Motion Picture Herald (1954)

Vista Vision. U'he lens size corresponding to the proper aspect ratio at a projection throw of 120 feet are also indicated. Bear in mind that since projection lenses at present are made in only y^-inch steps, the actual picture sizes are more or less approximate, and in order to match picture masking height and width, it may be necessary to hie several aperture plate sets. ture 18 by 46 feet; then a screen 19 by 47 feet and its proper frame should be installed. On this screen it will be possible to project a 1.66 ratio picture equal to 18 by 30 feet, or a 1.85 ratio picture equal to 18 by 33 feet. When VistaVision is available, it will be possible to project a picture 18 by 36 using either a simple short focal length lens of and by moving side masking to selected positions for each type of picture. PROJECTION LIGHT SOURCES Now what projection lighting equipment must we have in order to make these new pictures bright enough for proper presentation? The new metallic screens give FIGURE 1 — Comparison of picture size and lens focal length for equal picture heights using all aspect ratios. Calculated for 120-foot throw. Aspect Ratio Picture Size Lens F. L. Picture Size Lens F. L. Picture Size Lens P. L. Picture Size Lens F. L. Picture Size Lens F. L. Picture Size Lens F. L. 1.33 24x32 3.00 22 X 29 3.25 20x26 3.75 18x24 4.00 16x21 4.75 I4x 19 5.25 1.66 24x40 2.50 22 X 36 2.75 20x33 3.00 18x30 3.25 I6x 27 3.75 14x23 4.25 1.75 24x42 — 22 X 38 — 20x 35 2.75 18 X 7? — 16x28 3.50 14x 25 4.00 1.85 24x44 2.25 22x40 2.50 20x 37 — !8x 34 3.00 I6x 30 3.25 14x 26 3.75 2.00 24x48 2.00 22x44 2.25 20x40 2.50 18 X 35 2.75 16x32 3.00 I4x 28 3.50 ANAMORPHIC: 2.00 24x48 3.00 22 x44 3.25 20x40 3.75 18x 36 4.00 16x32 4.75 I4x 28 5.25 2.35 24x 56 3.50 22 X 51 3.75 20x47 4.25 18 x42 4.75 16x 36 5.75 14x 33 6.00 2.55 24x61 3.50 22 X 56 3.75 20x 51 4.25 1 8 X 46 4.75 16x33 5.75 14x 36 6.00 I'his operation has been found tedious ; it must be undertaken with painstaking care, however, in order to get the various types of picture to ht their correct masking frames. Let us assume that the limiting factor for a theatre with a throw of 120 feet is the height and that this is 18 feet. In Figure 1 we note that the width of such a picture may range from 24 feet for the old aspect ratio of 1.33, up to width of 46 feet for the CinemaScope full ratio of 2.55. Let us assume that the front end of the auditorium can be rearranged to take a pic 2.75 inches; or if squeezed prints are available, using a 4-inch lens and a anamorphic attachment. With four-track stereophonic CinemaScope prints, and 4.75-inch lenses, a 46foot picture may be obtained. If a single track CinemaScope print is used, then for the same projection lenses a picture 18 by 42 feet can be projected. All of the above procedure can be performed ratber simply by using fixed top and bottom masking for the screen, since a height of 18 feet is maintained at all times; a considerable brightness gain when compared w'ith “wTIte” screens. This gain will vary from two to three times w-hen the screen is view^ed from the center, but it will drop to less than one when the screen is viewed from the extreme sides (angles of 45°). Since this reflectivity wdll drop as the surfaces age and become soiled, it has been found necessary to demand a light intensity at the center of the screen of about 10 to 12-foot candles. From Figure 2 we can determine with fair certainty wTat type of lamps, carbons and operating current combinations will produce this amount of light for a given picture wddth. l igure 2 has two columns Avhich are interesting. One shows maximum picture size when using short focal length lenses only. The other show's maximum picture size w'hen using the combination of lenses and anamorphic attachments. Let us consider our example In the light of these data: If we use regular lenses, an aspect ratio of 1.66, and a picture 30 feet wdde, it will be possible to utilize suprex carbon arcs w’ith 14-inch reflectors, burning a 9mm positive at a maximum current of 70 to 75 amperes. If, how'ever, we wanted to go to a ratio of 1.85, or 2.0, with pictures 34 and 36 feet wide, these lamps w'ould not provide sufficient light to produce the required brightness. Similarly, using anamorphic lenses to project VistaVision squeeze prints in a 2-to-l aspect ratio (1.5 compression) a pic FIGURE 2 — Picture widths allowing 10-12 foot-candles at center of screen, according to various types of carbon trims and lamp optical systems, for short focal length and anamorphic lenses. Pos. Carbon Arc Amps. Lamp Optics Short F. C. Anamorphic 8mm suprex 63-65 14" Reflector 28 Ft. 36-37 R. 9mm suprex 70-75 14" Reflector 32 Ft. 41-42 Ft. 1 0mm H. 1. 95-100 16" Reflector 36 Ft. 48-50 R. lOmm HItex 135 16" Reflector 42 Ft. 58-60 Ft. 1 1 mm H. 1. 122 16" Reflector 42 Ft. 58-60 Ft. 1 3.6mm H. 1. 160 Quartz Condensers 36 Ft. 48-50 R. 13.6mm Hitex 180 Quartz Condensers 42 Ft. 58-60 Ft. 26 MOTION PICTURE HERALD, SEPTEMBER 4, 1954