Orion 120 EQ User Manual

INSTRUCTION MANUAL

Orion®

SkyView™ Pro 120 EQ

#9867 Equatorial Refractor Telescope

Providing Exceptional Consumer Optical Products Since 1975

Customer Support (800)-676-1343
E-mail: [e-mail]

Corporate Offices (831)-763-7000

89 Hangar Way, Watsonville, CA 95076

IN 189 Rev. C 02/09

Objective lens

Declination lock lever
(opposite side)

Right Ascension lock lever
(opposite side)

Optical tube

Tube rings

Finder scope

Declination slow-motion
control knob

Safety thumbscrew

Mounting plate securing knob

Counterweight shaft

Counterweights

Counterweight lock knobs

Tripod leg

Finder scope bracket

Eyepiece

Star diagonal

Focus wheel

Right Ascension
slow-motion control knob

Latitude scale

Latitude adjustment L-bolts

Center support shaft

Tripod support tray

Leg lock knobs

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Figure 1. The SkyView Pro 120 EQ.

Congratulations on your purchase of an Orion telescope. Your new SkyView Pro 120 EQ is designed

®

for high-resolution viewing and astrophotography of astronomical objects. With its precision optics and
sturdy equatorial mount, you’ll be able to enjoy hundreds of fascinating celestial denizens.

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 ............................ 3

4. Balancing the Telescope ................. 5

5. Using Your Telescope ................... 6

6. Setting Up and Using the Equatorial Mount . . 7

7. Astronomical Observing ................ 12

8. Astrophotography ..................... 15

9. Collimating (Aligning the Optics).......... 16

10. Care and Maintenance ................ 16

11. Specifications ....................... 17

1. Unpacking

The SkyView Pro 120 EQ will arrive in one box. Be careful
unpacking the box. We recommend keeping the box and all
original packaging. In the event that the telescope needs to be
shipped to another location, or returned to Orion for warranty
repair, having the proper box and packaging 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 each box carefully, as some parts are small.
If anything appears to be missing or broken, immediate­ly call Orion Customer Suppor t (800-676-1343) or email
[e-mail] for assistance.

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.

2. Parts List

1 Optical tube assembly

1 Tripod

1 Equatorial mount

1 Tripod support tray

1 Counterweight shaft

1 Large counterweight

1 Small counterweight

2 Slow-motion control knobs

1 R.A. axis rear cover

1 Latitude adjustment L-bolt

2 Tube rings with mounting screws

1 Tube ring mounting plate

1 25mm Sirius Plössl eyepiece

1 10mm Sirius Plössl eyepiece

1 Star diagonal

1 Finder scope

1 Finder scope bracket with O-ring

1 Dust cover

1 Collimation tool

3. Assembly

Assembling the telescope for the first time should take about
30 minutes. No tools are needed other than the ones provided.
All screws should be tightened securely, but be careful not to
over-tighten or the threads may strip. Refer to Figure 1 during
the assembly process.

During assembly (and anytime, for that matter), do not touch
the surfaces of the lenses of the telescope, finder scope or
eyepieces with your fingers. The optical surfaces have delicate
coatings on them that can easily be damaged if touched inap­propriately. Never remove any lens assembly from its housing
for any reason, or the product warranty and return policy will
be voided.

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Finder scope bracket Nylon

Finder scope

alignment
thumbscrews

Azimuth
adjustment
knobs

Figure 2. Orient the equatorial mount so that the post on the

tripod head lines up between the azimuth adjustment knobs on the
equatorial mount.

1. Stand the tripod legs upright and spread the legs out as far
as they will go. Keep the tripod legs at their shortest (fully
retracted) length, for now; you can extend them to a more
desirable length later, after the scope is fully assembled.

2. Place the base of the equatorial mount onto the tripod
head. Orient the equatorial mount so that the post on
the tripod head lines up between the azimuth adjustment
knobs on the equatorial mount (Figure 2). You may need
to loosen the azimuth adjustment knobs on the equatorial
mount in order to fit the mount into the tripod head.

3. Thread the central support shaft into the equatorial mount
until tight. This will secure the equatorial mount to the tri­pod head.

4. Remove the knob and washer from the bottom of the center
support shaft. Slide the tripod support tray up the bottom
of the central support shaft until the three tray arms are
touching the legs of the tripod. The flat side of the acces­sory tray should be facing up. Make sure the “V” of each
tray arm is against a tripod leg. Place the washer back on
the center support shaft against the tray, and thread the
securing knob all the way up the center support shaft until
it is tight against the tray. The tripod support tray provides
additional stability for the tripod, and holds five 1.25" eye­pieces and two 2" eyepieces.

5. Thread the latitude adjustment L-bolt into the rear of the
equatorial mount casing as shown in Figure 1.

6. Thread the counterweight shaft into the equatorial mount
at the base of the declination axis until tight. Make sure the
casting at the top of the shaft is threaded clockwise as far
as it will go before attaching the shaft. Once the shaft is
installed, turn the casting counter-clockwise until the top of
the casting is flush with the mount.

7. Remove the knurled “toe saver” retaining screw on the
bottom of the counterweight shaft and slide both counter­weights onto the shaft. Make sure the counterweight lock
knobs are adequately loosened to allow the counterweight
shaft to pass through the hole. Position the counterweights

Post

Tensioner

Focus lock ring

Figure 3a. The 8x40 finder scope.

Figure 3b. Pull-back on the tensioner and slide the finder scope

into its bracket until the O-ring is seated in the bracket ring.

about halfway up the shaft and tighten the lock knobs.
Replace the toe saver at the end of the bar. The toe saver
prevents the counterweights from falling on your foot if the
lock knobs happen to come loose.

8. Attach the slow-motion control knobs to the right ascen­sion and declination worm gear shafts of the equatorial
mount by sliding them onto the shafts. Line up the flat on
the end of the shaft with the corresponding feature on the
interior of the knob to attach them properly. The knobs can
be attached to either end of the shafts; use whichever end
is most convenient.

9. Attach the tube rings to the tube ring mounting plate using
the attachment screws that are on the tube rings. The
screws should go through the holes on the outer ends of

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®

a b c d

Figure 4a - 4d. Proper operation of the equatorial mount requires that the telescope tube be balanced on both the R.A. and Dec. axes.

(a) With the R.A. lock lever 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. (c) With the Dec. lock lever released, loosen the tube ring lock clamps a few
turns and slide the telescope forward or back in the tube rings. (d) When the tube is balanced about the Dec. axis, it will not move when you
let go.

the mounting plate and rethread into the tube rings. Note
that the side of the mounting plate with the central “groove”
will be facing up. Use the small wrench to secure the tube
rings to the mounting plate.

10. Loosen the black mounting plate securing knob as well as
the metal safety thumbscrew on the top of the equatorial
mount. Place the mounting plate, with tube rings attached,
in the dovetail slot on top of the equatorial mount. Position
the mounting plate so that it is centered on the dovetail
slot. Re-tighten the mounting plate securing knob until the
mounting plate is secure. Then, tighten the safety thumb­screw. The safety thumbscrew will ensure that the mount­ing plate (and telescope tube) will not fall off the EQ mount
if the mounting plate securing knob should come loose.

11. Open the tube rings and lay the telescope optical tube in
the rings at about the midpoint of the tube’s length. Rotate
the tube so that the focuser is at a convenient position for
viewing. Close the tube rings and tighten them.

Installing the Finder Scope

To place the finder scope (Figure 3a) in the finder scope brack­et, unthread the two black nylon screws until the screw ends
are flush with the inside diameter of the bracket. Place the
O-ring that comes on the base of the bracket over the body
of the finder scope until it seats into the slot on the middle of
the finder scope. Slide the eyepiece end (narrow end) of the
finder scope into the end of the bracket’s cylinder opposite the
adjustment screws while pulling the chrome, spring-loaded
tensioner on the bracket with your fingers (Figure 3b). Push
the finder scope through the bracket until the O-ring seats just
inside the front opening of the bracket cylinder. Release the
tensioner and tighten the two black nylon screws a couple of
turns each to secure the finder scope in place. Insert the base
of the finder scope bracket into the dovetail holder on the top
of the focuser. Lock the bracket into position by tightening the
knurled thumbscrew on the dovetail holder.

Inserting the Diagonal and Eyepiece

Loosen the thumbscrew on the 1.25" adapter on the focuser
and remove the small dust cap. Insert the chrome barrel of
the star diagonal into the focuser and secure with the thumb­screw. Loosen the thumbscrews on the diagonal and insert

the 25mm eyepiece into the focuser and secure it with the
thumbscrews.

Your telescope is now completely assembled and should
appear as shown in Figure 1.

4. Balancing the Telescope

To ensure smooth movement of the telescope on both axes
of the equatorial mount, it is imperative that the optical tube
is properly balanced. We will first balance the telescope with
respect to the right ascension (R.A.) axis, then the declination
(Dec.) axis.

1. Keeping one hand on the telescope optical tube, loosen
the R.A. lock lever. Make sure the Dec. lock lever is locked,
for now. The telescope should now be able to rotate freely
about the right ascension axis. Rotate it until the counter­weight shaft is parallel to the ground (i.e., horizontal).

2. Now loosen both counterweight lock knobs and slide the
weights along the shaft until they exactly counterbalance
the telescope (Figure 4a). That’s the point at which the
shaft remains horizontal even when you let go with both
hands (Figure 4b).

3. Retighten the counterweight lock knobs. The telescope is
now balanced on the right ascension axis.

4. To balance the telescope on the declination axis, first tight­en the R.A. lock lever, with the counterweight shaft still in
the horizontal position.

5. With one hand on the telescope optical tube, loosen the
Dec. lock lever. The telescope should now be able to rotate
freely about the Dec. axis. Loosen the tube ring clamps a
few turns, until you can slide the telescope tube forward
and back inside the rings. (this can be aided by using a
slight twisting motion on the optical tube while you push or
pull on it) (Figure 4c).

6. Position the telescope in the mounting rings so it remains
horizontal when you carefully let go with both hands. This
is the balance point for the optical tube with respect to the
Dec. axis (Figure 4d). If the optical tube does move, then
you must adjust the position of the optical tube in the tube
rings until it does balance in the declination axis.

7. Retighten the tube ring clamps.

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View through finder scope

View through the SkyView Pro 120 EQ

Figure 5. Images through the finder scope will appear upside-

down and backwards (rotated 180°). Images through the SkyView
Pro 120 EQ with its diagonal in place will be reversed from left-to
right.

The telescope is now balanced on both axes. When you loos­en the lock lever on one or both axes and manually point the
telescope, it should move without resistance and should not
drift from where you point it.

5. Using Your Telescope

Focusing the Telescope

With the 25mm eyepiece inserted in the diagonal, 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 reversed
left-to-right. This is normal for astronomical telescopes
that utilize a star diagonal. The finder scope view will be
rotated 180° (see Figure 5).

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 metal thumbscrew on the top of the body of the focuser
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 SkyView Pro 120 EQ comes with a 8x40 achromatic find­er scope (Figure 3a). The number 8 means eight-times magni­fication and the 40 indicates a 40mm diameter front lens. The
finder scope makes it easier to locate the subject you want
to observe in the telescope, because the finder scope has a
much wider field-of-view.

The 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 tensioner moves
in and out to keep the finder scope secure in the bracket.

The finder scope must be aligned accurately with the tele­scope for proper use. To align it, first aim the main telescope
at an object at least a 1/4 mile away—the top of a telephone
pole, a chimney, etc. First, loosen the R.A. and Dec. lock
levers and move the telescope until it is pointing towards the
desired object; sight along the tube to aim the telescope. Turn
the focus knob until the object is properly focused. Make sure
to position the object in the center of the telescope’s eyepiece
by turning the R.A. and Dec. slow-motion control knobs. (The
R.A. and Dec. lock levers must be tightened to use the slow­motion control knobs).

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 thumbscrews 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. Make sure the object is still cen­tered in the telescope’s eyepiece. If it not still centered in the
eyepiece you must recenter it and repeat the alignment pro­cess.

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 objective lens
cell in or out of the finderscope body. Precise focusing will be

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