望远镜放大倍数 Magnification
（重定向自Angular Magnification）
光学望远镜的放大倍数是指被观测物体的张角，在经过望远镜的光学系统后被扩大多少倍。比如1000米外一个1米大小的物体，肉眼直接观测时，其张角约为0.001弧度；用放大倍数为10倍的望远镜观察该物体，其张角为0.01弧度，相当于肉眼从100米外观察该物体。
放大倍数的计算公式如下：![M={F/f}](/Images/godic/202412/21/dd61e7bf88de6c7983ad6dfedb63d7c01508.png")
其中M表示放大倍数，F表示物镜的焦距，f表示目镜的焦距。
望远镜的放大倍数通常刻在镜身上，用倍数×物镜口径来表达。比如8×30，表示该望远镜放大倍数为8倍，物镜口径为30毫米。
![The stamp appears larger with the use of a magnifying glass](/Images/godic/202412/21/Magnifying_glass21508.jpg")
![Stepwise magnification by 6% per frame into a 39 megapixel image. In the final frame, at about 170x, an image of a bystander is seen reflected in the man's cornea.](/Images/godic/202412/21/-Identifiable-Images-of-Bystanders-Extracted-from-Corneal-Reflections-pone.0083325.s001.ogv1508.jpg")
![A Thin lens where black dimensions are real, grey are virtual. The direction of the arrows can be used to describe cartesian +/- signage : from the centre of the lens, left or down = negative, right or up = positive.](/Images/godic/202412/21/Basic_optic_geometry1508.png")