International projectionist (Jan-Dec 1952)

Accepted Standards for 16-mm Projection ii Freedom from Travel Ghost Z22.54-1946 1. Scope and Purpose 1.1 This standard describes a method of determining freedom from travel ghost in 16-mm sound motion picture projectors. 2. Definition 2.1 Travel ghost is a blurring effect seen on the screen and evidenced by vertical tails or light streaks added to the projected images of the transparent areas on the test film. It is caused by the projector shutter being out of synchronism with the intermittent mechanism, either by faulty adjustment or faulty design. 3. Test Film 3.1 The test film used for determining freedom from travel ghost shall carry a pattern of small transparent areas upon a dark back FIG. 1. Typical test pattern (X by approximately 8 diameters). This pattern, although still officially standard, is now used only for military testing and has been informally replaced, for industrial testing, by a "T" target. ground. There shall be at least six transparent areas, three of which shall be located not farther than 1/32 inch from the top of the frame and three not farther than 1/32 inch from the bottom of the frame. Four of the areas shall have their edges 1/32 inch from a side edge and either the top or bottom edge of the frame. The density of the transparent areas shall be less than 0.2 and the density of the dark background shall be greater than 2.2. 3.1.1 Standard Length of Film. The standard length of test film shall be 100 feet. 3.1.2 Leader and Trailer. Each test film shall have a suitable leader, title, and trailer. 4. Test Method 4.1 A test film in accordance with 2.1 shall be projected at standard sound speed of 24 frames per second (±2 percent) upon a white matte screen, the projected image of the projector picture aperture being of such size that a screen brightness of 10-foot lamberts is obtained with the projector shutter running, but with no film in the gate. The screen image of the test film shall be viewed from a distance equal to twice its width and presence or absence of travel ghost noted. 400-Cycle Signal Level Test Film (Z22.45-1946) 1. Scope and Purpose 1.1 This specification describes a 400-cycle signal level test film for use in testing 16-mm sound motion picture projection equipment. 2. Test Film 2.1 Recording. The test film shall have an originally recorded direct playback positive variable-area sound track recorded at an amplitude of 0.048 ± 0.0015 inch. The frequency of the recording shall be within ± 8 cycles of nominal frequency. The density of the dark portion of the sound track shall be between 1.7 and 2.0. The density throughout the length of the film shall be as uniform as is consistent with the state of the art. The combined base and fog density, measured as visual diffuse density, shall be 0*05 ± 0.01 when measured on an integrating sphere densitometer or a polarization densitometer. The wave form distortion of the recording shall not exceed 5 percent. 2.2 Film Stock. The film stock used for the test film shall be cut and perforated in accordance with the American Standard 16Mm Sound Motion Picture Film ; Cutting and Perforating for Negative and Positive Raw Stock, Z22.12-1941, or latest revision thereof. 2.2.1 Resistance to Shrinkage. The film stock used for the test film shall have a maximum lengthwise shrinkage of 0.50 percent when tested as follows: At least 20 strips of film approximately 31 inches in length shall be cut for measurement of shrinkage. After normal development and drying (not over + 80 F [+ 26.7 C]), the strips shall be placed at least Va inch apart in racks and kept for seven days in an oven maintained at + 120 F (-+ 49 C) and a relative humidity of 20 percent. The strips shall then be removed, reconditioned thoroughly to 50 percent relative humidity at + 70 F (-) 21.1 C), and the shrinkage measured by an adaptation of the pin-gage method outlined in Research Paper RP-1051 of the National Bureau of Standards. The percent shrinkage shall then be calculated on the basis of deviation from the nominal dimension for the length of 100 consecutive perforation intervals given in American Standard Z22.12-1941, or latest revision thereof. 2.3 Standard Length. The standard length of the 400-cycle signal level test film shall be 100 feet. 2.4 Measurement Requirements. Each film shall be measured for amplitude of the modulation, for image density, and for combined base and fog , density. The measurements shall be made at a point approximately midlength of the film and at points between 5 and 10 feet from each end. The results of the measurements shall be stated on a card furnished with each test film. 2.5 Leader and Trailer. Each test film shall be provided with a suitable leader, title, and trailer. Buzz-Track Test Film (Z22.57-1947) 1. Scope and Purpose 1.1 This specification describes a buzz-track test film used for checking the position of the sound scanning beam in 16-mm motion picture sound reproducers. 2. Test Film 2.1 The test film shall have originally recorded 300-cycle and 1000-cycle signal tracks on either side of the central exposed strip as shown in Fig. 1. The position of the tracks, weave in running film on the recorder included, shall be in accordance with Fig. 1. 2.2 The central exposed strip and the exposed portions of the two signal tracks shall have a density of 1.6 -f 0.4 2.3 Film Stock. The film stock used for the test film shall be cut and perforated in accordance with the American Standard Cutting and Perforating Dimensions for 16Millimeter Sound Motion Picture Negative and Positive Raw Stock, Z22.12-1947 (Revision of Z22.12-1941), or the latest edition thereof approved by the American Standards Association. 2.3.1. Resistance to Shrinkage. The film stock used for the test film shall have a maximum lengthwise shrinkage of 0.50 percent when tested as follows: At least 20 strips of film approximately 31 inches in length shall be cut for measurement of shrinkage. After normal development and drying [not over + 80 F (+ 26.7 C)], the strips shall be placed at least Va inch apart in racks and kept for 7 days in an oven maintained at + 120 F (+49 C) and a relative humidity of 20 percent. The strips shall then be removed, reconditioned thoroughly to 50 percent relative humidity at 70 F (21.1 C), and the shrinkage measured by an adaptation of the pin-gage method outlined in Research -UNIFORMLY OPAQUE STRIP N-« 300 CYCLES a IOOO CYCLES » □ O.02O -0.0000 IN. J K. 0.0l8i0°01 IN. a46±0.025 MM 0-51 lolooo MM „ „ +0.0000 ... 0.096 -0.0005 IN. 2.44 1°°°° MM FIGURE 1 Paper RP-1051 of the National Bureau of Standards. The percent shrinkage shall then be calculated on the basis of deviation from the nominal dimension for the length of 100 consecutive perforation intervals given in American Standard Z22.12-1947. 2.4 Each test film shall be provided with suitable leader and trailer, and a title or other markings to identify the film. 2.5 The standard length of test film shall be 100 feet. 24 INTERNATIONAL PROJECTIONIST • August 1952