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1945 Theatre Catalog, 4th Edition, Page 318 (294)

1945 Theatre Catalog, 4th Edition
1945 Theatre Catalog
1945 Theatre Catalog, 4th Edition, Page 318
Page 318

1945 Theatre Catalog, 4th Edition, Page 318




DIAGRAM OF THE OPERATION of the Orthoscope auxiliary lens system, reveals how the light is focused in front of the film. The negative (concave) lens picks up the light from the mirror and places it evenly on the positive (convex) lens, from which it passes through the film with equal brilliance from edge to edge.

name, make of objective lens. With this information the Orthoscope is calculated to fill the above requirements.

The accompanying sketch illustrates how the new Orthosc0pe focuses the light in front of the film. The negative lens has picked up the scattered light from the mirror and has placed it evenly on the positive lens, which, on the Simplex machine, is approximately 2 inches from the film. It might be assumed that the introduction of the two additional elements into the existing light beam would cause a considerable loss of light fr0m reflection, because glass usually loses about 4 percent of light on each surface. Since the new Orthoscope has two elements it would appear that therefore a 16 percent loss of light would result. However, the Orthoscope is specially coated, reducing the 105s of light to only 2 percent.

Now by focusing the light and after picking up a greater amount of the light rays from the light source, and by placing the light so as to completely fill the objective lens, the objective lens is in turn now performing a duty that it was originally designed to perform, but never did with proper success until the Orthoscope lens was brought forth. By filling the objective lens with light, the image changes from a square to a round image on the port hole glass,

FOR THE SIMPLEX E-7, this is the Orthoscope lens holder that has been devised by H and H Optics. Installation is very simple: All that is clone is to remove the spot-sight box and insert the Orthoscope.

thus proving that the objective lens is completely filled with light.

The question of the proper amount of amperage needed to give the best screen results is an argument which has gone on for years amongst projectionists and theatre managers, and one in which the writer does not wish to become involved. However, an experience which may be cited is that of the Four Star Theatre in Los Angeles, California, a Fox West Coast first-run theatre. Their equipment consists of a Peerless Magnarc lamp, Super-Simplex machines with Bausch and LOmb Super Cinephor f/2.0 coated objective lenses and the new Orthoscope. The size of the picture is 211/2 feet, with a 105 foot throw. Before installing the new Orthoscope lenses they were using 68 amperes with 7-8 carbons. Now they are using 6-7 carbons, using 42 amperes. The results are a brilliant, pleasing picure. The above illustration would indicate that it is not what amount of amperage is used so much as how it is used that counts.

These are some of the things the theatre gains by installing the new Orthoscope lenses. The screen is filled with more light from corner to corner, a bluish white light achieved by the removal of the chromatic aberration. This improves the black and white picture greatly, but the most noticeable improvement is realized in the showing of colored pictures. The true colors stand out as if they were hand-painted. The audience can view the picture from any seat in the theatre with pleasing results, since distortion has been reduced to a minimum, the picture shows a great depth of focus, which gives a third dimensional eEect, making the characters seem alive.


The transparency of very thin sections of stainless steel has solved one of the serious problems in aerial reconnaissance and mapemaking.

For certain types of aerial photograa phy, cameras are equipped with wideangle lenses, a battery of three such cameras making possible the photogra LENS


To reduce the loss from reflection that four normal air-to-glass surfaces would introduce into the optical system, the two Orthoscope lenses have been given low-reflection coatings, which lets pass approximately 98 per cent of the incident light. Comparison before and after using the Orthoscope lens is very pronounced.

phy of all terrain from horizon to horizon. An inherent property of such wideangle lenses is the "hot spot" in the center of the field, which resulted in pictures which were bright in the center but dark at the edges.

To correct this fault, engineers of the Bausch and Lomb Optical Company developed a vignetting filter, to be installed in front of the lens. This filter consists of a disc of optical glass on which a film of stainless steel is deposited by a special electrovacuum process, not unlike that employed in coating lenses. The film is thickest, and transmits the least light, at the center of the disc; it becomes gradually thinner and more transparent toward the edge; thus it eliminates the hot spot. By complementing the charace teristics of the photographic lens with which it is used, the vignetting filter permits photographs of the ordinary density distribution.

While this vignetting filter could be used in conjunction with a projection lens, if that lens yielded a hot spot on the screen, Bausch and Lomb does not find it necessary in either its Cinephor or Super Cinephor projection lenses. These are designed to produce uniform illumination of the entire screen so that the filter would not have much use. If however, exhibitors do have difficulty with lenses which do create hot spots,


Orthoscope lens holder has been designed. The auxiliary system is tailor-made to eVery theatre's oWn requirements. National Theatre Supply is the seller.

1945 Theatre Catalog, 4th Edition, Page 318