Pole finder
A polar finder is a sighting device that serves to align the equatorial mount of a telescope parallel to the earth's axis .
application
In the interior of the polar finder there is usually an etched glass plate with various symbols for more precise alignment of the telescope to azimuth and pole height .
With the help of the setting circles on the outside of the mount, which are located at the end of the eyepiece of the polar finder, you first align the symbols with the date and time so that they match the conditions in the sky. Now the symbols of the polar finder can be brought into line with the star or the stars behind it by setting the azimuth and polar elevation. The telescope is then adjusted with sufficient accuracy for direct observation. For long exposures in astrophotography , however, an even more precise adjustment is required; the so-called Einscheinern .
Northern hemisphere
North of the equator , the target is the Polar Star , which is located near the celestial pole . A small cross in the center, a ring around the outside and a small circle on this ring can be seen on the glass plate. If the North Star is in the small circle, the right ascension axis of the telescope points to the celestial north pole.
Southern hemisphere
There is no prominent star in the southern hemisphere, such as the North Star in the northern hemisphere. However, some polar finders also have a setting aid for the southern hemisphere; they are markings for the brightest stars in the octant constellation . If all the stars are within the auxiliary circles, the cross in the middle of the polar finder points to the south celestial pole.