有效曝光时间偏差 Ａｂｌｅｎｋｕｎｇ ｄｅｒ Ｂｅｌｉｃｈｔｕｎｇｚｅｉｔ ｄｅｖｉａｔｉｏｎ ｏｆ ｅｘｐｏｓｕｒｅ ｔｉｍｅ 指实际有效曝光时间与名义有效曝光时间的差值。常用符号ｂ表示。它由下式确定：式中：ｔ■为有效曝光时间名义值； ｔ■为中心有效曝光时间实测 Ablenkung der Belichtungzeit deviation of exposure time refers to the difference between the actual effective exposure time and the nominal effective exposure time. Common symbol b said. It is determined by the following formula: where: t ■ is the nominal value of the effective exposure time; t ■ is the effective exposure time measured at the center