Orion 9968 Balancing the Telescope, Using Your Telescope, Installing the Finder Scope

Figure 4a-d.Proper operation of the equatorial mount requires that the telescope tube be balanced on both the right ascension and Declination axes. (a) With the R.A. lock lever released, slide the counterweights along the counterweight shaft until it just counterbalances the tube. (b) When you let go with both hands, the tube should not drift up or down. (c) With the Dec. lock knob released, loosen the mounting plate securing knob and safety thumbscrew a few turns and slide the telescope forward or backward. (d) When the tube is balanced about the Dec. axis, it will not move when you let go.

10.Place the right ascension rear axis cover on the equatorial mount.

Installing the Finder Scope

To place the finder scope (Figure 3a) in the finder scope brack‑ et, unthread the two black nylon thumbscrews until the screw ends are flush with the inside diameter of the bracket. Place the O-ring that comes on the base of the bracket over the body of the finder scope until it seats into the slot on the middle of the finder scope. Slide the eyepiece end (narrow end) of the finder scope into the end of the bracket’s cylinder opposite the adjustment screws while pulling the chrome, spring-loaded tensioner on the bracket with your fingers (Figure 3b). Push the finder scope through the bracket until the O-ring seats just inside the front opening of the bracket cylinder. Release the tensioner and tighten the two black nylon thumbscrews a couple of turns each to secure the finder scope in place. Insert the base of the finder scope bracket into the dovetail holder on the top of the focuser. Lock the bracket into position by tightening the knurled thumbscrew on the dovetail holder.

Inserting the Star Diagonal and Eyepiece

Remove the dust cap from the eyepiece adapter and insert the chrome barrel of the star diagonal into the eyepiece adapter and secure it with the thumbscrews. Remove the dust cap from the star diagonal and insert the 25mm Plössl eyepiece into the star diagonal and secure it in place with the thumbscrews on the diagonal. (Always loosen the thumbscrews before rotating or removing the diagonal or an eyepiece.)

Your telescope is now completely assembled and should appear as shown in Figure 1.

4. Balancing the Telescope

To ensure smooth movement of the telescope on both axes of the equatorial mount, it is imperative that the optical tube is properly balanced. We will first balance the telescope with respect to the right ascension (R.A.) axis, then the declination (Dec.) axis.

1.Keeping one hand on the telescope optical tube, loosen the R.A. lock lever. Make sure the Dec. lock lever is locked. The telescope should now be able to rotate freely about

the right ascension axis. Rotate it until the counterweight shaft is parallel to the ground (i.e., horizontal)

2.Now loosen the counterweight lock knobs and slide the weights along the shaft until they exactly counterbalance the telescope (Figure 4a). That’s the point at which the shaft remains horizontal even when you let go of the tele‑ scope with both hands (Figure 4b).

3.Retighten the counterweight lock lever.

4.Loosen the metal safety thumbscrew on the top of the equatorial mount. Then with one hand on the optical tube, loosen the mounting plate securing knob (Figure 4c).

5.Slide the optical tube into the dovetail slot until the mount‑ ing plate is positioned midway in the dovetail slot. Retighten the mounting plate securing knob.

6.Loosen the Dec. lock lever and test the balance of the opti‑ cal tube by letting go with both hands. If the optical tube does not move in either direction (Figure 4d) then the tube is balanced in declination. If the optical tube does move, then retighten the Dec. lock lever and repeat from step 4 above, this time sliding the optical tube to a new position and testing the balance again.

7.When the tube is balanced in declination, retighten the metal safety thumbscrew.

The telescope is now balanced in both axes. When you loos‑ en the lock lever on one or both axes of motion and manually point the telescope, it should not drift from where you point it.

5. Using Your Telescope

Focusing the Telescope

With the 25mm eyepiece inserted in the star diagonal, move the telescope so the front (open) end is pointing in the general direction of an object at least 1/4-mile away. Now, with your fingers, slowly rotate the focus knob until the object comes into sharp focus. Go a little bit beyond sharp focus until the image just starts to blur again, then reverse the rotation of the knob, just to make sure you’ve hit the exact focus point.

NOTE: The image in the telescope will appear reversed from left to right. This is normal for telescopes that utilize

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