libraries of commercial slides of that dimension exist, and also because 2 by 2 inch slides would have been too small to withstand the light concentration and heat intensity emitted by a 3000 watts lamp.

Width of Image and Illumination

The following schedule shows the illumination and the width of the image corresponding to various throws: Distance Between

Projector and Screen 10' 20' 40' Width of Image 11' 22' 44' Illumination at Center

of Image in Ft. Candles 60 15 4



President, Conurco. Inc.

Height of Image

The maximum height of the image depends on the angle between the optical axis of the slide projector and the horizontal. In Figure 3 the distance between the projector and the screen is 20 feet and the optical axis makes an angle of 30 degrees with the horizontal. The maximum height that can be obtained with the optical system is approximately 32 feet but as the slides are wider than they are high the height of the image will be in the same proportion 3.25 x 32 feet I 26 feet. The image

could be 22 feet wide and 26 feet high. If this height is too great, it can be reduced by using a paper mask in the slides.

In Figure 4 the throw is also 20 feet but the optical axis is horizontal. The maximum height given by the optical system is 22 feet but due to the rectangular shape of the slide, it is limited to 3.25 x 22 feet, approximately 18 feet.

Image will be approximately 22 feet wide and 18 feet high. Paper mask can limit the height, if desired.

Automatic Slide Changers

The slide projector can be supplied either with an automatic slide changer

FIGURE 1. IS A Photograph of this Genaxco Slide Projector. Model SPJ with cl six slide disk changer. the rectangular shape of the shde. it is limited to 18 leer. The beam is over heads of people.

1 31.1033 box

1954-55 Theatre Catalog, 12th Edition, Page 203