optical device that helps a user to find the target of interest
同义词：finder, view finder
viewfinder详细解释
view.find.er n.（名词）A device on a camera that indicates, either optically or electronically, what will appear in the field of view of the lens.取景器：照相机上的光学或者电子设备，用以显示出现在镜头里的东西
