viewfinder
/ˈvjuːfaɪndər/Definitions
1. noun
An optical instrument or electronic device used to frame and view the scene to be photographed or displayed, often consisting of a set of lenses or a display screen.
“The photographer adjusted the viewfinder on her camera to get the perfect shot.”
2. noun
A device used in telescopes to locate and view celestial objects.
“The astronomer used the viewfinder to find the constellation in the night sky.”