See finder in Webster's New World College Dictionary
noun
a person or thing that finds
viewfinder
a small, low-powered telescope attached to a larger one, used to locate objects for closer view with the more powerful telescope
☆ a person who, for a fee (), initiates a business deal between others
See finder in American Heritage Dictionary 4
noun
One that finds: a finder of great hidden treasure.
A viewfinder.
A low-power, wide-angle telescope fixed to the body of a more powerful telescope and pointed in the same direction for initially locating an object to be observed.