Focusing The Telescope; Aligning The Finder Scope - Orion 10026 XT6i Instruction Manual

Focusing the telescope

With the 25mm Sirius Plössl eyepiece in the focuser and
secured with the thumbscrew(s), 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 eyepiece
while slowly rotating the focusing knob in the opposite direction.
You should soon see the point at which focus is reached.
For XT8i, XT10i and XT12i models, the focus lock thumb
screw on the bottom of the focuser body (Figure 13a) will
lock the focuser drawtube in place once the telescope is prop-
erly focused. The XT6i's focus lock thumb screw is located
on the top of the focuser body (Figure 13b). Before focusing,
remember to first loosen the focus lock thumb screw. Do not
loosen the thumb screw too much as there must be some ten-
sion 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. On the XT8i,
XT10i, and XT12i, the focusing tension adjustment set screw
is a 3mm socket head set screw located below the focus lock
thumb screw (Figure 13a). A 3mm hex key is required for
adjustment of focus tension. On the XT6i, the focusing ten-
sion adjustment set screws are the two small set screws
located on either side of the focus lock thumb screw (Figure
13b). A 1.5mm hex key is required to adjust the focus tension
on the XT6i. Due to the rack-and-pinion focuser design on the
XT6, tension adjustment should not normally be needed as it
has been pre-adjusted at the factory.
Viewing with Eyeglasses
If you wear eyeglasses, you may be able to keep them on
while you observe, if your eyepieces have enough eye relief
to allow you to see the whole field of view. You can try this by
looking through the eyepiece first with your glasses on and
then with them off, and see if the glasses restrict the view
to only a portion of the full field. If they do, you can easily
observe with your glasses off by just refocusing the telescope
the needed amount. If you suffer from severe astigmatism,
however, you may find images noticeably sharper with your
glasses on.

aligning the Finder scope

The finder scope must be aligned accurately with the tele-
scope for proper use. To align it, first aim the main telescope
in the general direction of an object at least 1/4-mile away,
e.g., the top of a telephone pole, a chimney, etc. Position that
object in the center of the telescope's eyepiece.
The finder scope uses a spring-loaded bracket that makes
alignment of the finderscope very easy. As you turn either
12
Naked-eye view
View through telescope
Figure 16.
The view through a reflector telescope is upside
down. This is true for the SkyQuest XT IntelliScope.
of the thumbscrews, the spring in the bracket's tensioning
pin moves in and out to keep the finder scope secure in the
bracket.
Note: The image in the main telescope will appear
upside-down (rotated 180°). This is normal for reflector
telescopes (see Figure 16).
Now look through the finder scope. Ideally, the object should
be within the field of view. If not, then coarse adjustments to
the alignment thumbscrews will be needed. Once the image
is in the finder scope's field of view, you will now use the align-
ment thumbscrews to center the object on the intersection of
the crosshairs. By loosening one alignment thumbscrew, you
change the line of sight of the finder scope. Continue making
adjustments to the alignment thumbscrews until the image
in both the finder scope and the telescope's eyepiece are
exactly centered.
Check the alignment by moving the telescope to another
object and fixing the finder scope's crosshairs on the exact
point you want to look at. Then look through the telescope's
eyepiece to see if that point is centered in the field of view. If
it is, the job is done. If not, make the necessary adjustments
until the two images match up.
The finder scope alignment should be checked before every
observing session. This can easily be done at night, before
viewing through the telescope. Choose any bright star or
planet, center the object in the telescope eyepiece, and then
adjust the finder scope's alignment thumb screws until the
star or planet is also centered on the finder's crosshairs. The
finder scope is an invaluable tool for locating objects in the
night sky; its usage for this purpose will be discussed later.
Focusing the Finder scope
The finder scope with your SkyQuest IntelliScope has adjust-
able focus. If the images in the finder appear somewhat out