Lensequation is derived by using Fermat's principle.
用费马原理推导了透镜的物像公式.
2
The camera is only part of the equation when it comes to image quality; the lens has an equally important role to play.
机身仅仅是决定成像质量的一部分，镜头同样重要。
3
To study the structure of telecentric beam path for zoom lens system, the axial displacement equation for the stop was deduced, which keep the system telecentric in all zoom position.