International photographer (Jan-Dec 1941)

TelEvisioN (Continued from page 25) nical phrase employed to indicate that the apparatus of vision has sacrificed some of its reserve capacity for seeing (suffered a decline in activity) as a result of previous activity. It must be carefully distinguished from a physical fatigue. In the latter, consciousness of the fatigue is general, whereas in visual fatigue consciousness of the fatigue is rare and then generally ex ists due to an over-exercise of the function of vision. At such stages, it can be serious enough to cause injury to sight depending on the nature and cause. Motion picture and television observation need not be more fatiguing in a visual sense than many other visual tasks, but their seriousness is due to the pro longed activity involved as well as the surrounding conditions. The accompanying visual fatigue is said to be largely retinal and not muscular. The "redeeming" feature of the task when viewing motion pictures, according to one authority, lies in the use of "far vision." In home television, the vision is not so "far" but fortunately, it is not quite as "near" as when reading a book. In this regard, more information is needed to determine the effect of television observation on visual fatigue due to the distance function alone. The greatest difference in viewing television and motion pictures is in this respect, that most screens in theaters can be assumed to be at a distance of 20 feet or more from the viewer, which for all practical purposes can be considered at infinity, at which point the normal eye is at rest. Whereas, with television, the object can be assumed to be from 6 to 8 feet from the eye, entailing an accommodative action and thus necessitating muscular accomplishments for neither near nor far vision. Visual fatigue has been found to be occasioned by high degrees of contrast either between adjacent areas in the field of vision (even including the border of the screen ) or in time as would be the case due to flicker phenomena, the need to see finer detail, and illumination levels below those associated with "easiest seeing." It is said that the apparatus of vision attempts to compensate for any decreased efficiency and this effort is translated into visual fatigue or even pain and injury to the sight. One authority states that the present theater levels are far too low for "easiest seeing." If this is correct, television, which generally operates with an average screen brightness below that of large theaters, should devise and make experiments on the visual fatigue involved. While the level of theater screen brightness is probably actually below that for "easiest seeing," it is probable that the decreased need for discernment of fine detail— the fact that speech and action tell much of the story — reduces the burden, so that even at the present average level of screen brightness the work involved is not in excess in that for other every-day visual tasks of equal duration. Probably the same is true of television to a lesser degree due to other effects. Experimental evidence would be needed for confirmation. It would be complicated by the possible latitude and resolution of the medium. The resolution of fine detail is limited by visual acuity, which is simply 1 /angular size. Greater brightness is required for greater visual acuity. Maximum sensitivity is reached only when the visual angle is not less than about 4 minutes. Continued use of the eyes to discern detail near the limit of visual acuity or near the limit of the Weber-Fechner fraction for brightness difference results in visual fatigue. Screen surroundings which are less than about 1/100 of the field brightness have been proved to be detrimental, causing visual fatigue. In theaters, a border brightness between 0.05 and 0.2 foot-lambert was most frequently chosen when the observer was permitted to choose this level. In the same tests the screen brilliancy chosen was that corresponding to the order of 30 foot-lamberts if the projector had been operated without film. This would correspond under picture conditions with the lO foot-lambert level generally given for close desk work. Flicker was mentioned as a prominent cause of visual fatigue. Intermittency of illumination was found not to be a serious cause of visual fatigue provided it was not discernible to the vision as "flicker." Some evidence was found that flicker due to frame frequency is still a factor in visual fatigue in the motion picture theater. However, other causes of flicker may be even more serious. One has only to look across the beam from the projector in a darkened theater to see that a series of "shocks" are presented to the eye due to the normal shifting of scenes and motion of objects in each scene. Television and the motion picture may, by careful choice, reduce this considerably but it can hardly eliminate it. It seems certain that as the screen brightness increases, more experimental work could very well be done on visual fatigue. The case of seeing and the effect of flicker may have mutually opposite trends under the influence of increased screen brightness but whether or not visual fatigue could be reduced would seem to require experimental verification. Furthermore, it would seem desirable, if possible, to devise experiments designed to reveal the portion of visual fatigue in any given motion picture or television performance which may be assessed solely to frame frequency. {To be concluded next month ) Intricate Electrical Eqpt. One of the most unusual sets ever constructed for a motion picture has been completed at Universal for use in the studio's new "horror" melodrama, "The Mysterious Doctor R." Elaborate and complete, the set represents a modern electrical research laboratry in which Lionel Atwill, as a half-mad scientist, subjects Lon Chaney, Jr., to experiments attempting to prove a theory that human beings can be controlled by electricity. Replicas of such intricate equipment as an electrostat table, high tension insulators, an atomic bombarder, a control cabinet and an oudin coil were enstructed in the studio's technical department under the supervision of Eric Wybrow, noted electrical expert. Laboratory sequences are calculated to be dramatic high spots of "The Mysterious Doctor R," which is being filmed under the direction of George Waggner. Lillian Russell Collection A large mass of original material dealing with the life, romances and career of Lillian Russell, one of the immortals of the American theatre, soon will find its way into the archives of the Pittsburgh, Pennsylvania public library for future study by interested historians. The material was accumulated by Alice Faye, film star. Included in the collection are numerous theatrical programs, original photographs, shoes worn by Miss Russell, one of her hats, a number of original photographs and a mass of newspaper and magazine clippings. Miss Faye is now completing work in her latest starring vehicle, "Tin Pan Alley',' a musical cavalcade at 20th Century-Fox. CLASSIFIED LARGE QUANTITY OF PROFESSIONAL CAMERAS AVAILABLE. WRITE FOR BARGAIN BOOKLET. BURKE & JAMES, INC., 223 W. MADISON ST., CHICAGO, ILL. WANTED TO BUY FOR CASH CAMERAS AND ACCESSORIES MITCHELL, B. & H., EYEMO, DEBRIE. AKELEY ALSO LABORATORY AND CUTTING ROOM EQUIPMENT CAMERA EQUIPMENT COMPANY 1600 Broadway New York City Tel. Circle 6-5080— Cable : CTNEQUIP BELL & HOWELL, 5 WAY SOUND PRINTER. CAMERA EQUIPMENT COMPANY 1600 Broadway New York City Tel. Circle 6-5080— Cable: CINEQUIP FOR SALE: Combination 16 mm. and 35 mm. optical printer very reasonable. Will accept Bell it Howell 35 mm. camera in exchange. Address Box BD 25. International Photographer, Hollywood. FOR SALE: Like new. H.C.E. "Hollywood" Combination 35 mm. and 16 mm. automatic one-man developing machine. Operating capacity 3000 feet of positive or 1500 feet of negative per hour. Price $1250.00. HOLLYWOOD CAMERA EXCHANGE, 1600 N. Cahuenga Blvd. AKELEY CAMERA No. 113. Pair 2-inch matched lenses Zeiss F.3.5 — 654-inch Cooke F.3.5 lens, four 200-foot magazines, tripod. Case for camera, case for magazines — $550.00. DEBRIE PARVO MODEL L with pilot pins and intermittent pressure plate, automatic dissolve, 50mm Zeiss F.2.7 Debrie tripod, 6 magazines and case. Camera case, Debrie motor — $595.00. METAL DEBRIE PARVO MODEL G. automatic dissolve 50mm Zeiss F.3.5. Tripod, 6 magazines and case. Camera case — $250.00. UNIVERSAL CAMERA with automatic dissolve. 50mm Hansel) .V Lomh F.3.5 lens, three .'110 foot magazines, Pan and tilt tripod — $90.00. MOTION PICTURE CAMERA SUPPLY, INC 723 7th Ave., New York City BRyant 9-7754 28 Intkknational Photograph kr for January. 1941