Orion XT12 - Manual (Page 13)

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4. Using Your Telescope
One of the great benefits of the SkyQuest XT IntelliScope
Dobsonian is its ability to point to more than 14,000 celes-
tial objects, when used with the optional IntelliScope
Computerized Object Locator (controller). Use of the control-
ler is completely optional, and your telescope will function
perfectly well without it. However, the controller will greatly
enhance your observing experience by enabling you to quick-
ly and precisely locate even very faint objects. For more about
IntelliScope controller functionality, see Section 6.
Before using your SkyQuest telescope for the first time at
night, we recommend getting a feel for its basic functions dur-
ing daylight hours. Find a spot outdoors where you have a
clear view of some object or landmark that is at least 1/4-
mile away. It is not critical that the base be exactly level, but
it should be placed on somewhat flat ground or pavement to
ensure smooth movement of the telescope.
Remember, never point the telescope at or near the Sun with-
out using a proper solar filter over the front aperture!
Altitude and Azimuth Motion
The SkyQuest’s Dobsonian base permits smooth motion of
the telescope along two axes: altitude (up/down) and azimuth
(left/right) (Figure 28). For altitude motion, the altitude bear-
ings on the telescope tube glide on pairs of bearing cylinders
made from ultra-high molecular weight (UHMW) polyethylene.
For azimuth motion, the top baseplate moves on three Teflon
bearing pads attached to 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 17). Note that the altitude tension
knob is the knob just above the IntelliScope Controller Port.
The knob on the opposite side of the base is merely a retain-
ing 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. Loosen the altitude tension knob until
the front of the optical tube starts to drift upward. As it does
so, tighten the tension knob just enough to make the tube
stop drifting (Figure 29). 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.
Altitude
Azimuth
Figure 29. Adjust the tensioning knob until the altitude balance is
just right. The telescope should move easily in altitude without drifting
when you let go.
F i g u r e 2 8 .
T h e S k y Q u e s t
Intelliscope has two
axes of motion; alti-
tude (up/down) and
azimuth (left/right).