Orion SKYQUEST XX12 - Manual (Page 16)

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2" adapter and secure it with the two thumb screws loos-
ened previously (Figure 29). The other eyepiece and 1.25"
adapter can be placed in the eyepiece rack until they are
needed.
4. To install the 1.25" Sirius Plössl eyepiece instead of the
2" Deep View eyepiece, keep the 1.25" adapter in the fo-
cuser, and make sure the two thumb screws on the 2"
adapter are tightened. Now, loosen the thumb screw on
the 1.25" adapter, do not loosen the two thumb screws
on the 2" adapter. Insert the 1.25" eyepiece into the 1.25"
eyepiece adapter, and secure it by retightening the thumb
screw on the 1.25" eyepiece adapter (Figure 30). The
other eyepiece can be placed in the eyepiece rack until it
is needed.
The basic assembly of your SkyQuest IntelliScope Dobsonian
is now complete. It should appear as shown in Figure 1. The
dust covers should always remain in place on the top of the
upper and lower tube sections when the telescope is not in
use. It is also a good idea to store eyepieces in an eyepiece
case and to replace the cover caps on the focuser and finder
scope when the telescope is idle.
3. aligning (collimating) the
optical system
To get the sharpest images, your telescope’s optical system
must be in precise alignment. The process of aligning the pri-
mary and secondary mirrors is called collimating. Collimating
is relatively easy to do and can be done in daylight or at
night.
Because the primary mirror is shipped separately from the
optical tube, the telescope’s optics must be collimated before
it can be used. Most of the adjustments will be to the tilt of the
primary mirror, as the secondary mirror has been pre-aligned
at the factory. It is also good idea to check the collimation
(optical alignment) of your telescope before each observing
session and make any necessary adjustments.
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 depicted in Figure 31a. If anything
is off-center, as in Figure 31b, proceed with the following col-
limation procedure.
the collimation cap and Mirror center Mark
Your XX12 comes with a collimation cap. This is a simple cap
that fits on the focuser drawtube like a dust cap, but has a
hole in the center and a reflective inner surface. The cap helps
center your eye so that collimating is easier to do. Figures 31b
through 31e assume you have the collimation cap in place.
As an additional aid in collimating, the primary mirror of the
XX12 has a tiny adhesive ring marking its exact center. This
center ring will not affect the images you see when observ-
ing with the telescope in any way (since it lies directly in the
shadow of the secondary mirror), but it will greatly facilitate
collimating when using the supplied collimation cap or other,
Figure 31. 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).
a.
b. c.
d. e.
drawtube
Reflection
of primary
mirror clip