In order to more easily locate objects in a telescope, astronomers use reflex finders and/or optical finder scopes. These devices show a wide area of sky and have either a red dot or a crosshair in the center indicating exactly where the main telescope is pointed. Since the main telescope is magnifying the image it is only showing a very small portion of the sky. Trying to get the main telescope to point precisely at a specific object in the sky can be difficult. Centering the desired object first in a finder or finder scope allows the user to point the main telescope precisely at the object. It saves time and is less frustrating than sweeping the telescope back and forth until the object pops into the eyepiece.
Reflex finders use a clear or lightly tinted window. In the center of this window is projected a small illuminated dot dot indicating where the telescope is pointed. The simple red dot finder (F001) is made of plastic, it is economical and is easiest to use. It has a simple red dot showing where the telescope is pointed. The multi-reticle finder (F002) has a red dot but one may turn a lever on the unit to change the dot to a small circle or cross.
Optical finderscopes are like a very small telescope. They magnify only a small amount and show several degrees of sky making it relatively easy to locate the desired object. Optical finderscopes also use an objective lens which gathers more light than the naked eye does. So you see more when looking through an optical finderscope than you do with the naked eye or a reflex finder. If you are looking for a barely visible star cluster, the optical finder reveals these dimmer objects. Correct image optical finders allow for natural movement; push the telescope left and the view moves to the left and vice versa. The larger the optical finder the more light it gathers so one can see even dimmer objects. The Stellarvue F50 optical finderscope is the highest rated on the market with a much sharper lens and higher contrast than less expensive units. All optical finderscopes have an eyepiece with a crosshair reticle. The crosshair indicates exactly where the main telescope is pointed. It is often difficult to make out the crosshair at night against the dark sky so we offer optional illuminators. These screw into the eyepiece and make the crosshair glow a red color making it clearly visible at night.