9
(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.
Setting the Altitude Tension Level
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.
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.
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.