Orion 9874 instruction manual Balancing the Telescope, Inserting the Eyepiece

1.25" eyepiece	2" eyepiece adapter
adapter

	Focus lock
	thumbscrew
Focus	Collimation
knobs
	screw pair
	(3)

Figure 4. The 2" focuser of the Atlas 10 EQ.

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 alignment 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 Eyepiece

Loosen the thumbscrew on the 1.25" adapter (Figure 4) and remove the small dust cap. Insert the 25mm eyepiece into the focuser and secure it with the thumbscrew.

Your Atlas 10 EQ is now fully assembled and should resemble Figure 1.

Note about the Atlas 10 EQ Mount Weight

The Atlas 10 EQ mount is very heavy. Alone it weighs 54 lbs. With the optical tube and counterweights it weighs over 120 lbs. Keep this in mind when moving the telescope even small distances, and use assistance when needed. It is best to remove the optical tube and counterweights when moving the mount, or adjusting the length of the tripod legs.

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, for now. The telescope should now be able to rotate freely

a.b.

c.d.

Figure 5a-d.Proper operation of the equatorial mount requires that the telescope tube be balanced on the R.A. and Dec. axes. (a) With the R.A. lock lever released, slide the counterweights down the counterweight shaft until they just counterbalance the telescope tube. (b) When you let go with both hands, the tube should not drift up or down (c) with the Dec. lock lever released, loosen the tube ring lock clamps a few turns and slide the telescope forward or back in the tube rings. (d) When the tube is balanced about the Dec. axis, it will not move when you let go.

about the right ascension axis. Rotate it until the counter‑ weight 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 5a). That’s the point at which the shaft remains horizontal even when you let go with both hands (Figure 5b).

3.Retighten the counterweight lock knobs. The telescope is now balanced on the right ascension axis.

4.To balance the telescope on the declination axis, first tighten the R.A. lock lever, with the counterweight shaft still in the horizontal position.

5.With one hand on the telescope optical tube, loosen the Dec. lock lever. The telescope should now be able to rotate freely about the declination axis.

6.Loosen the knurled ring clamps on the tube rings a few turns, until you can slide the telescope tube forward and back inside the rings (this can be aided by using a slight twisting motion on the optical tube while you push or pull on it) (Figure 5c).

7.Position the telescope in the tube rings so it remains hori‑ zontal when you carefully let go with both hands. This is the balance point for the optical tube with respect to the Dec. axis (Figure 5d).

8.Retighten the knurled rings clamps.

The telescope is now balanced on both axes. When you loos‑ en the lock lever on one or both axes and manually point the telescope, it should move without resistance and should not drift from where you point it.

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