与定焦镜头相比，变焦镜头的放大倍率可变，无需调整光学系统的位置便可以不同分辨率对目标成像，能有效提高探测效率。
Compared with fixed focus lenses , zoom lenses have variable magnification without adjusting their position so that they can image with different resolution and enhance effectively their target detection efficiency .
变焦倍率