A finder scope is a small telescope that rides piggyback on the main telescope. Its purpose is simple: to aid in aiming the main telescope toward objects of interest. By virtue of low magnification and a wide field of view, the finder allows you to see more of the sky than you can through the main telescope. The idea is that you locate an object in the finder scope and center it on the crosshairs, then look in the main telescope and — voila! — it will be waiting right there for you in the eyepiece, whether the object is a crater on the Moon or a faint galaxy tens of millions of light years distant.
