Orion 9966 - Manual (Page 11)

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expect the user to compensate for heavier accessories by
adding weight to the opposite end of the telescope tube. Such
counterweighting systems can be expensive and unwieldy.
The CorrecTension Friction Optimization system of the
SkyQuest XT12 Dobsonian, however, solves the finicky bal-
ance problem. The spring coils pull the tube down onto the
base, thereby increasing the friction on the altitude bearing
pads. With CorrecTension, the added weight of small front-end
loads will not adversely affect the balance of the telescope.
If you install an array of heavier accessories onto your
SkyQuest XT12’s optical tube, you may need at some point to
counterbalance the telescope with a counterweight system.
Transporting the Telescope
Even though it is a larger-aperture instrument, transporting
the SkyQuest XT12 is relatively easy. Remove any eye-
pieces from the telescope and eyepiece rack, and place
them in an eyepiece case. You can also remove the finder
scope and finder scope bracket, if you wish. Disengage the
CorrecTension springs by unhooking them from the posts on
the base, using the pull loops. The springs remain captive
on the telescope side bearings. The base and tube are now
disengaged and can be transported separately.
The tube is somewhat heavy, so don’t hesitate to have a
friend help lift the tube, if necessary. Do not use the naviga-
tion knob as a carry handle! It is not designed to support the
weight of the telescope tube and could break off or damage
the tube. To carry the base, simply grasp the handle on the
front of it.
When putting the SkyQuest XT12 into a vehicle, common
sense prevails. It is especially important that the optical tube
does not knock around; this can cause the optics to become
misaligned, and could dent the tube. We recommend trans-
porting and storing the tube assembly in a padded case for
proper protection.
4. Collimation
(Aligning The Mirrors)
Collimation is the process of adjusting the mirrors so they are
properly aligned with one another. Your telescope’s optics
were aligned at the factory, and should not need much adjust-
ment unless the telescope is handled roughly. Accurate mirror
alignment is important to ensure the peak performance of
your telescope, so it should be checked regularly. Collimation
is relatively easy to do and can be done in daylight.
To check collimation, remove the eyepiece and look down the
focuser drawtube. You should see the secondary mirror cen-
tered in the drawtube, as well as the reflection of the primary
mirror centered in the secondary mirror, and the reflection of
the secondary mirror (and your eye) centered in the reflection
of the primary mirror, as in Figure 19a. If anything is off-cen-
ter, as in Figure 19b, proceed with the following collimation
procedure.
The Collimation Cap and Mirror Center Mark
Your SkyQuest XT12 comes with a collimation cap. This is a
simple cap that fits on the focuser drawtube like a dust cap, but
Figure 19. Collimating the optics. (a) When the mirrors
are properly aligned, the view down the focuser drawtube
should look like this.
(b) With the collimation cap in place, if
the optics are out of alignment, the view might look something
like this.
(c) Here, the secondary mirror is centered under the
focuser, but it needs to be adjusted (tilted) so that the entire
primary mirror is visible.
(d) The secondary mirror is correctly
aligned, but the primary mirror still needs adjustment. When the primary mirror is
correctly aligned, the “dot” will be centered, as in
(e).