Orion Sirius EQ-G Instruction Manual page 17

Figure 18.
Gently push the telescope horizontally to determine
direction of optical axis offset.
just enough to place Polaris HALF the distance back to the
center of the illuminated reticle eyepiece (Figure 20).
14.Repeat steps 7 to 12 until Polaris remains in the center
of the eyepiece field of view, or moves slightly around the
center, when the mount is rotated about the R.A. axis.
15. Retighten both the tube ring attachment screws.
Note: This calibration method can be applied to both refract-
ing and reflecting telescope designs. Differences in the optical
path of telescopes do not affect how the telescope tube and
tube rings should be adjusted on the mounting plate.
appendix B: Periodic Error
a.
Figure 17a‑b.
Rotate the telescope 180° about the R.A.axis.
b.
Figure 19a.
Adjust the optical axis offset screws this way if
Polaris moves toward the center of theeyepiece when the tube is
pushed as in Figure 18.
Figure 19b.
Adjust the
optical axis offset screws this
way if Polaris moves away from
the center of the eyepiece.
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