Orion EQ-G instruction manual Attaching a Telescope, Balancing a Telescope

3.Thread the center support shaft up through the tripod head and into the bottom of the equatorial mount until tight. Use the upper knob on the center support shaft to do this. The equatorial mount should now be firmly connected to the tripod.

4.Remove the knob and washer from the bottom of the center support shaft. Slide the tripod support tray up the bottom of the central support shaft until the three tray arms are touching the legs of the tripod. The flat side of the support tray should be facing up. Make sure the “V” of each tray arm is against a tripod leg. Place the washer on the center support shaft against the tray, and follow it by threading the knob all the way up the center support shaft until it is tight against the tray. The tripod support tray pro- vides additional stability for the tripod, and holds up to five 1.25" eyepieces and two 2" eyepieces.

5.Loosen the counterweight shaft lock lever and fully extend the counterweight shaft. Retighten the lock lever.

6.Remove the knurled “toe saver” retaining screw on the bottom of the counterweight shaft and slide both counter- weights onto the shaft. Make sure the counterweight lock knobs are adequately loosened to allow the counterweight shaft to pass through the hole. Position the counterweights about halfway up the shaft and tighten the lock knobs. Replace the toe saver at the end of the bar. The toe saver prevents the counterweights from falling on your foot if the lock knobs happen to come loose.

Your Atlas EQ-G mount is now fully assembled and should resemble Figure 1 except for the hand controller, which will be installed and explained in Section 7 (Dual-Axis) or Section 8 (GoTo) of this manual.

4. Attaching a Telescope

The Atlas EQ-G equatorial mount is designed to hold tele- scope tubes weighing up to approximately 40 lbs. For heavier telescopes, the mount may not provide sufficient stability for steady imaging. Any type of telescope can be mounted on the Atlas EQ-G, including refractors, Newtonian reflectors, and catadiotropics, provided a set of tube rings is available to cou- ple the tube to the mount. Orion sells a variety of telescope tube rings. Please visit our website at OrionTelescopes.com for details.

1.Attach the tube mounting rings to the tube ring mounting plate using the screws that come with the tube rings. The screws should go through the center holes in the ends of the mounting plate and rethread into the tube rings. Note that the side of the mounting plate with the central “groove” will be facing up (Figure 3). Use a small wrench to secure the tube rings to the mounting plate.

Note: The tube ring mounting plate included with the Atlas EQ‑G includes four optical axis offset adjustment screws; these are the socket head cap screws located at each cor- ner of the mounting plate. These adjustment screws will be explained further in Appendix A. For now, confirm that all four adjustment screws are sufficiently unthreaded so that the ends of their threaded shafts are flush with the top surface of the tube ring mounting plate.

Note: The optical axis offset adjustment screws should be oriented so that the threaded shaft extends upward through the top surface of the tube ring mounting plate. If the tube ring mounting plate arrives with the optical axis offset screws installed backwards, reverse their orientation before proceed- ing (Figure 3).

2.Loosen the black mounting plate lock knobs on the top of the equatorial mount. Place the mounting plate, with the tube rings attached, in the slot on top of the equatorial mount. Position the mounting plate so that it is centered in the slot. Re-tighten the mounting plate lock knobs until the plate is secure.

3.Open the tube rings and lay the telescope optical tube in the rings at about the midpoint of the tube’s length. Rotate the tube so that the focuser is at a convenient height for viewing. Close the tube rings and tighten them.

Note: The Atlas EQ-G mount is very heavy. Alone it weighs 54 lbs. With a large optical tube and counterweights it can easily weigh over 100 lbs. Keep this in mind when moving the tele- scope even small distances, and use assistance when need- ed. It is best to remove the optical tube and counterweights when moving the mount.

Note: Some telescope optical tubes (specifically Schmidt- Cassegrains and Maksutov-Cassegrains) have a mounting plate connected directly to the tube. For these telescopes, optional tube rings are not required. Simply follow step 2 (above) to connect the telescope to the mount.

Tube ring attachment screw

Flat washer

Lock washer

Optical axis offset adjustment screws

Figure 3. The tube ring mounting plate.

5. Balancing a Telescope

To ensure smooth movement of a 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, for now. The telescope should now be able to rotate freely about the right ascension axis. Rotate it until the counter- weight shaft is parallel to the ground (i.e., horizontal).

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