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野外地质技术照片除要求有最佳清晰度外,丰富的层次与和谐的影调则是不容忽略的问题。特别是在夏季,要避免产生高反差景物的不良后果,单纯地依赖调整曝光组合,效果不会显著。在摄影的过程中影响反差的因素是多种的。诸如:胶卷的感光度;滤色镜的运用;控制冲洗“格玛”值;底片的超比例减薄;暗房制作技术等等。一、胶卷的感光度:高速胶卷[GB24°以上)的卤化银颗粒较粗大,反差系数小,而曝光宽容度却较大。因此在夏季野外摄影选用它,配合D-76或D-23显影剂使用,有利于以较小的密度递增系数记录较大的明暗间距,同时曝光正确的安全性也相应增加。
In addition to the best definition of geology and technical photos in the field, rich layers and harmonious tone can not be ignored. Especially in the summer, to avoid the adverse consequences of high-contrast scenes, relying solely on adjusting exposure combinations, the effect will not be significant. There are many factors that influence the contrast in the process of photography. Such as: film sensitivity; the use of color filters; control flushing “Gema ” value; film than the thinning; darkroom production technology and so on. First, the sensitivity of film: high-speed film [GB24 ° above] silver halide particles larger, contrast coefficient is small, but exposure tolerance is larger. Therefore, the use of it in summer field photography, coupled with the use of D-76 or D-23 developer, is advantageous for recording larger dark / light spaces with smaller density increments, and the correct safety of exposure is also increased accordingly.