8
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 -
the top of a telephone pole, a chimney, etc. Position that
object in the center of the telescope’s eyepiece.
Now, look in the finder scope. Is the object visible? Ideally, it
will be somewhere in the field of view. If it is not, some coarse
adjustments of the six finder scope alignment thumb screws
will be needed to get the finder scope roughly parallel to the
main tube.
NOTE: The image in both the finder scope and the main tele-
scope will appear upside-down (rotated 180°). This is normal
for finder scopes and reflector telescopes (see Figure 11).
With the image in the finder scope’s field of view, you will now
use the six alignment thumb screws to center the object on
the intersection of the crosshairs.
By loosening one alignment thumb screw and tightening anoth-
er, you change the line of sight of the finder scope. The round,
knurled lock nuts installed on the alignment thumb screws must
be adequately loosened to allow the thumb screws to be
threaded in or out. Continue making adjustments to the various
alignment thumb screws until the image in both the finder
scope and the telescope’s eyepiece is 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. Once the finder scope is
aligned, turn the lock nuts clockwise until finger-tight to secure
the alignment thumb screws in place.
The finder scope alignment needs to be checked before every
observing session. This can easily be done at night, before
viewing through the telescope. Choose any bright star or plan-
et, 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
If, when looking through the finder scope, the images appear
somewhat out of focus, you will need to refocus the finder
scope for your eyes. Loosen the lock ring located behind the
objective lens cell on the body of the finder scope (see Figure
8). Back the lock ring off by a few turns, for now. Refocus the
finder scope on a distant object by threading the objective
lens cell in or out on the finder scope body. Precise focusing
will be achieved by focusing the finder scope on a bright star.
Once the image appears sharp, retighten the lock ring behind
the objective lens cell. The finder scope’s focus should not
need to be adjusted again.
Aiming/Pointing the Telescope
With the finder scope aligned, the telescope can be quickly
and accurately pointed at anything you wish to observe. The
finder scope has a much wider field of view than the tele-
scope’s eyepiece, and therefore it is much easier to first
center an object in the finder scope. Then, if the finder scope
is accurately aligned, the object will also be centered in the
telescope’s field of view.
Start by once again moving the telescope until it is pointed in
the general direction of the object you want to see. Some
observers find it convenient to sight along the tube to do this.
Now, look in the finder scope. If your general aim is accurate,
the object should appear somewhere in the field of view.
Make small adjustments to the telescope’s position until the
object is centered on the finder’s crosshairs. Now, look in the
telescope’s eyepiece and enjoy the view!
Magnification
Now that the object you want to view is well centered in the
25mm eyepiece, you may want to increase the magnification
to get a closer view. Loosen the thumb screw on the 1.25"
eyepiece adapter and remove the eyepiece. Place it in the
eyepiece rack, if you wish. Insert the 9mm eyepiece into the
1.25" eyepiece adapter, then retighten the thumb screw. If you
were careful not to bump the telescope, the object should still
be centered within the field of view. Notice that the object
being viewed is now larger, but somewhat dimmer.
The SkyQuest XT10 is designed to accept any eyepiece with
a barrel diameter of 1.25" or 2". Magnification, or power, is
determined by the focal length of the telescope and the focal
Naked-eye view
Figure 11. The view through a standard finder scope and reflector
telescope is upside down. This is true for the SkyQuest and its finder
scope as well.
View through finder scope and telescope
