Outing . -ployed, and the sensitiveness of the plateor film. The lens works more or lessquickly as the diaphragm employed islarger or smaller, and here we have stillanother means of modifying our results. A large opening admits a greater amountof light through the lens, and so permits ofa shorter exposure than a smaller aperturewhich admits less light; but the smallerdiaphragm, by cutting off those rays oflight which enter the lens at the side (wherethey are not refracted equally with themiddle rays, and so do not give so exacta focus, producing a slight indistinction),secures a sharper pictur
Outing . -ployed, and the sensitiveness of the plateor film. The lens works more or lessquickly as the diaphragm employed islarger or smaller, and here we have stillanother means of modifying our results. A large opening admits a greater amountof light through the lens, and so permits ofa shorter exposure than a smaller aperturewhich admits less light; but the smallerdiaphragm, by cutting off those rays oflight which enter the lens at the side (wherethey are not refracted equally with themiddle rays, and so do not give so exacta focus, producing a slight indistinction),secures a sharper picture, as photog-raphers say, with finer definition and de-tail. One quickly grows accustomed tothe use of the diaphragms, however, andgenerally employs a medium-sized one inthe lens ; the operator must also be fa-miliar with the relative sensitiveness ofthe plate or film which he uses, but this isnot difficult. It requires a skilled judg-ment, however, to decide as to the qual- INSTANTANEOUS PHOTOGRAPHY. 293. CHEWING THE CUD. ity of light and the speed of the movingobject. Color has much to do in modifying re-sults ; a light or highly actinic color,such as blue, violet or indigo, requires amuch shorter exposure than even a betterilluminated object of a dark or non-ac-tinic color, such as red, orange or amateurs employ orthochromatic orcolor-sensitive plates, which enable themto equalize somewhat the differences ofcolor shades in their subjects, and to moreaccurately photograph the different colorvalues of nature. Assuming that an instantaneous plateor film has been correctly exposed on asubject which was well lighted and in agood position, the interesting but diffi-cult process of development remains tobe successfully accomplished before theresult is assured. And in developing thelatent image on the photographic plate,perhaps more skill and judgment are re-quired to insure a successful result thanin any previous stage of the work. Thereare innumerable formulas for deve
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