Orion SKYQUEST #27189 XT12I - Manual (Page 15)

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When putting the IntelliScope into a vehicle, common sense
prevails. It is especially important that the optical tube does
not get knocked around; this can cause the optics to become
misaligned, and could dent the tube. We recommend trans-
porting and storing the tube assembly in an optional padded
case for proper protection.
4. alignment (collimation)
of the optical system
To get the sharpest images, your telescope’s optical system
must be in precise alignment. The process of aligning the
primary and secondary mirrors with each other and with the
mechanical axis of the telescope is called collimation.
Your telescope’s optical system was collimated at the factory
and will probably not need any further adjustment. But rough
handling during shipment can knock the optics out of align-
ment, in which case you will need to recollimate the system.
Collimation is relatively easy to do and can be done in day-
light. It is a good idea to check the collimation of your tele-
scope before each observing session and make any neces-
sary 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 18a. If anything
is off-center, as in Figure 18b, proceed with the following col-
limation procedure.
the collimation cap and Mirror center Mark
Your SkyQuest XTi IntelliScope comes with a quick collima-
tion cap
(Figure 18). This is a simple cap that fits on the fo-
cuser 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 collimation is easier to perform.
Figures 19b through
19e assume you have the collimation cap in place.
As an additional aid in collimation, the primary mirror of every
SkyQuest XTi IntelliScope has a tiny adhesive ring marking
its exact center. This center ring will not affect the images you
see when observing with the telescope in any way (since it
lies directly in the shadow of the secondary mirror), but will
greatly facilitate accurate collimation when using the supplied
collimation cap or other, more sophisticated collimation devic-
es such as the Orion LaserMate Deluxe laser collimator. The
center ring should never be removed from the primary mirror!
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).
drawtube
Reflection
of primary
mirror clip
Primary mirror
center mark
Reflective surface
of collimation
cap
a.
b. c.
d. e.
Center
ring on
primary mirror