Year book of motion pictures (1929)

adjustment for either overhead or side lighting : (35). A high-intensity arc lamp is said to produce steadiness in illumination by having an automatic arc control. The lamp operates at 50 amperes on a 110-volt circuit. The negative carbon passes through the mirror and the positive carbon feed is controlled by a gear shift at the rear of the lamp housing: (36). The Weinert Studio Arc Lamps can be made to take current ranging from 15 to 500 amperes and effectively utilize a potential difference of 160 volts at the carbon tips when running on a 200volt circuit. The three-phase sunlight lamp has three separate carbons which feed toward each other at an equal angle of 120°. The small enclosed arc lamps give satisfactory results on d-c or a-c while the larger arcs run on a-c only: (37). The quartz-mercury lamp and the incandescent lamp are given particular attention in an article on the spectral composition of various types of light sources in relation to photographic sensitivity: (38). A general review of the use of Mazda lamps for photography has been made. The principles of photographic lighting are discussed, and illustrated examples of portrait and commercial photography are given. The spectral sensitivity of photographic materials and >he control of lighting, are briefly but well treated: (39). A complete survey of recent figures in the illuminating art has been made by the Illuminating "Engineering Society. There are over 600 references included with brief notes on the contents of the articles: (40). A second edition of a bulletin "Mazda Lamps in Photography," has been issued by the Harrison works of the General Electric Co. Typical illustrations of use in modern studios, commerce, and home photography are given: (41). Under the title "Artificial Light Sources for Cine Talking," a complete discussion is made of the various types of illumination units available for motion picture studio lighting: (42). In the early part of a paper on "Lighting by Tungsten Filament Incandescent Electric Lamps for Motion Picture Photography," the author discusses the requirements of studio lighting and draws attention to the advantage of using tungsten lamps for this purpose. The latter part of the paper is devoted to a careful analysis of costs involved in the use of various elements such as tungsten lamps, mercury vapor, arcs, high intensity arcs, and ordinary hard-cored carbon arcs. These cost analyses are worked out for ordinary orthochromatic and panchromatic films: (43). In "Lighting and the Cameraman," the great importance of light in producing the desired picture quality is emphasized. Many illustrations are given showing the application of light in the studio for obtaining the desired effect: (44). Some interesting data has been obtained in a careful investigation of the characteristics of the quartz mercury arc under different voltages, current densities and internal tube diameter. The total efficiency as the ratio of radiant power to electrical input increases with increasing arc voltage, current density and tube diameter. Under ' given electrical conditions the efficiency can be increased by heating the luminous tube: (45). Laboratory Equipment and Apparatus A new machine for developing motion picture negatives is claimed to bring about absolutely uniform development. An automatic control of the rollers insures absolutely even tension of the film at all times, hence obviating film breakage trouble : (46). A bright safelight for panchromatic development has three windows of increasing brightness, green Virida paper comprising the light filters. The light is so arranged over the developing trays that no direct light strikes the trays and yet the room is illuminated sufficiently to make working conditions very comfortable: (47). The most satisfactory method of removing excess moisture from motion picture film after washing is to impinge a blast of air on both sides of the film. An apparatus is described for blowing the water from the film as the film is passed from the rack to the drying reel. A special filter for removing dirt and oil from the air supply is also described: (48). A simple equipment for the determination of shutter speeds in automatic type motion picture cameras is described as consisting of a cylinder mounted on the turntable of a phonograph and the camera with its back removed is placed in such a position that a lamp filament is focused through the camera lens onto the cylinder. Film is wound on the cylinder and the light exposed for one second. To compute the speed, the width of the average exposure record and its reciprocal are multiplied by x/120 where x is the number of filaments seen in each exposure if the lamp is fed from a 60-cycle a-c circuit: (49). Lenses One author states that perspective in motion pictures is usually unnatural due to the use of objectives of too short focal length. An objective of 250 mm. focal length would give a picture with normal perspective: (50). In a discussion of the photography of objects in motion in miniature sets. formulas are given for computing the speed of motion of objects or camera speed to accord with the use of miniatures made to different scales. Telephoto lenses are recommended for securing satisfactory depth of focus : (51). Motion Picture Applicants An automatic apparatus for taking single photographic exposures at regular intervals of time, over periods of from 12 to 36 hours, consists of a large air thermostat and a clock mechanism, and is used to make microscopic or ultra-microscopic investigation of clays or other colloidal material: (52). "The Use of Motion Pictures for Governmental Purpose" describes the way in which motion picture film has been used and may be used by national governments for purposes of propaganda. The use of films by the Canadian Government is described in detail: (53). Under the title "Motion Photomicrography," the author discusses the use of a microscope with the motion picture camera to obtain photographs of very small objects. The equipment required and the magnifications suitable for various types of work are discussed. For relatively low power work, the author uses a microscope of the ordinary form or a single lens of suitable focal length. For higher power work he recommends the use of the supermicroscope which is a form of a double compound instrument. The use of an ocular provided with a beam splitting device, so that the field can be viewed while taking, is also recommended: (54). A Berlin surgeon has patented an apparatus for taking motion pictures of surgical operations, which fulfills the conditions for asepsis, does not require a harmful lighting, and takes a view that portrays the details. The camera is suspended from the ceiling and controlled by motors, which are outside the room: (55). Nature Studies One of the notable wild life pictures of the year was taken entirely without the aid of trick photography: (56). One of the greatest photographic hunts yielded 200,000 ft. of film and 7,000 stills. The films will be presented to the American Museum of Natural History: (57). Physiology The final judge of all motion picture efforts, the human eye, has been traced in its development from a simple light-sensitive cell to the more complicated forms : (58). Projection Room Equipment and Apparatus And endless film projector is described in a German magazine. The film lies on radial rollers in a horizontal magazine. It is fed to an ordinary projector from the outside of the roll, and is rewound in the inside: (59). 985