International projectionist (Jan-Dec 1947)

, SPHERICAL /REFLECTOR OPTICAL AXIS ^NEOF ) ,E fohk PARABOLA ^/REFLECTOR PARALLEL RAYS Or . ,-ML AXIS SINGLE^ FOCUS B PARALLEL RAYS FIGURE 2 springs to hold the glass elements in such way that the springs accommodate the expansion and at the same time hold the elements in correct orientation. So much for the glass. With respect to the surfaces of reflectors and condensers certain departures from true curvature are permissible. If the same broad tolerance were allowed for the surfaces of projection lenses, the projected image would be highly distorted and blurred. In fact, the surfaces of reflectors and condensers are not polished on the spindle: they are cast. The method of casting allows the shaping of surfaces different from the spherical. All ground and polished lenses used in projection, for photography and for instruments in general have spherical surfaces. In fact, it is impossible to polish mechanically a surface other than spherical. Lenses and reflectors with non-spherical surfaces for visual or photographic purposes are also made, but these surfaces must be individually polished by hand and the operation requires quite a long time. By casting into a parabolic polished pattern we obtain a parabolic reflector. Even if the pattern be absolutely perfect when cold, when the molten glass is poured into it the shape of the pattern changes. And even if the shape of the pattern should not change but remain true, the glass casting itself would change during the cooling process. Fortunately, as previously mentioned, the surfaces of reflectors and condensers do not have to be absolutely true in order to perform well: therefore they are cast in shapes different from the spherical (parabolic, elliptical) for the already mentioned purpose of eliminating aberrations. At the same time speeds of the order of /:2 and better are obtained. Some readers may wonder why reflector and condenser systems are not corrected for achromatism. The answer is that it is not necessary. Since the reflecting surface is at the front, reflectors cannot split the white light into elementary colors, because the light does not enter into the glass but is reflected by the mirror coating. In all other cases (rear-surface reflector and condenser systems) the rays emanating from the light source do not form a "sharp focus" on the aperture: the focii of the different colors all co-exist in the small space around the aperture and, therefore, from their mixture white light is formed again. Although it is seldom done, optical considerations show that for the most efficient utilization of light the condenser should focus the image of the source of light not on the aperture but on the "second principal plane" of the projection objective— which means at a point slightly inside from the rear element of the objective lens. 25-30 Club Installs Officers, Confers Life Memberships TALL doings transpired in Manhattan projection circles the evening of January 9 when the famed 25-30 Club of New York installed its officers for 1947 and thus provided the setting for the granting of honorary life gold membership cards to deserving workers in the amusement vineyard. Scene of the festivities was the Headquarters Restaurant, directed by the former head service man and chief chef of General Eisenhower's G.H.Q. in Europe. Retiring officers of the Club, both of whom have served for the past seven years, were Mike Berkowitz and Henry Weinberger, each of whom was presented a gold life membership card. The 1947 official slate is comprised of Morris Rotker, president; Cecil R. Wood, Sr., vicepresident; Joseph Fitterman, financial secretary; Morris Klapholz, recording secretary; Albert A. Kaye, sgt.-at-arms. Trustees are Joe Abrams, Dave Narcey, and William Salke. Honorary gold membership cards were presented to Gene Atkinson, business manager of Chicago I. A. Local 110 and I. A. delegate to the A. F. of L. ; Walter E. Green, president of National Theatre Supply Co. and vice-president of General Precision Machine Corp.; M. D. O'Brien, assistant director of projection and sound for Loew's theatres; Major Leslie E. Thompson of R.K.O. Theatres Corp., and Charles Vencill, secretary of Los Angeles I. A. Local 150 and president of the National Conference of Union Labor Legionnaires, Inc. Messrs. Atkinson and Vencill were awarded their cards in absentia, although both marked their election by lengthy telegrams received at the party. Toast master Harry Sherman, of I. P., made personal acknowledgment on behalf of each. Particularly appropriate was the choice of tenders of the honorary cards to the three recipients present. Walter Green received his card from an old friend and business associate for many years, Cecil Wood, Sr., veteran projectionist who by virtue of his extensive Walter E. Green M. D. O'Brien road tours is known to thousands of brother craftsmen throughout the country. M. D. O'Brien was tendered his card by his long-time co-worker, Lester B. Isaac, director of sound and projection for Loew's theatres. Major Thompson, who handles labor contract matters for R.K.O., was handed his card by Solly Pernick, business agent for New York I. A. Local 1, who for many years has negotiated stagehand matters with the Major. It goes without saying that there was plenty of food and other temptations to the palate and a fine program of entertainment amid a pervasive atmosphere of hilarity and fellowship — all of which added up to one of the most successful gatherings in the history of the Club. Officers and members of the 25-30 Club extend a most cordial invitation to all I. A. men, when they are in the New York area, to attend their meetings. Projection Worthies Present Among those present, in addition to those already mentioned, were the following: Charley Mueller, chief of Radio City Music Hall; Nat Ripp, RCA; Ralph Kautzky, president of Associated Electronic Engineers, organization of I. A. sound servicemen; Herman Gelber, president of Local 306; Joe Engle, projectionist Local 640; Cy Braunstein, film editors Local 771; Joe Clayton, Local 306, maker of Clayton takeup devices; Herman Landwehr, managing director, Capitol Theatre, N. Y. City. Also Jimmy Frank, Allen Smith, and W. Nayfash, National Theatre Supply Co ; Harry Rubin, director of projection, Paramount Theatre; from International Projector Corp., Arthur Meyer, P. A. McGuire, R. W. Servies, and Rudy Kneuer; from Hudson County, N. J., I. A. Local 384 a delegation comprised of Tony Boscarelli, AI Kaye, Tom Neathery, Walter Bemis, Toby Abramowitz, and Henry Stuber. Also Abe Lang, Bob Goldblatt, Eddie Stewart, Harry Mackler, Charlie Eichhorn, Cecil Wood, Jr., Otto Kafka, Bob Levy, John Koler, Barney Weiner, Freddie Stofregen, Sr. and Jr., Paul Seigman, Abe Seligman, Joe Abrams, and Jim Finn. INTERNATIONAL PROJECTIONIST • January 1947 21