1、STD-SMPTE 157-ENGL 1999 I 8357403 000350b 277 I SMPTE STANDARD SMPTE 157-1 999 Revision of ANSVSMPTE 157-1994 for Motion-Picture Film (8-mm Type S ) - Camera Aperture Image and Usage I 1 Scope , 1.1 This standard specifies the dimensions of the camera aperture image and its relative posi- tion to th
2、e reference edge and the perforations of 8-mm type S motion-picture film, as specified in ANSVSMPTE 149. 1.2 This standard also specifies the position of the emulsion and the frame rate for 8-mm type S motion-picture film. 2 Emulsion and film position 2.1 Except for special processes, the emulsion s
3、hall be toward the camera lens. 2.2 The perforation used for the film-positioning device shall be two perforations following the perforation adjacent to the image being formed when a positioning device is at the end of its stroke (the minus-2 position). This location coin- cides with that of the pos
4、itioning device required for the projected image and thereby improves steadiness through cancellation. 3 Dimensions 3.1 The dimensions shall be as given in figure 1 and table 1 and shall apply to measurements of Page 1 of 2 pages the aperture image as formed on freshly ex- posed and processed film.
5、3.2 The angle between the vertical and horizon- tal edges of the aperture image shall be 90“ f Mo to each other. 4 Frame rate 4.1 The standard frame rate for motion-picture photography is 24 frames per second. However, it is recognized that nonstandard frame rates are sometimes used for specific app
6、lications. For example, 24, 25, or 30 frames per second may be used for motion pictures intended for television; higher or lower frame rates may be used for special effects and analysis; and non- standard rates may be used for special motion- picture systems. The use of nonstandard frame rates requi
7、res notification and agreement of all parties concerned with the use of the particular film. 4.2 A frame rate of 18 frames per second shall be used for nonprofessional films using single- system audio or post-processed magnetically- striped film when the film is intended for projection at 18 frames
8、per second. I Copyright 0 1999 by THE SOCIETi OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hatisdale Ave., White Plains, NY 10607 Approved April 20,1999 (914) 761-1 100 STD-SMPTE L57-ENGL L999 M 8357403 0003507 LO3 LI SMPTE 157-1 999 PERFORATION USED TO POSITION FILM t-7 I TRAVEL ! EDGE FOR GUI
9、DING ANO DIMENSIONAL REFERENCE $OF INTENDED IMGE AREA FILM AS SEEN FROM INSIDE CAMERA LOOKING TOWARD LENS Table 1 - Specifications Dimensions Inches A 0.228 ref B 0.163 min C 0.170 nom 0.037 min 0.058 max D E 0.282 min H* 0.393 10.005 R 0.005 max Millimeters 5.79 ref 4.14 rnin 4.32 nom 0.94 rnin 1.4
10、7 max 7.16 min 9.98 I 0.13 0.13 max *Dimension H is the distance from the bottom edge of the picture frame to the bottom of the perforation which is two pitches following the perforation adjacent to that picture frame. - Figure 1 - Camera aperture image Annex A (informative) Additional data A.l If t
11、he aperture plate is not in the plane of the emulsion, the physical dimensions of the aperture in the camera will be slightly different from the dimensions given in the figure. The exact amount of this difference will depend upon the f/value and focal length of the camera lenses used and upon the di
12、stance between the emulsion and the physical aper- ture. This separation should be no greater than is necessary to prevent scratching of the film. A.2 It is the intent of this standard to provide a camera image such that the exposed area will always be larger than the area of the projector aperture.
13、 Observance of the dimen- sions given in the standard meets this objective without causing double exposure of the area between the frames. Annex B (informative) Bibliography A3 The centerline of the image area is given for conven- ience in interpreting the standard, facilitating such applica- tions
14、as the optical design of equipment, and assisting in the understanding of suitable mechanical embodiments related to the camera aperture image area. Note that the centerline of the image area is displaced from the centerline of the film by 0.013 in (0.33 mm) nominal. A.4 The pull-down claw is locate
15、d at the minus-2 perforation (see figure 1) with respect to the projector or camera aper- ture. The reason for selecting the minus-2 perforation for positioning is to obtain the positioning perforation as close as possible to the image being photographed, yet not so close as to interfere with the optical system and gate structure. SMPTE 149-1999, Motion-Picture Film (8-mm Type S) - Perforated 1 R Page 2 of 2 pages
