1、SMPTE RECOMMENDED PRACTICE Revision of RP 153-1994 Method for Measuring 35- and 70-mm Shutter Efficiency 1 Scope and purpose 1.1 This practice specifies the method and factors to be considered when measuring and reporting the comparative shutter efficiency (remaining useful light) of 35- and 70-mm p
2、rojectors. 1.2 The purpose of this practice is to provide guidelines for the evaluation of projector shutter performance, either in an operating movie theater or in a test laboratory. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute p
3、rovisions of this practice. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this practice are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. ANSVPIMA
4、 lT7.231-1998, Projection in Indoor Rooms - Part 1: Screen Illumination Test for Still Projectors 3 General method The general test method is to arrange test equipment for light measurements and take two readings in each point of the pattern described in 5.2, the first with the shutter in normal ope
5、ration and the second with the shutter stationary in the full open position. 4 Test instruments 4.1 The meters employed must be linear over the range of the readings to be taken, and not sensitive to shutter frequency. Page 1 of 2 pages 4.2 In a theater, the usual test equipment is a precision foot-
6、lamberi meter which is calibrated. 4.3 In a test laboratory, the usual test equip- ment is a precision foot-candle meter which is Cali b rat ed. 5 Test Set-up and pattern 5.1 The test instrument described above is to be mounted in a fixed manner; .e., the foot-lambert meter should be on a sturdy tri
7、pod, or the foot- candle meter mounted in a fixed mount or pole so that the test location of the reading is identical in the two cases specified in clause 3. 5.2 The test pattern should be the nine-point group as specified in ANSVPIMA lT7.231. This is recommended so that efficiency in different, but
8、 important, regions of the screen can be determined. 6 Calculations 6.1 Test readings are to be taken at each of the nine points, first with the shutter fixed open (see annex A.2), and then immediately with the shutter in normal running condition. 6.2 Divide the second reading for each point (shutte
9、r running) by the first reading for the same point (shutter fixed open). The result is a percentage of shutter efficiency for that point. The nine points must be considered separately, so that variations can be found. For simplicity, the nine readings can be averaged completely, or into three groups
10、the left three, the center three, and the right three-and reported as an average percentage of shutter efficiency. Copyright O 1999 by the SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartcdaie Ave., White Plains, NY 10607 (914)761-1100 Approved November 5,1999 RP 153-1999 Annex A (inf
11、ormative) Additional data Al With standard and generic projector shutters function- ing in the 50% range (two-bladed shutters), it is expected that all results will fall in the range of 40% to 60%. Results over 55% and below 45% should be considered suspect and be double-checked. A2 Note that operat
12、ion of a projector without film in the gate and with the shutter in a stationary open position may allow sufficient heat build-up in the lens system to endanger the lens. Therefore, it is recommended that this condition be allowed for only a few seconds at a time, and that measurements be made very quickly under such conditions. Page 2 of 2 pages
