Orion ATLAS 10 EQ 9874 - Manual (Page 6)

5. using Your telescope
Focusing the telescope
With the 25mm eyepiece inserted in the focuser, loosen the
R.A. and Dec.lock levers and 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.
NOTE: The image in the telescope will appear rotated
180° (upside down and reversed left-to-right). This is nor-
mal for astronomical scopes. The finder scope view will
also be rotated 180° (see Figure 6).
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.
The black nylon thumbscrew on the top of the body of the
focuser (see Figure 4) will lock the focuser drawtube in place
once the telescope is properly focused. Before focusing,
remember to first loosen this thumbscrew.
Viewing with Eyeglasses
If you wear eyeglasses, you may able to keep them on while
you observe, if the eyepiece has 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 re‑focusing 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 Atlas 10 EQ Deluxe comes with a 9x50 achromatic finder
scope (Figure 3a). The number 9 means six‑times magnifica‑
tion and the 50 indicates a 50mm diameter front lens. The
finder scope makes it easier to locate the object you want
to observe in the telescope, because the finder scope has a
much wider field‑of‑view.
The Atlas 10 EQ’s finder scope uses a spring‑loaded bracket
that makes alignment of the finderscope very easy. As you
turn either of the thumbscrews, the spring in the bracket’s ten‑
sioner moves in and out to keep the finder scope secure in
the bracket.
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 a 1/4 mile away—
the top of a telephone pole, a chimney, etc. Loosen the R.A.
and Dec. lock levers and move the telescope until it is pointing
toward the desired object. Then sight along the tube to pre‑
cisely aim the telescope. Turn the focus knob until the object
is properly focused. Retighten the lock levers.
Now look in the finder scope. Is the object visible? Ideally it
will be somewhere in the field of view. If not, some coarse
adjustment to the finder scope bracket’s alignment thumb‑
screws will be needed until the object comes into the finder
scope’s field of view.
With the image in the finder scope’s field of view, you now
need to fine‑adjust the alignment thumbscrews to center the
object on the intersection of the crosshairs. Adjust the aim of
the finder scope by turning the thumbscrews, one at a time,
until the object is centered.
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 planet, center the object in telescope eyepiece, and then
adjust the finder scope bracket’s alignment thumbscrews until
the star or planet is centered on the finder’s crosshairs.
Focusing the finder scope
If, when you look 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
3a). Back the lock ring off by a few turns, for now. Refocus
the finder scope on a distant object by threading the objec‑
tive lens cell in or out of the finderscope body. Precise focus‑
ing will be achieved by focusing the finder scope on a bright
star. Once the image appears sharp, retighten the locking ring
behind the objective lens cell. The finder scope’s focus should
not need to be adjusted again.
Magnification & Eyepieces
Magnification, or power, is determined by the focal length of
the telescope and the focal length of the eyepiece. Therefore,
by using eyepieces of different focal lengths, the resultant
magnification can be varied.
Magnification is calculated as follows:
Telescope Focal Length (mm)
= Magnification
Eyepiece Focal Length (mm)
6
Naked‑eye view
View through finder scope and telescope
Figure 6. The view through a standard finder scope and reflector
telescope is rotated 180°. This is true for the Atlas 10 EQ and its
finder scope as well.