Transactions of the Society of Motion Picture Engineers (1922)

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ciliated. If thru the points of the R curve having these vakies of d. ordinates be drawn, deflections represented by these ordinates wih have the assumed values in lumens of the light falling upon the opal glass of the cell, divided by the intrinsic brilliancy of the source — or, since the lumens are proportional to the brilliancy — the lumens per unit brilliancy. Since the source brilliancy was the same for all the curves, the ordinates chosen in this way give also the lumens delivered to the projection lens per unit intrinsic brilliancy of the source. TABLE 1— MAXIMUM VALUE, C, OF ILLUMINATION FOR STANDARD APERTURE Focal Length Projection Lens 5.5" Projection Fig 2 Fig . 3 Fig . 4 Fig. 5 Curve Lens Source , N umber Diameter Side d, C di C d, C di C 1 2.5" .5" 14 . 0754 22 .0755 16 .0722 SO .0604 2 2.5" A" 14 .0651 22 .0656 18 .0650 80 .0493 3 2.5" .3" 14 .0507 22 .0496 19 .0470 78 .0334 4 2.. 5" .2" 14 .0280 22 .0270 15 .0260 80 .0175 5 2" .5" 14 .0498 22 .0513 16 .0481 80 .0441 6 2" .4" 14 .0460 22 . 0490 16 .0452 78 .0380 7 2" .3" 14 .0400 20 .0412 16 .0410 78 .0281 8 2" .2" 14 .0270 22 .0243 16 .0250 79 .0160 9 1.5" .5" 14 .0301 22 .0305 16 .0290 80 .0289 10 1.5" .4" 14 .0291 21 .0297 16 .0279 78 . 0270 11 1.5" ■?',', 14 .0276 21 .0286 16 .0278 80 .0210 12 1.5" 14 .0215 21 .0208 16 .0223 80 .0123 This method of evaluating the deflection avoids all question of the proportionality of deflection to light falling upon the cell. That these two quantities are closely proportional, however, is shown by the equi-spacing on the plates of the lines calculated for equal illumination differences. In Tables 1 and 2 are given the maximum values of the illumination (C) in lumens per unit brilliancy for the various combinations of source sizes, and projection lens diameters represented by the different curves of Figures 2 to 9. Summaries of 1 ables 1 and 2 will be found in Figures 10 and 1 1 respectively, llie relation between C and source side is here plotted for different diameters of projection lenses as indicated. TABLE 2— .MAXIMUM VALUE, C, OF ILLUMINATION FOR SAFETY STANDARD APERTURE. ' Focal Length Projection Lens 3.75" Curve Projection Fig. 6 Fi g. 7 f: ig. 8 Fig. 9 Lens Source — Number Diameter Side di C d. C d, C di C 1 2.0" . 5" .0739 25 .0651 18 .0675 84 .0483 2 2.0" .4" . 0669 26 . 0580 18 .0595 84 .0402 3 2.0" .3" .0515 26 .0441 17 .0404 SO .0286 4 2.0" .2" . 0300 25 .0249 18 .0240 84 .0160 5 1.75" . 5" .0564 25 .0543 18 .0535 82 .0.385 6 1 . 75" .4" .0547 26 .0516 18 . 0507 80 .0362 7 1.75" .3" .0450 26 ,0415 18 .0400 S2 .0265 8 1 . 75" .2" .0271 25 . 0240 19 .0235 79 .0151 9 1 . .5" . 5" .0425 23 .0421 18 .040() 80 .0346 10 1.5" .4" .0417 27 .0411 18 .0416 S3 .0310 11 1 . 5" .3" .0389 27 .0362 IS . 0360 SI .0232 12 1 . 5" .2" .0252 25 .0227 IS .0230 79 .0132 13 1.25" .5" .0298 23 .0390 IS .0297 SO .0253 14 1.25" .4" .()29fi 25 . 0298 IS .0290 SO .0239 15 1.25" . 3" . 0292 25 . 0288 IS .0294 SO .0198 16 1.25" .2" .0219 25 .0209 IS .0212 79 .0119 17 1.0" .5" .0194 25 . 0204 18 .0196 SO .0170 18 1.0" .4" .0194 2(i .0204 IS .0196 80 .0165 19 1.0" .3" .0185 26 . 0204 18 .0196 SO .0145 20 1.0" .2" .0160 25 .0180 18 .0171 80 .0103 25