American cinematographer (May 1930)

Twenty-two American Cinematographer May, 1930 B. ^ H. Continuous Printer (Continued from Page 19) Note carefully how the masks of the sound attachment inter- lock with the lower aperture jaw to prevent light leakage. In the early models of the B. K H. Printer, the printing light was controlled through the mobility of the jaws of the printing aperture. By enlarging or reducing the printing aperture more or less exposure was given the positive film for a uniform running speed of the machine. A refinement developed a few years ago added a new method of light control called the “back shutter,” which, as its name implies, consists of a variable aperture shutter located at ap- proximately mid-distance between the printing light and the aperture. The versatility of this method of light control is so great that it permitted to dispense with the varying in width of the printing aperture itself while retaining a great range of light intensities easily controlled from the outside of the ap- paratus. The “back shutter” proved invaluable in the development of the triple adjustment sound attachment, because it permitted to stabilize the printing aperture to a standard 5-16" dimension which is also the height dimension of the triple mattes. The “back shutter” method of light control is applied to the independent printing of both the picture or the sound record, as the occasion arises. Now let us turn for a moment to a consideration of the actual manner in which the three masks are arranged so as to control the final result in the print. At Fig. 3 is shown the complete unit so that its action can be more clearly visualized. Three masks are employed, the width of the center one being —.750" and of the two side masks—.170" each. They are made so that they fill the 5-16" high opening. These masks are made to very close limits, as may be expected, to insure ac- curacy in their action, and eliminate the possibility of light leaks at their adjacent sides. Each mask operates in accurately milled control slots in the main casting. On the under side, each mask has two slots cut, into which the pawls P (Fig. 3) engage. These pawls are held in place by the triple-tongued Spring S (Fig. 3). The slots in the masks are Vi " apart, so that the stroke of the masks is Yi ". This withdraws the masks sufficiently far back to avoid any interference with the printing light. Figure 2 demonstrates this more clearly than any further ex- planation. The middle mask is cut away just back of the part that blocks the aperture. This recessed portion comes within 1-16" of the front and is arranged so as to avoid any possibility of fringing due to reflections from the sides of the masks. In prac- tice. it insures the line between the picture and sound areas having sharply defined edges. The two side mattes arc milled with a slight rib on the sides adjacent to the middle mask. This rib is %" from the front of the mask and protrudes .014" from its side. When the middle mask (B Fig. 3) is pulled back, it en- gages this rib on the side mask and moves it over sideways. The mask is moved .017" at the aperture itself. This means that sound track does not cover as much space adjacent the picture area as it did before. Therefore, that portion of the film now uncovered (.017" wide) receives a double exposure, which re- sults in a black line, or light shield between the picture area and the sound track. Reference to the dimensional drawing (Fig. 9) and to Figures 4, 5, 6, 7, and 8 will show exactly what goes on. When the middle mask B (Fig. 4) is drawn back it engages the mask A (Fig. 5) and pushes it to the left. In this position the mask A (Fig. 5) covers the sound track proper and the portion of the negative marked Y (Fig. 9) is printed. However, when the sound track is to be printed the mask A (Fig. 6) is set back and the area marked X (Fig. 9) is printed. This over- lapping of the two exposures produces the black line between the sound and the picture area. As stated previously, the over- lapping is adjusted so that this line has a width of .017". To insure clarity in presenting this explanation of the modus operand! of the masks, it was assumed that the film was re- wound between the printing of the sound and picture areas. Now let us assume that we have printed our picture area as before with the masks set as in Fig. 5. (The negative will be in the forward running position) . Then if we desire to print the sound area without rewinding, we remove both the positive and negative films from the take-up spindles and put them on the feed spindles. The printer is again threaded up and the masks set in the position shown in Fig. 8 instead of position 6. Reference to the captions given in the figure will show how the masks are set for different conditions—it is obvious that the versatility of this sound attachment is all that can be de- sired. It can also be accepted that its accuracy is likewise. Movie Congress at Algeria TOURING the festivities to be organized in spring, to com- memorate the hundredth anniversary of Algeria as a French colony, an international educational film congress was held there last month. The congress comprised an exhibition of the most current types of film projection apparatus, cameras, etc.; lec- tures and films on public health and hygiene. The admission for exhibitors and the public, both to the exhibition hall and to the lectures, was free. The aim of the congress was to propa- gate the idea of motion pictures as a means of tuition. English Tax T T IS reported that theatres in Great Britain and Ireland con- tributed roughly 6,000,000 pounds last year to the Treasury in entertainments tax. The sum paid to the Treasury on this account from picture houses for the four months of last year, April to July inclusive, was 1,926,682 pounds, which was equivalent, roughly to 6,000,000 pounds a year. The fact that the picture public paid this vast sum was one more proof of the immense hold the cinema had on the British public, it was claimed. 30 Minutes of Newsreel Under Experiment by Fox Success of 30-minute newsreel shows three times daily at Fox houses in Chicago, Milwaukee and New Haven is expected to influence introduction of these programs into additional thea- tres of the circuit shortly. Newsreel programs arc dovetailed at the noon, supper and midnight shows with three different news- reels being used. Argentine Would Restrict U. S. Talking Pictures Buenos Aires—Charging that U. S. talking pictures are play- ing havoc with the spiritual and cultural standards of the coun- try, in addition to throwing native musicians out of work, “La Prensa” has started an earnest campaign to restrict English talkers.