Understanding And Using The Equatorial Mount - Orion Observer 90mm Instruction Manual

Figure 6. Slide the counterweight onto the counterweight shaft.
lock knob
Figure 7. Thread the counterweight shaft into the mount housing until
tight.
retighten the lock ring behind the objective lens cell. The finder
scope's focus should not need to be adjusted again.
IV. Understanding and Using
the Equatorial Mount
Balancing the Telescope
To insure smooth movement of the telescope on both axes of the
equatorial mount, it is imperative that the optical tube be properly
6
Groove
R. A. cable
.
Figure 9
The installed slow motion cables should appear as
shown, with the shorter one on the right ascension axis.
balanced. First we'll balance the telescope with respect to the
R.A. axis, then the Dec. axis.
1. Keeping one hand on the telescope optical tube, loosen
the R.A. lock knob (see Figure 16). Make sure the Dec.
lock knob is locked, for now. The telescope should now
be able to rotate freely about the R.A. axis. Rotate it until
the counterweight shaft is parallel to the ground (i.e.,
horizontal), as in Figure 17.
2. Now loosen the counterweight lock knob and slide the
weight along the shaft until it exactly counterbalances
the telescope. That's the point at which the shaft remains
horizontal even when you let go of the telescope with both
hands.
3. Retighten the counterweight lock knob. The telescope is
now balanced on the R.A. axis.
4. To balance the telescope on the Dec. axis, first tighten
the R.A. lock knob, with the counterweight shaft still in the
horizontal position.
5. With one hand on the telescope optical tube, loosen the
Dec. lock knob. The telescope should now be able to
Thumbscrew
.
Figure 8
Attach
the two slow motion
cables to the gear
shafts by orienting
the cable so that the
thumbscrew lines
up with the groove
of the gear shaft.
Then tighten the
thumbscrew.
Dec. cable