Parts List; Unpacking And Assembly; The Optics; Using The Telescope - Orion Argonaut 150mm 9073 Instruction Manual

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)
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.

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 pre-
assembled 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 unac-
ceptable 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 suffi-
cient 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.
2
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° tem-
perature 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 tele-
scope can be easily checked by doing a simple star test. This
is done by centering a bright star in the telescope and defo-
cusing 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 tele-
scope'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

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 eye-
piece, 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"