INSTRUCTION MANUAL
Orion®
™
Argonaut
150mm
Maksutov-Cassegrain
#9073 Optical Tube Assembly
#21480 With SkyView Deluxe Equatorial Mount
Congratulations on purchasing an Orion telescope! The Argonaut 150 is a precision instrument designed
for high-performance astronomical observation. With its Maksutov-Cassegrain optical system expertly
crafted in Russia, you’ll enjoy exquisite views of countless celestial objects. These instructions will help
you properly use and care for your telescope. Please read them over thoroughly before getting started.
Table of Contents
1. Parts List ................................................................................................................................................................. 2
2. Unpacking and Assembly........................................................................................................................................ 2
3. The Optics ............................................................................................................................................................... 2
4. Using the Telescope ................................................................................................................................................ 2
5. Care and Maintenance ............................................................................................................................................ 3
6. Specifications .......................................................................................................................................................... 4
7. Suggested Accessories .......................................................................................................................................... 4
Customer Support (800) 676-1343
E-mail: support@telescope.com
Corporate Offices (831) 763-7000
Providing Exceptional Consumer Optical Products Since 1975
P.O. Box 1815, Santa Cruz, CA 95061
IN 098 Rev. B 0499
1. Parts List
Qty. Description
1 Optical tube assembly (including 7x35 finder scope and
bracket, and carrying handle)
1 Dust cover
1 Padded case
If you purchased the #21480 package, the following items
should also be included (in separate packages):
1 1/4"-20 Adapter (#3800)
1 SkyView Deluxe equatorial mount and aluminum tripod
(#9400)
1 Extra counterweight (#9413)
2. Unpacking and Assembly
Exercise care when unpacking the shipping box. We recommend
keeping the original shipping box; in the event the telescope
needs to be shipped to another location or returned to Orion for
warranty repair, having the proper shipping container will help
ensure that your telescope will survive the journey intact.
The Argonaut 150 optical tube assembly has been preassembled and precollimated at the factory, so it should be
ready for use right out of the box.
3. The Optics
The Maksutov-Cassegrain optical design allows a long focal
length to be packed into a short optical tube. It employs a fixed
spherical primary mirror with a hole in the center through
which the light cone exits to the diagonal and eyepiece. A
spherical mirror of this aperture would, by itself, yield an unacceptable degree of spherical aberration, so the design
incorporates a deeply concave “corrector” lens, often called a
“meniscus,” at the front of the scope. This lens, at the center of
which the secondary mirror holder is mounted, provides sufficient correction to render a sharp, undistorted image.
The purplish tint of the meniscus is caused by multi-layer
coatings, which have been applied to the surfaces of the
glass to enhance light transmission and image contrast.
Cooling the Telescope
All optical instruments need time to reach “thermal equilibrium” to
achieve maximum stability of the lenses and mirrors, which is
essential for peak imaging performance. When moved from a
warm indoor location to cooler outdoor air, a telescope needs time
to equilibrate to the outdoor temperature. The bigger the instrument
and the larger the temperature change, the more time is needed.
For your Argonaut 150, allow at least one hour for temperature
equilibration. If the scope has to adjust to more than a 40° temperature differential, allow two to four hours. In the winter, storing
the telescope outdoors in an enclosed shed or garage greatly
reduces the amount of time needed for the optics to stabilize.
Collimation
The optical system was aligned (collimated) at the factory and
should not need adjustment. The collimation of the telescope
can be easily checked by doing a simple star test. This is
done by centering a bright star in the telescope and defocusing the image. Be sure to use a medium-high powered
eyepiece (15mm focal length or shorter) to do this. Also make
sure the star is well centered within the field of view. Defocus
the star image so it fills approximately 1/5 of the field of view.
What you should see is an image that resembles a doughnut.
If the “doughnut” looks round and the “hole” in the middle of it
is centered, then the telescope is properly collimated.
If the “doughnut hole” is not centered within the defocused
star image, then it must be recentered by adjusting the three
collimation screws on the front of the central obstruction; this
changes the tilt of the secondary mirror. Adjust one of the
screws by first loosening the other two screws, then tighten
the screw. Recenter the defocused star image within the
telescope’s field of view and see if the hole is now better centered. If not, adjust one of the other alignment screws in the
same fashion. Repeat this process until the “doughnut hole” is
centered in the out-of-focus star image.
If the outer edge of the defocused star image (the outer edge
of the “doughnut”) is not round, then one or more of the other
optical components (the primary mirror and meniscus lens)
may be out of collimation. If this is the case, the telescope will
need to be returned to the factory for adjustment. Please call
Orion Technical Support for further details
WARNING: Never look directly at the Sun
through your telescope or its finder scope—
even for an instant—without a professionally
made solar filter that completely covers the front
of the instrument, or permanent eye damage
could result. Be sure to also cover the front of
the finder scope with aluminum foil or another
opaque material to prevent physical damage to
the internal components of the scope itself as
well as to your eye. Young children should use
this telescope only with adult supervision.
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4. Using the Telescope
Your Orion Argonaut 150mm Maksutov-Cassegrain telescope yields
high-quality images, yet is very easy to use. You will be surprised at
the simplicity of operation and the exceptional optical performance.
To get the most out of your telescope, read this section carefully.
Required Accessories
The Argonaut 150 does not come with a star diagonal or
eyepiece, since many purchasers of this caliber of telescope
already have these accessories. The Argonaut 150 requires
either a 1.25" or 2" star diagonal. If you are planning on using
1.25" eyepieces, you must use a 1.25" diagonal (Orion
#8778). This will first require placing a 2"-to-1.25" adapter
(Orion #8768) directly into the Crayford focuser. The 1.25"
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 threaded mounting bolts. These are the mounting bolts found on
standard camera tripods. Camera tripods work fine for daytime 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"
diagonal into the focuser drawtube. Secure the diagonal with
the setscrew on the drawtube. Insert an eyepiece into the
diagonal 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
eyepiece. 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 alignment screws of the finder scope bracket will put the image
dead-center in the crosshairs. Otherwise, coarser adjustments 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 transportation 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 eyepiece, 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
practically 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 configuration, 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
(tighten 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.
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Any quality optical lens cleaning tissue and optical lens cleaning 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 glass cleaner or cleaning fluid designed for eyeglasses.
Always apply the fluid to the tissue, never directly on the optics.
After carefully cleaning the lens surface, gently wipe it with a dry
tissue, taking care not to rub too hard. Use lots of tissue on larger
lenses or if the lens surface has grease on it. If any tissue fibers
remain after wiping, use a blower bulb to blow them off. Repeat
the entire process if necessary. Don’t take any lenses apart for
cleaning!
With very little maintenance, your Argonaut 150mm MaksutovCassegrain will provide years of outstanding viewing. Enjoy!
6. Specifications
Optical system design: Maksutov-Cassegrain
Primary mirror diameter: 150mm (5.91")
Primary mirror composition: Pyrex, aluminized and overcoated
Primary mirror focal length: 1800mm
Focal ratio: f/12
Meniscus lens: BK-7 glass, multi-coated on both sides
Size of central obstruction: 50mm
Finder scope: 7x35 achromatic, 8° field of view
Tube length: 17 inches
Weight: 9.6 lbs.
7. Suggested Accessories
2"-to-1.25" Step-Down Adapter (#8768)—Allows use of
1.25" diagonals.
Star Diagonal, 1.25" (#8778)—Required for use of 1.25" eyepieces.
Star Diagonal, 2" (#8773)—Required for use of 2" eyepieces.
45° Erect-Image Diagonal, 1.25" (#8790)—Recommended
for daytime use of 1.25" eyepieces.
Orion Ultrascopic 1.25" Eyepieces—High-quality oculars at
a reasonable price.
Orion Optiluxe 2" Eyepieces—Long-focal-length eyepieces
that excel for deep-sky viewing. Fully multi-coated.
Camera Adapter (#5269)—Allows attachment of camera to
2" focuser, for through-the-telescope photography.
FlexiShield Dew Cap (#4208)—Helps prevent dew formation
on telescope’s front corrector lens.
Orion AccuTrack SVD Motor Drive (#7825)—For SkyView
Deluxe Equatorial Mount. Provides hands-free tracking for visual
use.
Orion DeepMap 600 (#4150)—Handy star chart and reference
guide.
Ultra Heavy Duty Bogen Tripod with Pan Head (#20709)—
Camera tripod recommended for terrestrial viewing.
Full-Aperture Glass Solar Filter (#7797)—Allows safe viewing of the Sun.
One-Year Limited Warranty
This Orion Argonaut 150mm Maksutov-Cassegrain is warranted against defects in materials or workmanship for a period of one year from the date of purchase. This warranty is for the benefit of the original retail
purchaser only. During this warranty period Orion Telescopes & Binoculars will repair or replace, at Orion’s
option, any warranted instrument that proves to be defective, provided it is returned postage paid to: Orion
Warranty Repair, 89 Hangar Way, Watsonville, CA 95076. If the product is not registered, proof of purchase
(such as a copy of the original invoice) is required.
This warranty does not apply if, in Orion’s judgment, the instrument has been abused,
mishandled, or modified, nor does it apply to normal wear and tear. This warranty gives you specific
legal rights, and you may also have other rights, which vary from state to state. For further warranty
service information, contact: Customer Service Department, Orion Telescopes & Binoculars, P. O.
Box 1815, Santa Cruz, CA 95061; (800) 676-1343.
Orion Telescopes & Binoculars
Post Office Box 1815, Santa Cruz, CA 95061
Customer Support Help Line (800) 676-1343 • Day or Evening
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