Finder \Find"er\, n.
1. One who, or that which, finds; specifically (Astron.), a
small telescope of low power and large field of view,
attached to a larger telescope, for the purpose of finding
an object more readily, called also a {finder telescope}
or {finder scope}.
[1913 Webster +PJC]
2. (Micros.) A slide ruled in squares, so as to assist in
locating particular points in the field of vision.
[Webster 1913 Suppl.]