SMPTE ST 231-2004 Motion-Picture Film (8-mm Type R) - Camera Aperture Image and Usage.pdf

1、 1 Scope 1.1 This standard specifies the dimensions of the camera aperture image and its relative position to the reference edge and the perforations of 8-mm type R motion-picture film. The location of the perforations is based on dimensions given in SMPTE 239. 1.2 This standard also specifies the p

2、osition of the emulsion, the frame rate, and the orientation of the area being exposed for 8-mm type R film as used in a motion-picture camera. 2 Dimensions 2.1 The dimensions shall be as given in figure 1 and table 1 and shall apply to measurements of the aperture image as formed on fresh film, pro

3、perly exposed and processed. 2.2 The angle between the vertical edges of the aperture image and the edges of normally positioned film shall be 0 . 2.3 The angle between the horizontal edges of the aperture image and the edges of normally positioned film shall be 90 . 3 Camera usage 3.1 Emulsion posi

4、tion Except for special processes, the emulsion shall be toward the camera lens as shown in figure 1. 3.2 Frame rate 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 applications. Fo

5、r 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 nonstandard rates may be used for special motion-picture systems. The use of nonstandard frame rates requires notification

6、 and agreement of all parties concerned with the use of the particular film. NOTES 1 Dimension B, vertical height of aperture, must be maintained in order to ensure a real (unexposed) frameline in the projector. Close control of the tolerances given for dimension B is necessary to enable dimensions

7、F and H to be held within satisfactory limits. These are the distances from the lower edge of the perforation and the horizontal edges of the framelines. Dimensions F and H represent the maximum conditions which can be tolerated due to misalignment of the horizontal centerline of the aperture openin

8、g and the optical centerline of the photographic lens. Dimensions B, F, G, and Page 1 of 3 pages SMPTE 231-2004 Revision of SMPTE 231-1999 Copyright 2004 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., White Plains, NY 10607 (914) 761-1100 Approved November 8, 2004 S

9、MPTE STANDARD for Motion-Picture Film (8-mm Type R) Camera Aperture Image and Usage SMPTE 231-2004 Page 2 of 3 pages H shall be measured to lines that are at right angles to the reference edge of the film and through a point where the radius (dimension R) is tangent to the horizontal framelines (see

10、 figure 1). 2 The centerlines of the aperture image are normally on the optical center of the camera. The optical axis of the camera is defined as the mechanical axis or centerline of the sleeve or other device for holding the camera lens. Except for manufacturing tolerances, it coincides with the o

11、ptical axis of the lens. 3 Dimension J shows the limits by which the frameline may be out of square with the reference edge of the film, but, at all times, this should be confined within the area designated by dimension G. FILM AS SEEN FROM INSIDE CAMERA LOOKING TOWARD CAMERA LENS; EMULSION AWAY FRO

12、M OBSERVER Figure 1 Camera aperture image Table 1 Specifications Dimensions 1)Inches Millimeters A 0.192 nom 4.88 nom B 0.145 + 0.003 0.002 3.68 + 0.08 0.05 D 0.113 max 2.87 max E 0.297 min 7.54 min F 0.018 min 0.46 min G 0.002 0.007 min max 0.05 0.18 min max H 0.032 max 0.81 max J R 0.010 max 0.25

13、max 1) See notes. SMPTE 231-2004 Page 3 of 3 pages Annex A (informative) Additional data A.1 If the 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 figure 1. The exact amount of this dif

14、ference will depend upon the f-number and focal length of the camera lenses used and upon the distance between the emulsion and the physical aperture. 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 i

15、mage such that the exposed area will always be larger than the area of the projector aperture. This standard meets this objective without causing double exposure of the area between frames. A.3 Dimension G, the distance between adjacent framelines, has been limited carefully so as to make it possibl

16、e to keep both framelines masked simultaneously by the projector aperture. In addition, dimensions F and H have been established to limit the distance that any part of the frameline can depart from the bottom edge of the perforations. This is to minimize the necessity for frequent adjustment of the framing device on the projector. Annex B (informative) Bibliography SMPTE 239-2004, Motion-Picture Film (16-mm) Perforated 8-mm Type R, 2R