1、 1 Scope This practice specifies a test procedure for classification of the depth of focus of a projection system. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this practice. At the time of publication, the edition i
2、ndicated 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. SMPTE 196M-2003, Motion-Picture Film Indoor Theater and Review Room Projectio
3、n Screen Luminance and Viewing Conditions 3 Test materials The test films used in this procedure shall contain resolution targets of at least 80, 68, 56, 48, 40, and 34 line pairs per millimeter. One test film shall contain these targets on black-and-white silver image film and the other shall conta
4、in these targets exposed in the magenta layer only of color positive release print film. NOTE The test film described in SMPTE RP 40 and available from the SMPTE as 35-IQ test film consists of 100 ft of black-and-white image and 100 ft of magenta image and is suitable for this test. 4 Test procedure
5、 4.1 Test film Assemble a test film of a minimum of 60 s (90 ft) or more, made from the test films described in clause 3. Half of the test film shall consist of the black-and-white film and half of the magenta image film. The test film shall be assembled from new or nearly new test materials. Any re
6、sidual deformation or other heat damage to the test films will render the test results invalid. (For a quick recheck, a 10-ft to 12-ft dual loop may be used.) 4.2 Screen luminance Before installing the test film, set the projector for use with 1.85:1 aspect ratio and adjust the screen luminance as u
7、sed for normal customer operation. The standard value for screen luminance is 16 fL with the testing details and tolerances described in SMPTE 196M. Page 1 of 2 pages RP 185-2004 Revision of RP 185-1995 Copyright 2004 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., W
8、hite Plains, NY 10607 (914) 761-1100 Approved November 8, 2004 SMPTE RECOMMENDED PRACTICE Classification of Projection Depth of Focus RP 185-2004 Page 2 of 2 pages 4.3 Resolution readings Install the test film and run the projector. Adjust focus critically on the black-and-white section of the film.
9、 Note the maximum resolution obtained in the center resolution targets of the black-and-white section of the film, and then, without readjusting focus, the maximum resolution obtained in the same targets on the magenta layer section of the film. 5 Evaluation of results Results shall be evaluated aga
10、inst the following classifications: Black-and-white section Magenta layer section line pairs/millimeter line pairs/millimeters Classification 80 68 or 80 Excellent 80 56 Very good 80 48 Good 80 40 Poor 80 34 Unacceptable Annex A (informative) Additional information A.1 Significance of test The silve
11、r particles forming the image on the black-and-white film will absorb significantly more of the infrared heat from the light beam than does the dye image forming the magenta layer image, causing greater heating of the black-and-white film and therefore greater curvature in the projection gate and co
12、nsequent shift in focus. Similarly, an image of greater density will absorb more heat than an image of lesser density. The two test images specified represent a wide difference in densities and, thus, relative heat absorption affecting focus. Thus, the difference in resolution between the two films
13、is an indication of the amount of heat in the light beam passing through the image and the densities of the two images, and the objective of this test is to determine whether the projection system has sufficient depth-of-field to retain adequate focus in both conditions. A.2 Changes to control focus
14、 shift The addition of infrared filtration between the light source and the film will reduce heat effects. A reduction in f/number of the projection lenses (e.g., f /2.0 to f /2.4) will increase the projection depth of focus. A.3 Other dual film testing Similar tests may be run using other film comb
15、inations such as triacetate- and polyester-based films of similar densities or of very high density compared to very low-density images. It should be ensured, however, that each test film in such a combination is capable of being individually focused to the same maximum resolution. Annex B (informative) Bibliography SMPTE RP 40-2003, Specifications for 35-mm Projector Alignment and Screen Image Quality Test Film
