Care And Maintenance - Orion Argonaut 150mm 9073 Instruction Manual

eyepieces will not reach focus if used in the 2" diagonal. If you
wish to use 2" eyepieces, you must additionally purchase a 2"
star diagonal (Orion #8773).
For terrestrial (daytime) use, we recommend the 1.25" 45°
correct image diagonal (Orion #8790).
Mounting Options
If you have purchased the #21480 package, then you already
have an equatorial mount to use with your Argonaut 150.
Refer to the instructions that come with the SkyView Deluxe
Equatorial Mount and the 1/4"-20 Adapter to assemble the
mount and connect the telescope.
Another excellent mount for the Argonaut 150 tube assembly is the
Vixen Great Polaris (GP) Equatorial Mount (Orion item #9245).
The Argonaut 150 has a mounting plate on the underside of
its optical tube that accepts both 1/4"-20 and 3/8"-16 thread-
ed mounting bolts. These are the mounting bolts found on
standard camera tripods. Camera tripods work fine for day-
time usage, but do not work well for pointing the telescope
upward for astronomical viewing. For astronomy we highly
recommend a sturdy equatorial mount. The telescope can be
attached to an equatorial mount by either the mounting plate
on the optical tube, or by tube rings (purchased separately).
Focusing the Telescope
The Argonaut 150 is equipped with a Crayford-type focuser
that smoothly moves the focuser drawtube in and out. Insert
either a 1.25" diagonal with a 2"-to-1.25" adapter or a 2" diag-
onal into the focuser drawtube. Secure the diagonal with the
setscrew on the drawtube. Insert an eyepiece into the diago-
nal and secure it with the thumbscrew.
To test the focusing procedure, look through the eyepiece and find
a bright star or a land object over a quarter-mile away. Center it in
the field of view. Now, using your fingers, slowly rotate one of the
focusing knobs until the object comes into sharp focus.
There are two setscrews on the underside of the focuser. The
one that is nearest to the drawtube (farthest back) adjusts the
tension of the focus knob against the focuser drawtube. Tighten
this setscrew finger-tight so the drawtube moves in and out
smoothly when the focus knob is rotated. This setscrew may
need to be readjusted when changing to a heavier or lighter eye-
piece. The front setscrew locks the focuser drawtube in place.
Aligning the Finder Scope
The finder scope and the telescope should be aligned to point
to exactly the same spot in the sky. Alignment is easiest to do
in daylight hours, before your observing session. Choose a
treetop, telephone pole, street sign—anything that is far off in
the distance, at least a quarter-mile away. Put that image in
the center of the field of your telescope's eyepiece. Where is
it in your finder scope's eyepiece? Hopefully, the image will be
in the field of view and some simple adjustments on the align-
ment screws of the finder scope bracket will put the image
dead-center in the crosshairs. Otherwise, coarser adjust-
ments to the alignment screws will be necessary. Focus the
finder scope by rotating its eyepiece assembly.
By loosening one alignment screw and tightening another, you
can change the line of sight of the finder scope. Continue making
adjustments to the alignment screws until the image in both the
finder scope and the telescope's eyepiece are exactly centered.
Check the alignment by moving the scope 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.
Finder scopes often come out of alignment during trans-
portation of the telescope from site to site, so check the
alignment before each observing session.
Eyepiece Selection
Always start viewing with your lowest-power, widest-field eyepiece.
After you've located and looked at the object with a low-power eye-
piece, switch to a higher-power eyepiece and see if the object
looks better or worse. Keep in mind that at higher power, an image
will always be fainter and less sharp (this is a fundamental law of
optics). Many observers use the lowest-power eyepiece practical-
ly all the time! Naturally, higher magnifications are desirable for
viewing some celestial objects, but stay with low powers when
searching for an object and for extended viewing.
To calculate the power, or magnification of a telescope, divide the
focal length of the telescope by the focal length of the eyepiece.
Telescope f.l. ÷ Eyepiece f.l. = Magnification
For example, with the Argonaut 150, which has a focal length
of 1800mm, and a 25mm eyepiece, the power would be
1800 ÷ 25 = 72x.
We recommend having a selection of three to six eyepieces
of different focal lengths, so that you can choose the optimal
magnification, brightness level, and contrast for each object
and for different observing conditions.
Attaching a Camera for Photography
A 35mm single-lens reflex (SLR) camera body can be
attached to the back of the Argonaut 150, enabling you to take
pictures through the telescope. When used in this configura-
tion, the telescope acts as a 1800mm telephoto lens (the focal
length of the telescope). All that is needed is a camera adapter
(Orion item #5269) and a T-ring, which is specific to your
model of camera (see the Orion catalog for selection).
Remove the eyepiece and diagonal from the telescope optical
tube. Also remove the lens from your camera body. Connect
the T-ring to your camera. Then thread the T-ring, with your
camera attached, onto the camera adapter. The 2" barrel end
of the camera adapter seats into the telescope's focuser (tight-
en the setscrew!). You are now ready to take a picture.

5. Care and Maintenance

Give your telescope reasonable care and it will last a lifetime.
Store it indoors or in a dry garage. When the telescope is not
in use, keep it in its padded case with the dust covers in place.
Any quality optical lens cleaning tissue and optical lens clean-
ing fluid specifically designed for multi-coated optics can be
used to clean the front corrector lens of the telescope and exposed
lenses of your eyepieces and finder scope. Never use regular
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