Orion 9966 - Manual (Page 9)

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level, but it should be placed on somewhat flat ground or pave-
ment 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
The Dobsonian base of the SkyQuest XT12 permits motion of
the telescope along two axes: altitude (up/down) and azimuth
(left/right) (see Figure 17). This is very convenient, since up/
down and left/right are the most “natural” ways that people
aim. As a result, pointing the telescope is exceptionally easy.
Simply take hold of the navigation knob and move it left or
right so the base rotates about its central azimuth bolt, and
move it up or down so the altitude side bearings rotate in the
base’s cradle. Both motions can be made simultaneously and
in a continuous manner for easy aiming. Move the telescope
gently — let it glide. In this way you can point the telescope to
any position in the night sky, from horizon to horizon.
Focusing the Telescope
With the 25mm eyepiece inserted in the focuser, 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 eye-
piece while slowly rotating the focusing knob in the opposite
direction. You should soon see the point at which focus is
reached.
The thumb screw on the top of the body of the focuser (Figure
16) will lock the focuser drawtube into place once the tele-
scope is properly focused. Before focusing, remember to first
loosen this thumb screw.
If you find the drawtube tension when focusing is either too
tight (focus knob is difficult to turn) or too loose (image shifts
when focusing), you can adjust it by tightening or loosening
the two drawtube tensioning set screws on the focuser. These
are the two small set screws located on either side of the
focus lock thumb screw. Adjusting these set screws requires
a 1.5mm hex key.
Viewing with Eyeglasses
If you wear eyeglasses, you may be able to keep them on
while you observe. This requires your eyepieces to have
enough eye relief to allow you to see the whole field of view.
You can see if your eyepieces have enough eye relief by look-
ing 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.
Now look in the finder scope. Is the object visible? Ideally it
will be somewhere in the field of view. If not, some coarse
adjustment to the finder scope bracket’s alignment thumb-
Figure 18. The view through a standard finder scope and a
reflector telescope is upside down. This is true for the SkyQuest and
its finder scope as well. Figure 17. The SkyQuest has two axes of motion: altitude (up/
down) and azimuth (left/right).
Altitude
Azimuth
Naked-eye view
View through finder scope and telescope