The motion picture projectionist (Nov 1929-Oct 1930)

October, 1930 Motion Picture Projectionist 13 the next. Architects and exhibitors would undoubtedly raise violent protest. Two other possibilities exist, however, which should be considered. The first is to make the series of focal lengths differ by half of the 11 per cent, or 5.5 per cent. This leads to the series shown in Table I wherein each focal length is 5.5 per cent, shorter than the next longer. The constant difference of 5.5 per cent, is matched in the present series at the lens of 4.5 in focal length with a 0.25 in. interval between it and the next number. It would correspond to a change of picture size of about 1.1 ft. in a 20 ft. picture. It leads to a series containing nineteen numbers between 3.00 in. and 8.31 in., inclusive, and seems to the writer adequate. Table II Proposed Series of Focal Lengths, Interval 4 Per Cent. 3.00 in. 4.25 in. 6.00 in. 3.12 in. 4.41 in. 6.25 in. 3.23 in. 4.58 in. 6.50 in. 3.37 in. 4.75 in. 6.75 in. 3.50 in. 4.95 in. 7.00 in. 3.63 in. 5.15 in. 7.30 in. 3.78 in. 5.34 in. 7.58 in. 3.93 in. 5.56 in. 7.86 in. 4.08 in. 5.79 in. 8.20 in. The second possibility consists in dividing the 11 per cent, into three parts, making the constant difference one of about 4 per cent. This suggestion leads to the focal lengths set forth in Table II containing twentyseven focal lengths between 3.00 inches and 8.20 inches, inclusive. The minimum change in picture size computed on the basis of a 20-foot picture would here amount to about 0.8 feet. The difference between the two is that the manufacturer would have to make, and the dealer to stock, nineteen numbers to cover the range in the one case and twenty-seven in the second case. Since the success of the manufacturer and dealer both is to some extent at least essential to the success of the motion picture industry, it should not overlook the possibilities of economy offered by the first suggestion. For comparison it is to be noted that at the present time there are twenty-two numbers in the series from 3.00 to 8.25 inches. The first proposal involves only three fewer numbers. Discussion : Mr. Dubray: What are the permissible variations in focal length? Mr. Rayton: The Society adopted at one time a variation of 1 per cent from the indicated focus as the maximum permissible tolerance with the provision that if the lens is too long in focus it be marked plus, and if too short it be marked minus. Mr. Taylor: As one might wish to change from full aperture to re duced aperture, why is it not feasible to use a supplementary lens to increase the magnification in order to cover the original screen area? Mr. Rayton: That depends on the aperture of the illuminating system. If we are dealing with an illuminant making use of only a small part of the projection lens it will produce passable results. The demand is, however, for more and more light. This will, I think, lead to a demand for projection lenses of greater aperture. With an illuminant that fills the full aperture of such lenses the use of supplementary lenses will cause a noticeable loss in definition. Survey Shows Big Increase in Sound Pictures Recently an independent survey of the wired field situation was undertaken in the United States and Canada, which evidenced figures considerably at variance with those previously published. The sound equipment houses totaled 10,234 in the United States, while Canada averaged 362. Installations to be completed this year are approximated at about 4,266. It is expected that suitable for sound installation and this will clean up the field of theatres shows a grand total of 14,682. Wired Circuit Theatres The producer controlled sound houses are distributed over the different circuits in the following manner: Paramount-Publix 1,013 Fox 601 Warner Brothers 402 R. K. 0 119 Loew's 117 Total 2,252 Those circuits not producer controlled are estimated at 1,213, the total estimate of theatres in all chains being 3,465. The independent wired houses reaching a sum total of 6,769 leaves them in a superior position as compared with the 3,465 included in the chains. It naturally follows that the producers are just as dependent on the business of the "independent" theatre as the independent producer himself — and this condition will be further emphasized as the remaining 4,266 unwired houses come into line for sound. Volume Control Prime Reproduction Problem ONE of the greatest problems that exists today in the struggle to make reproduction as nearly perfect as possible is the tendency to keep the volume too loud, according to H. M. Wilcox, operating manager of Electrical Research Products. While Mr. Wilcox declined to make any estimate of the percentage of theatres in which sound quality is being impaired as a result, he stated that it was sufficiently large to constitute a definite obstacle toward the goal of adequate reproduction in every theatre in the country. "One of the contributing causes to this condition," Mr. Wilcox explained, "is the fact that many theatre managers try to regulate their sound volume by starting the fader at a louder intensity than will be necessary. From that they expect to lower it until they are satisfied with the volume. Work Up, Not Down "The fallacy of this procedure is that the ear, attuned to overvolume at the start, becomes volume-proof. Sensitivity is deadened, with the result that the listener is satisfied with the volume before it has actually been diminished to a level that should be used. "The proper way to regulate volume is to start the fader low and work it up to the proper volume. "Another trait that is retarding the realization of entirely satis factory reproduction is the tendency to adjust sound volume to meet the requirements of the worst seats in the house instead of the best. The individual judging volume quality often stands in the rear of the balcony or some other place where good reproduction is notoriously hard to obtain. The volume is adjusted where it is satisfactory to the bearer, there, instead of being adjusted so that it will be satisfactory for the vast majority of the seats. "The desirability for conservative volume should be obvious. The ground or surface noises, that are part of every talking picture as the phonograph needle's scraching is part of the talking machine is emphasized by volume. This is especially true where there are any silent stretches in the picture. Lower volume, on the other hand, tends to obliterate these noises. General Improvement "As we have stated before, reproduction quality and stability of operation are showing a steady improvement. In December, 1928, the service department of Electrical Research Products cleared 1,000 emergency calls among theatres that were then equipped. That represented a call per month per theatre. In July, 1930, the department cleared 480 emergency calls from 4,500 theatres, an average of about one call per theatre per year."