Telocentric lenses work with a wide depth of field. With a telocentric lens, you can image objects of different distances from the lens and the objects stay in focus.

具丝粒的镜(注:我猜是类似于针孔镜吧)具有阔之景深，以具丝粒的镜，你能够将由镜距离之目标物成像和保持目标物在焦。