
INSTRUCTION MANUAL
IN 162 Rev. B 03/02
Providing Exceptional Consumer Optical Products Since 1975
Customer Support (800) 676-1343
E-mail: support@telescope.com
Corporate Offices (831) 763-7000
P.O. Box 1815, Santa Cruz, CA 95061
Orion
®
StarMax
™
90 EQ
#9821 Equatorial Maksutov-Cassegrain Telescope

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Figure 1. Orion StarMax 90mm EQ
Mounting block
Counterweight shaft
Right Ascension
slow-motion control
Counterweight
Counterweight lock knob
Tripod leg
Finder scope bracket
Finder scope
Eyepiece
Star diagonal
Declination
slow motion control
Accessory tray
Accessory tray bracket
Leg lock knob

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1. Unpacking
The entire telescope system will arrive in one box.Be careful
unpacking the box.We recommend keeping the original shipping container. In the event that 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.
Make sure all the parts in the Parts List are present. Be sure
to check box carefully, as some parts are small. If anything
appears to be missing or broken, immediately call Orion
Customer Support (800-676-1343) or email suppor t@telescope.com for assistance.
2. Parts List
Qty. Description
1 Optical tube assembly
1 Optical tube dust cover
1 25mm (50x) Sirius Plössl eyepiece (1.25")
1 Mirror star diagonal
1 6x20 correct-image finder scope
1 Dovetail finder scope bracket
1 Equatorial mount
3 Tripod legs
1 Counterweight shaft
1 Counterweight
1 Tripod accessory tray
1 Accessory tray bracket
2 Slow-motion control cables
1 1/4"-20 adapter
Welcome to a new world of adventure. Your new StarMax 90mm EQ is designed for high-resolution
observing of astronomical objects, and can also be used for terrestrial exploration. With its precision
optics and equatorial mount, you’ll be able to locate and enjoy hundreds of fascinating celestial objects,
including the planets, Moon, and a variety of deep-sky galaxies, nebulas, and star clusters.
If you have never owned a telescope before, we would like to welcome you to amateur astronomy.Take
some time to familiarize yourself with the night sky. Learn to recognize the patterns of stars in the major
constellations. With a little practice, a little patience, and a reasonably dark sky away from city lights,
you’ll find your telescope to be a never-ending source of wonder, exploration, and relaxation.
These instructions will help you set up, properly use and care for your telescope. Please read them over
thoroughly before getting started.
Table of Contents
1. Unpacking................................................................................................................................3
2. Parts List..................................................................................................................................3
3. Assembly.................................................................................................................................4
4. Getting Started ........................................................................................................................5
5. Setting Up and Using the Equatorial Mount ............................................................................6
6. Using Y our T elescope—Astronomical Observing.....................................................................9
7. Terrestrial Viewing..................................................................................................................12
8. Photography...........................................................................................................................12
9. Care and Maintenance ..........................................................................................................12
10. Specifications.........................................................................................................................13
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.Young children should use
this telescope only with adult supervision.

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1 Soft carry case
3 Assembly tools (small wrench, Phillips head
screwdriver, triangular assembly tool)
3 Leg attachment screws
3 Leg lock knobs
3. Assembly
1. Lay the equatorial mount on its side. Attach the tripod
legs, one at a time, to the base of the mount by sliding a
tripod leg attachment screw through the top of a leg and
through the holes in the base of the mount.The washers
should be on the outside of the tripod legs. Secure the
wing nuts finger-tight.Note that the accessory tray bracket attachment point on each leg should face inward.
2. Install and tighten the leg lock knobs on the bottom
braces of the tripod legs. For now, keep the legs at their
shortest (fully retracted) length; you can extend them to a
more desirable length later, after the tripod is completely
assembled.
3. With the tripod legs now attached to the mount, stand the
tripod upright (be careful!) and spread the legs apart
enough to connect each end of the accessory tray bracket to the attachment point on each leg.Use the screw and
lock nut that come installed in each attachment point to
do this.First, remove the screw using the supplied scre wdriver and triangular assembly tool; hold the lock nut with
the triangular assembly tool while turning the screw with
the screwdriver. Then, line up one of the ends of the
bracket with the attachment point and reinstall the screw.
4. Now, with the accessory tray bracket attached, spread
the tripod legs apart as far as they will go, until the bracket is taut. Connect the accessory tray to the accessory
tray bracket with the three wing screws already installed
in the tray. This is done by pushing the wing screws up
through the holes in the accessory tray bracket and
threading them into the holes in the accessory tray.
5. Tighten the screws at the tops of the tripod legs, so the
legs are securely fastened to the mount. Use the provided screwdriver and your fingers to do this.
6. Orient the equatorial mount as it appears in Figure 2, at a
latitude of about 40°, i.e., so the pointer next to the latitude scale (located directly above the latitude lock t-bolt)
is pointing to the hash mark at “40.” To do this, loosen the
latitude lock t-bolt, and turn the latitude adjustment t-bolt
until the pointer and the “40” line up. Then retighten the
Figure 2
Right ascension setting circle
Declination
slow motion control
Latitude scale
Latitude adjusting T-Bolt
Latitude locking T-Bolt
Declination lock knob
(not shown)
Declination setting circle
Right ascension
lock knob
Right Ascension slow
motion control
D
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(
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Right ascension
(R.A.) axis

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latitude lock t-bolt.The declination (Dec.) and right ascension (R.A.) axes may need re-positioning (rotation) as
well. Be sure to loosen the R.A. and Dec. lock knobs
before doing this.Retighten the R.A.and Dec. lock knobs
once the equatorial mount is properly oriented.
7. Thread the counterweight shaft into the equatorial mount
at the base of the declination axis until tight.
8. Remove the screw and washer on the bottom of the counterweight shaft and slide the counterweight onto the
shaft. Make sure the counterweight lock knobs are adequately loosened to allow the counterweight shaft to pass
through the hole. Position the counterweight about
halfway up the shaft and tighten the lock knobs. Replace
the screw and washer on the counterweight shaft.
9. Attach the 1/4"-20 adapter to the top of the equatorial
mount using the bolts and washers that come with the
adapter. Push the bolts, with washers attached, up
through the holes in the top of the mount and thread them
into the bottom of the adapter.Tighten the bolts securely
with the supplied wrench.
10. Connect the optical tube assembly to the 1/4"-20 adapter
on the mount by threading the adapter’s shaft into the
hole in the optical tube’s mounting block. Or ient the optical tube so that it is parallel to the length of the adapter,
as it is in Figure 1.Tighten this connection firmly by rotating the knurled thumb wheel on the adapter
counter-clockwise.
11. Now attach the two slow-motion cables to the R.A. and
Dec. slow-motion shafts of the equatorial mount by positioning the thumbscrew on the end of the cable over the
indented slot on the shaft, then tightening the thumb
screw. A cable can be attached to either end of the R.A.
shaft, whichever is most convenient for you. Use the
shorter cable for the R.A.shaft.
12. To place the finder scope in its bracket, first remove the
O-ring from the finder scope bracket. Loosen the three
nylon thumbscrews on the bracket until the tips of the
screws are flush with the inside of the bracket.Insert the
objective end (the end without the rubber eyeguard) of
the finder scope into the bracket ring with the three nylon
thumbscrews.When the finder scope is through the second ring of the bracket and as far as it will go, push the
O-Ring on the objective end of the finder scope and set it
about 1" down the finder scope tube.Then pull the finder
scope back gently until the O-Ring seats itself on the
ridge inside the second ring of the finder scope bracket.
Tighten the three nylon screws equally until they are
touching the sides of the finder scope.
13. Insert the base of the finder scope bracket into the dovetail holder on the optical tube. Lock the bracket into
position by tightening the knurled thumbscrew on the
dovetail holder.
14. Remove the cap from the eyepiece adapter on the rear of
the optical tube and insert the chrome barrel of the mirror
star diagonal. Secure the diagonal with the thumbscrews
on the eyepiece adapter.
15. Now, insert the chrome barrel of the 25mm eyepiece into
the star diagonal. Secure the eyepiece with the thumbscrews on the star diagonal.
The telescope system is now fully assembled. Keep the dust
cover ov er the front end of the telescope when it is not in use .
It is also a good idea to cover the ey epiece;use the cover cap
that came with it.
4. Getting Started
Balancing the Telescope
To insure smooth movement of the telescope on both axes of
motion (R.A. and Dec.) of the equatorial mount, it is imperative that the optical tube be properly balanced.
1.Keeping one hand on the telescope optical tube, loosen the
R.A. lock knob. Make sure the Dec. lock knob is locked.The
telescope should now be able to rotate freely about the R.A.
axis. Rotate it until the counterweight shaft is parallel to the
ground (i.e., horizontal).
2. Now loosen the counterweight lock knob and slide the
weight along the shaft until it exactly counterbalances the telescope (Figure 3a). That’s the point at which the shaft
Figure 3: Proper operation of the equatorial mount
requires balancing the telescope tube on the R.A. axis.
(a) With the R.A. lock knob released, slide the
counterweight along the counterweight shaft until it
just counterbalances the tube. (b) When you let go with
both hands, the tube should not drift up or down.
a.
b.