Pole finders are useful for correctly-aligning equatorial mounts. With this type of mount, the so-called hour axis should be parallel to the Earth’s axis. This is easy with a pole finder.
A set-up which is as precise as possible is mostly required for long exposure photography. For visual observation, just changing the degree of latitude settings and roughly setting up the mount using a compass is sufficient.
The pole finder allows polar alignment with an accuracy of 3 arc minutes. Polar alignment is very easy: simply align the North Star and two other stars in the field of view of the pole finder and rotate the mount until the stars are superimposed on the scales in the pole finder. This means you no longer need to make any length corrections or set the time and date. The PF-L II pole finder has red, dimmable lighting that switches off automatically after a few minutes to save the batteries.
Setting in
- Northern sky: Polaris, Delta UMI, 51 Cep
- Southern sky: Chi Octantis, Tau Octantis, Sigma Octantis