N a function of the f-number of a camera lens that takes into account the amount of light actually transmitted by the lens 摄影镜头光圈设置数 [photog]
t-number t值光圈
T-ara - Number Nine日文版
bit t drilling-capability number钻进能力数
N（名词） a function of the f-number of a camera lens that takes into account the amount of light actually transmitted by the lens 摄影镜头光圈设置数 [photog]