Polar finder adjustment

Pole finder adjustment

If the polar star can be aimed at with the pole finder, it is possible to align the right ascension axis of the telescope parallel to the Earth's rotation axis via the azimuth and pole height adjustment. However, this requires the optical axis of the pole finder in the mount block to be aligned parallel to the right ascension axis.
The more accurate the pole finder adjustment is, the more precise the alignment can be and the better the tracking and long time exposures will be.
This adjustment has to be done only once after the purchase of the telescope or pole finder. If the adjustment screws are not operated afterwards, the adjustment is retained.

When rotating the declination axis, there are areas where the view through the pole finder is obstructed due to the design of the mount. For the adjustment, the declination axis is therefore rotated so that a free view is possible. Turned 90° to the left or right, the view is obstructed, and at 180° it is free again. Now the adjustment can be started.


The following is a step by step guide to adjust a pole finder in the mount.

  • Through the pole finder, a prominent object is focused centrally at a distance of several hundred meters. (The image is upside down due to the optical nature of the pole finder).
  • Since Polaris is not exactly on the rotation axis of the earth, a circle is indicated in the pole finder as the movement line of Polaris around the north celestial pole.

View through the pole finder
  • The right ascension axis must now be rotated by 180°.
  • If the cross remains centered on the object, no further adjustment is required. If an image like the one in the adjacent figure appears, the following steps must be performed.

Offset with misaligned pole finder
  • Using the small set screws that hold the pole finder in the mount, the pole finder center is now moved back half the distance to the object.

Displacement of the misaligned pole finder
Now the right ascension axis is rotated 180° back to its original position. → As a result, the polar finder center will now be exactly on the other side of the object.
Turning back the pole finder
  • The center of the pole finder is now centered on the object via the azimuth screws and the pole height adjustment (no longer use the set screws of the pole finder).
  • If the center remains on the object when the right ascension axis is rotated, everything is correctly adjusted. Otherwise, steps (3) - (5) must be repeated.

View through corrected pole finder