Focusing The Telescope; Using Your Telescope - Orion SkyQuest XT10 Classic Instruction Manual

2" eyepiece adapter
Figure 9.
The 2" Crayford focuser with eyepiece adapters
attached. the focuser will accept eyepieces with barrel diameters of
1.25" and 2".
screw on the 1.25" eyepiece adapter. The other eyepiece can
be placed in the eyepiece rack until it is needed.
The assembly of your SkyQuest Dobsonian is now complete.
It should appear as shown in Figure 1. The dust cover on the
front of the telescope tube should always remain in place
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. Using Your Telescope

It is best to get a feel for the basic functions of the SkyQuest
XT10 Dobsonian during the day, before observing astro-
nomical objects at night. This way you will not have to fumble
around trying to orient yourself in the dark! Find a spot out-
doors where you have plenty of room to move around the
telescope, and where you have a clear view of some object
or vista that is at least 1/4-mile away. It is not critical that the
base be exactly level, but it should be placed on somewhat
flat ground or pavement 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 XT10 permits motion
of the telescope along two axes: altitude (up/down) and azi-
muth (left/right) (see Figure 10). 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.
1.25" eyepiece
adapter
Focus lock
thumbscrew
Tension adjustment screw
Altitude
Figure 10.
The SkyQuest has two axes of motion: altitude (up/
down) and azimuth (left/right).

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 located on the bottom of the focuser body
(Figure 9) will lock the focuser drawtube in place once the
telescope is properly focused. Before focusing, remember
to first loosen the focus lock thumb screw. Do not loosen the
thumb screw too much as there must be some tension to
keep the drawtube secure within the focuser.
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 or drawtube moves inward by itself), the ten-
sion can be adjusted for optimal performance. The focusing
tension adjustment set screw is a 3mm socket head set
screw located below the focus lock thumb screw (Figure 9).
A 3mm hex key is required for adjustment of focus tension.
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 eyerelief 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
Azimuth
7