Extension tube

The principle and the implementation on the close-up photography has been studied.

研究照相机近摄原理及实现近摄的各种方法，针对课题“红外报警照相系统”的要求，运用延伸像距和缩短焦距的方法，对变像管荧光屏的近摄进行探讨和尝试，提出荧光屏进摄的规范。