Finder
Also called: finderscope, red-dot finder, Telrad, RACI.
A small sighting device on the telescope for aiming: a red-dot or Telrad reflex sight, or a small magnifying finderscope.
Reflex finders project a red dot or rings onto the sky with no magnification — perfect for pointing at naked-eye stars. A magnifying finderscope (6×30, 8×50) shows fainter stars for star hopping; right-angle versions are comfortable on a Dobsonian. Most observers use one of each.