1、SMPTE RP*37 64 W 8357403 0000335 534 W RP 17-1964 SMPTE RECOMMENDED PRACTICE Photographic Recording Technique for Measuring High-speed Camera Image Unsteadiness 1 Scope 1 .I Specificatlon This practice specifies a photographic method of recording and measuring high-speed motion-picture image unstead
2、iness. 1.2 Image-steadiness methods Existing image-steadiness methods are applicable to professional motion-picture cameras showing vertical image-steadiness accuracy within 0.0004 in (see annex A). 1.3 Application The procedure for measuring image unsteadiness, described in this practice, is far mo
3、re practical for high-speed, rotating-prism motion-picture cameras usually showing unsteadiness characteristics greater than 0.0004 in. 2 Measurements procedure 2.1 Film exposure 2.1.1 Double exposure Film shall be double exposed to produce overlapped images of the plus-sign target. 2.1.2 Target The
4、 target shall be opaque, except for a plus sign transmitting sufficient light for exposure through lines no wider than 1 -mm on an 8 in x 1 O in field. Page 1 of 3 pages 2.1.3 Backlighting The target shall be backlighted. 2.1.4 First exposure The first exposure shall be made in a professional camera
5、 known to afford image steadiness within 0.004 in. 2.1.5 Second exposure The second exposure shall be made in a high-speed mofion-picture camera, as shown in figure 1. Figure 1 -Typical set-up for second exposure 2.t.6 Exposure adjustments Exposure shall be adjusted for each camera to pro: duce equa
6、l density for both plus-sign images. 3 Recording unsteadiness data 3.1 Projection Processed film shall be projected onto a rotating drum wrapped with recording-type paper (cut 1.5 in x24 in), as shown in figure 2. 3.1.1 The projector shall be positioned approxi- mately 24 in from the drum, with both
7、 horizontal Copyright O 1992 by the SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., WhRe Plains, NY 10607 (914) 761-1100 Approved April 12,1964 RP 17-1964 Figure 2 - Projection of test film onto drum wrapped with recording paper lines focused on the recording paper and thro
8、ugh a 1/32-in vertical slit positioned directly in front of the recording drum. 3.1.2 The vertical slit shall transmit very small, dotlike sections of both horizontal lines representing the image characteristics of the reference camera and the high-speed camera. 3.1.3 The recorder shall rotate horiz
9、ontally one revolution per 100 ft of projection (or 6 in per minute), as shown in figure 3. Figure 3 - Driving mechanism of recording drum 3.2 Vertical unsteadiness The photographic record shall be processed conven- tionally and the camera evaluated for vertical un- steadiness. 3.3 Horizontal unstea
10、diness Horizontal unsteadiness shall be recorded in a similar manner by rotating the normally vertjcal lines 90“ optically with a mirror or dove prism, as shown in figure 4. Figure 4 - Position of dove prism for recording horizontal unsteadiness . 4 Characteristics of recording 4.1 Differential Diff
11、erential in amplitude between the traces indicates relative image unsteadiness of the high-speed camera, since projector unsteadiness is cancelled. 4.2 Comparisons The permanent recording should be compared with previous recordings to determine the degree of degradation. 5 Calculation of-image displ
12、acement Actual image displacement on the high-speed camera film shall be calculated by determining the magnifica- tion factor between the focal plane of the projector and the recording paper. When using a 2-in projection lens 2 ft from the recording drum, the magnification is approximately 1 OX. A t
13、ypical trace is shown in figure 5. Figure 5 -Typical trace shown on recording paper Page 2 of 3 pages RP 17-1964 Annex A (informative) Bibliography Robertson, A. C., A method of measuring the steadiness of motion picture cameras. Journal of the SMPTE, 68: 21-25; January 1959 Juiy 1944. Townsley, M. G., A method for measuring the steadiness of motion picture cameras. Journal of the SMPTE, 43: 45-50, Page 3 of 3 pages
