5
Installing the Eyepiece Rack
The aluminum eyepiece rack is a standard accessory on
SkyQuest XT10 Dobsonians. It holds three 1.25" eyepieces and
one 2" eyepiece in a convenient place on the base, within easy
reach while you’re observing. A 1.25" barlow lens also can be
held in the rack. About halfway down the left side panel of the
base you will notice two predrilled starter holes, about 6" apart.
Take the black wood screws and thread them into the starter
holes with a Phillips screwdriver. Then you can “keyhole” the
eyepiece rack onto the wood screws and continue tightening
the screws (Figure 4). If you want to be able to remove the rack,
do not tighten the screws too tightly. Be certain that the screws
are loose enough that you can lift the rack and remove it from
the screws through the larger part of the keyhole. If you want to
have the rack permanently attached, thread the screws tightly.
Placing the Optical Tube on the Dobsonian Base
Lift the optical tube and set the altitude bearings on either side
of the tube in the “cradle” of the base (Figure 5). The unique
flange design of the altitude bearing allows for automatic left-
to-right centering of the optical tube in the cradle. Once in the
cradle, the tube should pivot freely up and down with gentle
hand pressure. Note that the tube will not yet be properly bal-
anced, since the eyepiece and finder scope are not in place,
and the CorrecTension system has not been installed.
Installing the CorrecTension (XT) Friction
Optimization System
Perhaps the most exciting new feature of the SkyQuest XT10
Dobsonian is the CorrecTension Friction Optimization sys-
tem. Because of their relatively light weight, 10" and smaller
Dobsonians have always been plagued by insufficient friction
on the altitude bearing surfaces. As a result, such telescopes
move up and down much too freely. This causes problems
when the observer tries to accurately center and track an
object for viewing, especially at higher powers. Also, the tele-
scope becomes very sensitive to balance, requiring additional
equipment such as counterweight systems or adjustable side
bearings to compensate.
SkyQuest XT10 Dobsonians employ a simple yet effective
remedy for the friction problem that obviates the need for
such cumbersome countermeasures. CorrecTension Friction
Optimization utilizes a spring coil to “pull” the tube assem-
bly down onto the altitude bearing pads, thereby increasing
the friction by just the right amount. With CorrecTension, you
can change eyepieces or add a barlow lens without having to
tediously adjust the telescope’s balance as you would with other
Dobsonians. The altitude friction will roughly equal the azimuth
friction, ensuring optimal performance.
To install the CorrecTension assembly, follow these steps while
referring to Figure 6:
1. Put one of the black nylon spacers on a black Phillips head
screw. The spacer should be oriented so the narrow end
seats against the head of the screw. Slip one of the black
1/4" washers over the end of the screw. Now, thread the
screw into the hole in the base side panel just below the cra-
dle. The screw will thread into the preinstalled insert in the
hole. Use a Phillips screwdriver to tighten the screw. Repeat
this procedure on the opposite side panel.
Figure 4.
Using the two supplied screws, install the aluminum
eyepiece rack in the predrilled holes about halfway down the left side
panel of the base.
Figure 6.
Close-up view of the CorrecTension system.
Black nylon
spacers
1/4" washer
(black)
Altitude side bearing
Screw w/round knob
Spring
Phillips head
screw (black)
Pull loop
Figure 5.
Set the optical
tube on the “cradle” of the
base so that the altitude side
bearings on the tube rest on
the white plastic “pads.”