Orion 102mm EQ Getting Started, Spring-loaded tensioner, Balancing the Telescope

sure to loosen the R.A. and Dec. lock knobs before doing this. Retighten the R.A. and Dec. lock knobs once the equatorial mount is properly oriented.

7.Slide the counterweight onto the counterweight shaft. Make sure the counterweight lock knob is adequately loosened to allow the counterweight shaft to pass through the hole in the counterweight.

8.With the counterweight lock knob still loose, grip the coun- terweight with one hand and thread the shaft into the equatorial mount (at the base of the declination axis) with the other hand. When it is threaded as far in as it will go, position the counterweight about halfway up the shaft and tighten the counterweight lock knob. The retaining screw and washer on the bottom of the shaft prevent the coun- terweight from falling off (and onto your foot!) if the counterweight lock knob becomes loose.

9.Attach the 1/4"-20 adapter to the top of the equatorial mount using the bolts and washers that come with the adapter. Push the bolts, with washers attached, up through the holes in top of the mount and thread them into the bottom of the adapter. Tighten the bolts securely with the supplied wrench.

10.Connect the optical tube assembly to the 1/4"-20 adapter on the mount by threading the adapter’s shaft into the hole in the optical tube’s mounting block. Orient the optical tube so that is parallel to the length of the adapter, as it is in Figure 1. Tighten this connection firmly by rotating the knurled thumb wheel on the adapter counter-clockwise.

11.Attach the two slow-motion cables to the R.A. and Dec. worm gear shafts of the equatorial mount by positioning the thumb screw on the end of the cable over the indented slot on the worm gear shaft and then tightening the thumb screw. We recommend that the shorter cable be used on the R.A. worm gear shaft and the longer cable on the Dec. worm gear shaft. The Dec. worm gear shaft and cable should extend toward the rear of the optical tube, as is shown in Figure 1. If it does not, you will need to rotate the optical tube 180° on the 1/4"-20 adapter. Do this by first loosening the adapter’s knurled thumb wheel.

12.To place the finder scope in the finder scope bracket, first unthread the two black nylon screws 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 groove on the middle of the finder scope. Slide the eyepiece end (narrow end) of the finder scope into the end of the brack- et’s cylinder that does not have the alignment screws while pulling the chrome, spring-loaded tensioner on the bracket with your fingers (see Figure 3). Push the finder scope through the bracket until the O-ring seats just inside the front opening of the bracket’s cylinder. Now, release the tensioner and tighten the two black nylon screws a couple of turns each to secure the finder scope in place. The tips of the tensioner and nylon screws should seat into the wide groove on the rear of the finder scope’s body.

Spring-loaded tensioner

Eyepiece end of finder scope Alignment thumb screws O-ring

Figure 3. To install the finder scope in the finder scope bracket, pull the spring-loaded tensioner while inserting the eyepiece end of the finder scope into the bracket.

13.Insert the base of the finder scope bracket into the dove- tail holder on the optical tube. Lock the bracket into position by tightening the knurled thumb screw on the dovetail holder.

14.Remove the cap from the eyepiece adapter on the rear of the optical tube and insert the chrome barrel of the mirror star diagonal. Secure the diagonal with the thumb screws on the eyepiece adapter.

15.Insert the chrome barrel of the eyepiece into the star diag- onal. Secure the eyepiece with the thumb screws on the star diagonal.

The telescope system is now fully assembled. Keep the dust cover over the front end of the telescope when it is not in use. It is also a good idea to cover the eyepiece; use the cover cap that came with it.

4. Getting Started

Balancing the Telescope

To insure smooth movement of the telescope on both axes of motion (R.A. and Dec.) of the equatorial mount, it is impera- tive that the optical tube be properly balanced.

1.Keeping one hand on the telescope optical tube, loosen the R.A. lock knob. Make sure the Dec. lock knob is locked. The telescope should now be able to rotate freely about the R.A. axis. Rotate it until the counterweight shaft is par- allel to the ground (i.e., horizontal).

2.Loosen the counterweight lock knob and slide the counter- weight along the shaft until it exactly counterbalances the telescope (Figure 4a). That’s the point at which the shaft remains horizontal even when you let go of the telescope with both hands (Figure 4b).

3.Retighten the counterweight lock knob.

5