Setting the Altitude Tension Level

(left/right) (Figure 14). For altitude motion, the altitude bear- ings on the telescope tube glide on pairs of bearing cylinders made from ultra-high molecular weight (UHMW) polyethyl- ene. For azimuth motion, the top baseplate moves on three Teflon bearing pads embedded in the ground baseplate.

To move the telescope, simply take hold of the navigation knob and gently move the tube up or down and left or right as desired. Both motions can be made simultaneously and in a continuous manner for easy aiming. When the telescope is pointed high in altitude, rotating the tube in azimuth can cause the base to “tip” because of the reduced leverage. In this case it is helpful to place your other hand on the base or the optical tube to help “guide” the tube.

The telescope should move smoothly with just gentle hand pressure. While azimuth friction is not adjustable, the altitude friction can be adjusted to the desired level by turning the alti- tude tension knob (Figure 10). Note that altitude tension knob is the knob just above the IntelliScope Controller Port. The knob on the opposite side of the base is merely a retaining knob; it does not affect altitude tension.

Adjustable tension is a feature of the SkyQuest’s exclusive springless CorrecTension Friction Optimization system. CorrecTension adds just the right amount of friction to keep the telescope tube in proper balance, even when other acces- sories are added on, such as a barlow lens or a heavier eyepiece.

A good way to set the altitude tension is to point the telescope at about a 45° angle with the eyepiece and finder scope removed. Loosen the altitude tension knob until the front of the optical tube starts to drift upward. As it does so, tighten the ten- sion knob just enough to make the tube stop drifting (Figure 15). When the eyepiece and finder scope are replaced, the motion should be ideal -- not too stiff, not too loose.

Figure 15. Adjust the tensioning knob until the altitude balance is just right. The telescope should move easily in altitude without drifting when you let go.

You will want to be able to “track” the motion of celestial objects while viewing them by making small movements of the telescope without experiencing jerking (too much tension) or overshooting of the desired position (too little tension).

Focusing the Telescope

With the 25mm Sirius Plössl eyepiece in the focuser and secured with the thumbscrew(s), 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 one of the focusing knobs 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.

If you have trouble focusing, rotate the focusing knob so the drawtube is in as far as it will go. Now look through the eyepiece while slowly rotating the focusing knob in the opposite direc- tion. You should soon see the point at which focus is reached.

Note About the Focuser Drawtube Lock Knob

The focusers of the XT8 and XT10 feature a drawtube lock knob. There are times when you may want to lock the draw- tube to preserve the focus setting (such as when using certain afocal photographic attachments). This is done by turning the focus lock knob (Figure 13) clockwise until it is tight. The focus setting will now be locked. When you need to adjust the focus again, be sure to loosen the lock knob.

The XT6 does not have a focus lock; instead it has a drawtube tension thumbscrew. It can be used to increase or decrease the amount of tension on the drawtube. If you feel the drawtube is moving too loosely when you turn the focusing knob, or if focus- ing feels too tight, make adjustments by turning the thumbscrew. Do not loosen it too much as there must be some tension to keep the drawtube secure in the focuser.

Viewing with Eyeglasses

If you wear eyeglasses, you may be able to keep them on while you observe, if your eyepieces have enough eye relief to allow you to see the whole field of view. You can try this by looking through the eyepiece first with your glasses on and then with them off, and see if the glasses restrict the view to only a portion of the full field. If they do, you can easily observe with your glasses off by just refocusing the telescope the needed amount. If you suffer from severe astigmatism, however, you may find images noticeably sharper with your glasses on.

Aligning the Finder Scope

The finder scope must be aligned accurately with the tele- scope for proper use. To align it, first aim the main telescope in the general direction of an object at least 1/4-mile away - the top of a telephone pole, a chimney, etc. Position that object in the center of the telescope’s eyepiece.

The finder scope uses a spring-loaded bracket that makes alignment of the finderscope very easy. As you turn either of the thumbscrews, the spring in the bracket’s tensioner moves in and out to keep the finder scope secure in the bracket.