Bresser Optik AR-90, AR-102, AR-127S/L, AR-152S/L, NT-130 User guide

Operating Instructions

AR-90 · AR-102 · AR-127S/L · AR-152S/L· NT-130 · NT-150S/L · NT-203

General InformatIons / telescope features

d

G

H

f

e

I

J

1#

1$

C

B

1#

1)
1!

Fig. 1a: The Messier series telescope including a viewfinder. Optical Assembly (Newtonian model shown).

d

B

1^

f

e

H

C

I

AR = Achromatic Refractor -
NT = Newton - Reflectortelescope

g

1%

3(

3&

3*

3^

Fig. 1c: The Exos1 Tripod

3&

3%

3*

Technical Data Page 23!

3^

Fig. 1c: The Exos2 Tripod

2

1&
1*

1(



General InformatIons / telescope features

3#

3$

3)

3!

2!

2@

2#

1*

1(



2$

2&

1&

3$

3@

3!

2(
2*

2^

3)

2!

2#

2^

2&

2@

Explanations of the points See page 5 ff

WARNING!

Never use a Messier-Series Telescope to look at the Sun! Looking at or near the Sun will cause instant and irreversible
damage to your eye. Eye damage is often painless, so there is no warning to the observer that damage has occurred until
it is too late. Do not point the telescope or its viewfinder at or near the Sun. Do not look through the telescope or its view­finder as it is moving. Children should always have adult supervision while observing.

3

Looking at or near the Sun will cause instant and irreversible damage to your eye!

2(

2*

2^

Fig. 1d, top:
The Messier series mount
EXOS2
Fig. 1d, left:
The Messier series mount
EXOS1

Index

Chapter Page

Messier series: Your personal

window to the universe ........................................................ 5

Description of the features
Assembling (Exos 1)

Telescope Assembly ........................................................... 8

  How to Assemble Your Telescope   ..................................... 8

Assembling (Exos 2)

Telescope Assembly ......................................................... 11

  How to Assemble Your Telescope  .................................... 11

First Steps

   Balancing the Telescope  .................................................. 13

Aligning the Viewfinder ..................................................... 14

Choosing an Eyepiece ....................................................... 16

Observation ......................................................................... 17

Observing by Moving the Telescope Manually ................. 17

Observe the Moon ............................................................ 17

  Setting the Polar Home Position  ....................................... 18

Maintenance ........................................................................ 19

Maintenance guidelines ....................................................... 19

Alignment (Collimation)

of the Newtonian Optical System ..................................... 20

....................................................... 5

Chapter Page

Inspecting the Optics ........................................................... 21

Customer Service ................................................................ 22

Technical Data AR-102, AR-127 S/L und AR-152 S/L ......... 23

Technical Data NT-150 S/L, NT-203, AR-90 und NT-130 ... 22

Appendix A: Celestial coordinates ....................................... 25

Locating the Celestial Pole .................................................. 26

Setting Circles ..................................................................... 26

To use the setting circles to locate an object

not easily found by direct visual observation .................... 26

Appendix B: Latitude Chart  ................................................. 28

Appendix C: Polar Alignment .............................................. 30

Adjusting the polar viewfinder ............................................. 30

Polar alignment

by using the polar viewfinder Exos 2 only) ........................ 30

Appendix D: Basic astronomy  ............................................. 32

Appendix E: Star maps ....................................................... 37

IMPORTANT NOTE:

•   All Bresser telescopes and accessories are under constant technical advancement. Slight changes of the product specifications, 

which serve the improvement of the product, are reserved for this reason.

•   No part of this manual may be reproduced, sent, transferred or be translated into another language in any form without written 
 permission of the Bresser GmbH. Errors and technical changes excepted.

•  Please keep this guidance at hand for further looking up.

®  The name „Bresser“ and the Bresser Logo are registered trademarks. „Messier“ is a trademark of the Bresser GmbH
© 2014 Bresser GmbH, Germany

4

Which eyepiece is suitable for

B

which application? See p. 16

“choosing an eyepiece”

   How do I adjust the finder-

E

scope? See p. 14

   How do I mount the viewfin-

H

der? See p. 10, 9/9a

Want to learn more about

1!

mounting the telescope? See
p. 8-10 (Exos1) / p. 11-12
(Exos2)

telescope features

Messier series: Your personal
window to the universe

The Messier series models are versatile, high-resolution telescopes.
The Messier series models offer unmatched mechanical performance.
The Messier series telescopes reveal nature in an ever-expanding level of
detail. Observe the feather structure of an eagle from 150 yards or study
the rings of the planet Saturn from a distance of 800 million miles. Focus
beyond the Solar System and observe majestic nebulae, ancient star clusters,
and remote galaxies. Messier series telescopes are instruments fully capable of
growing with your interest and can meet the requirements of the most demand­ing advanced observer. Refer to Figures 1a through 1d for the following fea­tures:

Description of the features (Fig. 1a to 1d)

1 Eyepiece Thumbscrews: Tightens the eyepiece (see 3) in place.

Tighten to a firm feel only.

  2   Eyepiece Holder: Holds eyepiece in place. Holders supplied for both 

1.25“ and 2“ eyepieces (2“only for EXOS2 AR-models)           Diagonal

Prism (not shown, achromatic refractor models only): Provides a more
comfortable right-angle viewing position. Slide the diagonal prism
directly into the eyepiece holder (see 2) and tighten the thumbscrew
on the eyepiece holder to a firm feel only. See page 10 for a photo
and more information.

3 Eyepiece: Place the supplied eyepiece into the eyepiece holder or

the diagonal prism and tighten in place with the eyepiece thumbscrew
(see 2). The eyepiece magnifies the image collected in the optical
tube.

4 8 x 50mm Viewfinder: (6x30 only for smaller models) A low-power,

wide-field sighting scope with reticle that enables easy centering of
objects in the telescope eyepiece.

5 Viewfinder Collimation Screws: Use these screws to adjust the

alignment of the viewfinder.

6 Viewfinder Front Cell and Locking Ring: Adjust the front cell to focus

the viewfinder. See step 3, page 10 for more details. The viewfinder is
supplied with a small dust cover placed over the front cell.

  7  Viewfinder Bracket: Holds the viewfinder in place.

8 Focus Knobs: Moves the telescope’s focuser drawtube in a finely-

controlled motion to achieve precise image focus. The Messier series
telescopes can be focused on objects from a distance of about 500 ft.
to infinity. Rotate the focus knobs to focus on objects.

9 Dust Cover: Place the dust cover (not visible in photo) over the optical

tube when storing the telescope.

NOTE:

The dust cover should be replaced after each observing session. Allow
time for any dew that might have collected during the observing session
to evaporate prior to replacing the dust cover.

10 Optical Tube: The main optical component that gathers the light from

distant objects and brings this light to a focus for examination through

the eyepiece.
11 Cradle Assembly: Attaches to mount base. See 9.
13 Cradle Ring Lock Knobs (2 pcs.) and Washers
14 Cradle Rings: Part of the cradle assembly (see 11); hold the optical

tube firmly in place.
15   Viewfinder Bracket Screws: Tighten to a firm feel to hold viewfinder

securely in place (see 4). See page 10 for more information.
16 Focus Lock Knob: Designed to prevent the focuser drawtube from

moving when a heavy accessory, such as a camera, is attached to

Looking at or near the Sun will cause instant and irreversible damage to your eye!

5

Important:

1&

Before loosening the DEC lock, 

hold the optical tube in place;
otherwise it might swing through
and cause damage to the mount
or even hurt the operator.

telescope features

the focuser assembly. For normal observing with an eyepiece and diago­nal prism, it is not necessary to use the lock knob.

17 Dec. Lock: Controls the manual movement of the telescope. Turning the

Dec. lock counterclockwise unlocks the telescope enabling it to be freely

rotated by hand about the Dec. axis. Turning the Dec. lock clockwise (to

a firm feel only) tightens the lock and prevents the telescope from being

moved free, but engages the manual Dec. drive shaft.
18 Polar Viewfinder Cap (for EXOS2 models only): Remove this cap when

using the polar viewfinder (see 29).
19 Declination (Dec.) Setting Circle: See APPENDIX A, page 25, for more

information.
20   Counterweight Shaft Base: Thread, along with the shaft, to the mount.

See page 9 (Exos1) or 12 (Exos2) for more information.
21 Counterweight and Counterweight Lock Knob: Counterbalances the

weight of the optical tube, and adds stability to the mount. Tighten the

lock knob on the side of the counterweight to a firm feel to prevent the

weight from sliding on the shaft.
22 Counterweight Shaft: Slide the counterweight onto this shaft (see 21).
23 Counterweight Safety Cap: Prevents the counterweight from

accidentally slipping off the end of the counterweight shaft.
24 R.A. manual Drive Assembly:
26 Latitude Adjustment:

two handle screws work in a „push - pull“ operation—as you tighten one, 

loosen the other. The T-handle above the azimuth control knobs (see 27)

is the North T-handle screw (South in the Southern Hemisphere). This 

side of the mount must be pointed North (South in the Southern hemi

sphere) during the polar alignment procedure.

Sets the latitude of your observing location. The

-

Want to learn more about

2&

adjusting the latitude scale?
See p. 15, step 6.

Want to learn more about the

2(

polar finder? See p. 30.

DEFINITION:

In this manual, you will find the

terms “right aszension (RA), 

Declination (DEC), Elevation

and Azimut”. These terms are 

explained on p. 25

27 Fine Azimuth Control Knobs: Fine tune the side-to-side movement of

the telescope when centering Polaris in the telescope eyepiece or when

using the polar alignment viewfinder.
28 Latitude Dial: Set the latitude of the observing site on this dial using the

latitude T-handle screws. For more information see Step 6, page 9.
29 Polar Alignment Viewfinder (EXOS 2 only): Allows you to precisely polar

align the telescope.
30 Polar Alignment Viewfinder Reticle and LED Knob (EXOS 2 only):

Rotate the knob to switch on or off the LED that illuminates the reticle

within the polar alignment finder. Be sure to turn off the LED when 

finished with the polar viewfinder. Powered by (factory-supplied)

batteries contained within. Polar viewfinder LED illumination is available

seperately.
31 Right Ascension (R.A.) Setting Circle: See APPENDIX A, page 25.
32 R.A. Setting Circle Lock Knob: Rotate the knob to lock the R.A. Setting

Circle in place.
33 R.A. Lock: Controls the manual movement of the telescope. Turning the

R.A. lock counterclockwise unlocks the telescope enabling it to be freely

rotated by hand about the R.A. axis. Turning the R.A. lock clockwise (to

a firm feel only) tightens the lock and prevents the telescope from being

moved free, but engages the R.A. manual shaft.
34 DEC-manual drive assembly
35 Tripod Leg Adjustment Knobs: Tighten to a firm feel to secure tripod

legs.
36   Variable Height Tripod Legs: Supports the telescope mount. The mount

attaches to the top of the tripod.
37 Accessory tray: Set extra eyepieces and other accessory on this

convenient tray.
38

Tripod Leg Braces: Make the tripod more secure and stable. See Fig. 3.

6

Looking at or near the Sun will cause instant and irreversible damage to your eye!

telescope features

Messier Tips

Surf the Web
One of the most exciting resources for astronomy is the internet. The internet

is full of websites with new images, discoveries, and the latest astronomical

information.For example, when comet Hale-Bopp made its approach to our 

Sun in 1998,astronomers around the world posted new photos daily.
You can find websites for almost any topic relating to astronomy on the inter-

net. Try the following key word searches: NASA, Hubble, HST,  astronomy, 

Messier, satellite, nebula, black hole, variable stars, etc.

Check out Bresser’s website for the latest product and technical  information. 
You’ll find our website at: http://www.bresser.de/

Here are some other sites you might find interesting:

• Sky & Telescope:    http://www.Skyand Telescope.com

• Astronomy:    http://www.astronomy.com

• The Starfield:    http://users.nac.net/gburke/

• Astronomy Picture of the Day:    http://antwrp.gsfc.nasa.goc/apod

•   „Heaven´s Above“   www.heavens-above.com/

•  European Southern Observatory   www.eso.org

www.spacetelescope.org

Looking at or near the Sun will cause instant and irreversible damage to your eye!

7

Fig. 2a: The tripod

assemblInG exos1

Assembling (Exos1)

Telescope Assembly

As you unpack your telescope, carefully note the following parts. The
assembly is shipped in separate boxes.

• Equatorial mount with polar alignment finder

•  Heavy duty, adjustable steel tube tripod with leg braces, three tripod leg 

lock knobs, and a captive mount locking knob

•  Complete optical tube assembly including primary mirror with dust cover 
and a rack-and-pinion focuser and eyepiece holders for both 1.25“ and 2“

eyepiece holders, tube cradle assembly with two rings and two lock knobs

• Eyepiece

•  Counterweight and counterweight shaft. Some models include an 

additional counterweight.

• 8 x 50mm or 6 x 30mm viewfinder

How to Assemble Your Telescope

The giftboxes contain the optical tube assembly and the tripod with the
equatorial mount. The accessories are located within compartments custom­cut into the styrofoam block inserts.

instructions on telescope assembly. The packaging contains the main tube
and tripod components, the tripod with mounting and accessories.

Fig. 2b: tripod leg locks

Fig. 2c: Tripod head

1. Remove the components from the packaging and familiarise yourself

with them. Please refer to illustrations 1a to 1d for details of telescope
assembly. When removing the tripod from its packaging keep it parallel
to the floor as the inner legs may otherwise slide out as they are not yet
screwed tight.

2. Assembly - tripod: The tripod legs are preassembled and already con-

nected to the tripod head and accessory tray. Remove the tripod from
the packaging and place it in front of you, with the tripod legs on the

floor. Grab two legs and pull them apart until fully spread out. The tripod 

weight rests only on one leg. Now level the tripod and adjust third leg if
necessary. Pull out the bottom part of the leg to the desired length (Fig.
2b) and lock with the locking knob (3 pieces total) to a firm feel. Be care­ful not to over tighten the screws! These screws lock the inner leg seg­ments to the desired tripod height.

3. Assembly - mounting accessory tray: The accessory tray (Fig.: 2a) Is

placed on the tripod spider with the flat side facing down, then locked in
place turning the tray approximately 60° clockwise. The three gudgeons
of the tray should be centered on the spider vanes and lock in place.

Fig. 2d: central mount locking
screw

8

Looking at or near the Sun will cause instant and irreversible damage to your eye!

assemblInG exos1

5. Fastening the counterweight on the counterweight rod: insert the base
of the counterweight rod (20, illustration 1d) on the threaded end of the
rod and screw it on the counterweight rod (22, illustration 1). Then screw
both in the thread on the base of the declination axis and counter screw
rod to base. If you look through the large drill hole in the counterweight
you will see the bolt blocking the hole. Move the counterweight slightly

n

to make it disappear in its drill hole and reveal the hole. If it doesn‘t, 

carefully loosen the counterweight screw until the bolt moves. Remove

the safety cover (23, illustration 1d) from the rod. Hold the counterweight 

firmly whilst moving it to about the middle of the counterweight rod (22,
illustration 1d). Tighten the counterweight fastening screw and then
replace the safety cover.

Fig. 2e:
the Exos1 tripod.

installing the mounting on

Fig. 2f: Mounting the cradle (dovetail)
plate to the mount shaft (EXOS1)

A

Cradle

mounting

slot

Fig. 2g: Attach cradle to base mounting
and tighten locking (EXOS1)

B

NOTE:

If the counterweight ever slips, the safety cap (23, Fig. 1d) prevents the
counterweight from sliding entirely off the shaft. Always leave the safety cap
in place when the counterweight is on the shaft.

6. Set the latitude. Setting the latitude is easier if it is set before you attach

the optical tube to the assembly. Locate the latitude dial (28, Fig. 1d); note
that there is a triangular pointer above the dial located on the mount. The
pointer is not fixed; it moves as the mount moves.

Determine the latitude of your observing location. See APPENDIX B: 
 LATITUDE CHART, page 28-29, for a list of latitudes, or check an atlas.

Move the latitude T-handle screws in order to move the mount until the
pointer points to your latitude. The two T-handle screws (EXOS 2 only)

work in a „push - pull“ operation—as you tighten one, loosen the other. 

When the pointer points at your latitude, tighten both screws until they
make contact with the mount.
At your observing site, set up the telescope assembly so that this leg

approximately faces North (or South in the Southern Hemisphere). 

7. Attach the cradle assembly to the mount

optical tube from the cradle and slide the cradle assembly (11, Fig. 1a)
onto the cradle mounting slot. See Fig. 2g. The rounded base of the cradle
assembly fits into the rounded portion of the mounting slot. Tighten both the
cradle locking knob and the secondary locking knob to a firm feel.

8. Position optical tube –

knobs (13, Fig. 1a) and open the cradle rings. While firmly holding the
optical tube (10, Fig. 1a), position it onto the cradle rings (14, Fig. 1a)

with the mid-point of the optical tube’s length lying roughly in the center 

of the cradle ring assembly. Point the tube so that the front end (this
end comes shipped with the dust cover (9, Fig. 1a) over it) is oriented
as depicted in Fig. 1a. Then close the cradle rings (14, Fig. 1a) over the
optical tube. Loosely tighten the cradle ring lock knobs just to hold the

tube securely in place until you balance it. See Balancing the  telescope,  

page 13.

Models AR and NT:

–

Models R and N: Remove the

Unscrew the cradle ring lock

Fig. 2h: Place the optical tube
in rings and loosely tighten the
cradle ring lock knobs.

Looking at or near the Sun will cause instant and irreversible damage to your eye!

9

Fig. 9b: The finder scope assem­bly has a dovetail bracket, that
fits the holder that is mounted on
the optical tube.

Eyepiece

Holder

Thumbscrew

NT

Viewfinder

Fig. 10a: Insert eyepiece intor holder
and tighten thumbscrews.

Eyepiece

Thumbscrews

Diagonal
prism

Holder

AR

Viewfinder

assemblInG exos1

9.

Attach viewfinder bracket
(15, Fig. 1b and Fig. 9a) and remove the nuts from the screws. Slide
the holes in the viewfinder bracket over the viewfinder bracket screws.
Replace the nuts and tighten to a firm feel only.

9a. Attach viewfinder tube:. Back off the viewfinder collimation screws (5, 

Fig. 1b) and slide the viewfinder tube into the bracket. Orient the view­finder eyepiece as depicted in Fig. 1b. Tighten the collimation screws to
a firm feel. See Aligning the viewfinder, page 14.

10. Insert the eyepiece: NT models (Fig. 10a): Lift to remove the dust cap

from the eyepiece holder on the focuser assembly. Set the dust cap
aside in a safe place and replace it when you have finished observing

to protect the eyepiece assembly. Back off the eyepiece thumbscrews 

(1, Fig. 1a) and insert the supplied 25mm eyepiece (3, Fig. 1a) into the
the eyepiece holder. Tighten the holder thumbscrews to a firm feel to
secure the eyepiece. AR models (Abb. 10b): Lift to remove the dust cap
from the eyepiece holder on the focuser assembly. Set the dust cap
aside in a safe place and replace it when you have finished observing

to protect the  eyepiece assembly. Back off the eyepiece thumbscrews 

(1, Fig. 1b) and slide the diagonal prism into the holder and tighten the
thumbscrews to a firm feel only. Insert the supplied 25mm eyepiece (3,

Fig. 1b) into the the diagonal prism. Tighten the prism‘s thumbscrews to 

a firm feel to secure the eyepiece.

11. Adjust the height of the tripod: Adjust the height of the tripod by

loosening the tripod lock knobs (Fig. 11). Extend the sliding inner
section of each tripod leg to the desired length; then tighten each knob.
Adjust the tripod to a height that is comfortable for viewing.

13. Remove Plastic from Reticle LED

(30, Fig. 1d) contains two watch batteries. The reticle‘s LED is shipped 

with a plastic strip between the two batteries to protect battery life.
Unthread both the thumbscrew (F) and the threaded lid (E). Remove
the plastic strip before using. Refer to the reticle assembly in Fig. 13b
and note the orientation of the batteries. Place the batteries (C) into the
battery holder (D) before inserting into the reticle container (A).

(Abb. 9b). Locate the viewfinder bracket screws

*: The polar alignment reticle LED

Fig. 10b: Insert eyepiece into
diagonal prism and tighten
thumbscrews.

Leg lock knob

Fig. 11: Adjust the tripod height
using the leg lock knobs.

NOTE:

The 2” focusers of the Messier Series  from AR-102 or NT-130 on have a 

built in extension tube. Depending on the accessories used, or when using
a camera, it might not be possible to reach the focus. Focus travel to the
inside might not be sufficient in the standard configuration. To reach focus,
unscrew the eyepiece holder, then the following 25mm extension tube.
Screw the eyepiece holder back in place.

Looking at or near the Sun will cause instant and irreversible damage to your eye!

* Optional accessory for Exos 2

10

assemblInG exos2

Fig. 3: The tripod

F

E

E

C

B

A

Assembling (Exos2)

Telescope Assembly

As you unpack your telescope, carefully note the following parts. The assem­bly is shipped in separate boxes.

• Equatorial mount with polar alignment finder

•  Heavy duty, adjustable steel tube tripod with leg braces, three tripod leg 

lock knobs, and a captive mount locking knob

•  Complete optical tube assembly including primary mirror with dust cover 
and a rack-and-pinion focuser and eyepiece holders for both 1.25“ and 2“

eyepiece holders, tube cradle assembly with two rings and two lock knobs

• Eyepiece

•  Counterweight and counterweight shaft. Some models include an  additional 

counterweight.

• 8 x 50mm or 6 x 30mm viewfinder

How to Assemble Your Telescope

D

The giftboxes contain the optical tube assembly and the tripod with the equa­torial mount. The accessories are located within compartments custom-cut
into the styrofoam block inserts.

instructions on telescope assembly. The packaging contains the main tube
and tripod components, the tripod with mounting and accessories.

Fig. 4: Fastening the spacing plate
and distance washer in place.

A

B

Fig. 4a: Threaded rod fastening
using the C-clip

Gudgeon

Azimuth
fine adjust­ment

1. Remove the components from the packaging and familiarise yourself

with them. Please refer to illustrations 1a to 1d for details of telescope
assembly. When removing the tripod from its packaging keep it parallel
to the floor as the inner legs may otherwise slide out as they are not yet
screwed tight.

2. Locking the tripod legs. Spread the legs until the spider vanes of the

accessory plate are tautened (illustration. 3).

3. Fastening the spacing plate in place. To fasten the central screw (illustra-

tion 4, A) on the tripod first screw the tensioning screw (illustration 4, B) 

on. This can be screwed right down as it serves to clamp the spacing
plate against the tripod legs. You can now insert the plate (illustration 4,
C) from above on the central screw. Make sure the plate bars (illustra-

tion 4, D) show downwards. Caution. It‘s important the following step is 

applied to prevent thread damage. To prevent the threaded rod (illustra­tion 4, E) being screwed into the mount too far use the gapping washer
(illustration 4, F) supplied. Insert it from above on the threaded rod so
that the wider chamfered side shows downwards. The spacing ring must

be on the threaded rod „step“. Now push the threaded rod from below 

through the tripod base and slide the c-clip (illustration 4a, A) on the

recess (illustration 4a, B) in the threaded rod 

4b. Fastening the mount on the tripod top. Place the mounting on the tri-

pod top. Make sure the projection on the tripod is between the azimuth
adjustment screws (illustration 5). To do so first loosen the azimuth
screws sufficiently to allow space for the projection. Place the mounting
on the tripod top in such a way that the projecting cylinder on the base
fits into the hole in the tripod base centre and fasten it in place using the
central screw. Tighten the screw hand tight.

Fig. 5: installing the mounting on
the tripod.

11

Looking at or near the Sun will cause instant and irreversible damage to your eye!

5. Fastening the counterweight on the counterweight rod: insert the base of

the counterweight rod (20, illustration 1d) on the threaded end of the rod
and screw it on the counterweight rod (22, illustration 1). Then screw both
in the thread on the base of the declination axis and counter screw rod to
base. If you look through the large drill hole in the counterweight you will
see the bolt blocking the hole. Move the counterweight slightly to make

assemblInG exos2

DEC-setting circle

Shaft base

Lock knob

Shaft

Counter­weight

Safety cap

Fig. 6a: Attach counterweight
assembly (EXOS1)

Cradle

assembly set

A

Fig. 7: Mounting the cradle assembly
to the mount shaft (EXOS2)

Cradle rings

Lock
knobs

Fig. 8a: Place the optical tube
in rings and loosely tighten the
cradle ring lock knobs.

Fig. 9b: Viewfinder assembly.
Slide bracket into slot.

it disappear in its drill hole and reveal the hole. If it doesn‘t, carefully 

loosen the counterweight screw until the bolt moves. Remove the safety

cover (23, illustration 1d) from the rod. Hold the counterweight firmly 

whilst moving it to about the middle of the counterweight rod (22, illustra­tion 1d). Tighten the counterweight fastening screw and then replace the
safety cover.

NOTE:

If the counterweight ever slips, the safety cap (23, Fig. 1d) prevents the counter­weight from sliding entirely off the shaft. Always leave the safety cap in place when
the counterweight is on the shaft.

6. Set the latitude. Setting the latitude is easier if it is set before you attach the
optical tube to the assembly. Locate the latitude dial (28, Fig. 1d); note that
there is a triangular pointer above the dial located on the mount. The pointer
is not fixed; it moves as the mount moves.

Determine the latitude of your observing location. See APPENDIX B: 

B

 LATITUDE CHART, page 28-29, for a list of latitudes, or check an atlas. Move 

the latitude T-handle screws in order to move the mount until the pointer
points to your latitude. The two T-handle screws (EXOS 2 only) work in a

„push - pull“ operation—as you tighten one, loosen the other. When the point

-

er points at your latitude, tighten both screws until they make contact with the

C

mount. The EXOS 1 has on screw with similar operation.
At your observing site, set up the telescope assembly so that this leg approxi-

mately faces North (or South in the Southern Hemisphere). 

7. Attach the cradle assembly to the mount – Models R and N: Remove the opti

­cal tube from the cradle and slide the cradle assembly (11, Fig. 1a) onto the
cradle mounting slot. See Fig. 7. The rounded base of the cradle assembly fits
into the rounded portion of the mounting slot. Tighten both the cradle locking
knob and the secondary locking knob to a firm feel.

8. Position optical tube – Models AR and NT: Unscrew the cradle ring lock
knobs (13, Fig. 1a) and open the cradle rings. While firmly holding the optical
tube (10, Fig. 1a), position it onto the cradle rings (14, Fig. 1a) with the mid-

point of the optical tube’s length lying roughly in the center of the cradle ring 

assembly. Point the tube so that the front end (this end comes shipped with
the dust cover (9, Fig. 1a) over it) is oriented as depicted in Fig. 1a. Then
close the cradle rings (14, Fig. 1a) over the optical tube. Loosely tighten the
cradle ring lock knobs just to hold the tube securely in place until you bal

-

ance it. See Balancing the  telescope,  page 13.

9.

Attach viewfinder bracket

(Abb. 9b). Locate the viewfinder bracket screws
(15, Fig. 1b and Fig. 9a) and remove the nuts from the screws. Slide
the holes in the viewfinder bracket over the viewfinder bracket screws.
Replace the nuts and tighten to a firm feel only.

9a. Attach viewfinder tube:. Back off the viewfinder collimation screws (5, 

Fig. 1b) and slide the viewfinder tube into the bracket. Orient the view­finder eyepiece as depicted in Fig. 1b. Tighten the collimation screws to
a firm feel. See Aligning the viewfinder, page 14.

10. Insert the eyepiece: NT models (Fig. 10a): Lift to remove the dust cap
from the eyepiece holder on the focuser assembly. Set the dust cap
aside in a safe place and replace it when you have finished observing

to protect the eyepiece assembly. Back off the eyepiece thumbscrews 

(1, Fig. 1a) and insert the supplied 25mm eyepiece (3, Fig. 1a) into the
the eyepiece holder. Tighten the holder thumbscrews to a firm feel to
secure the eyepiece. AR models (Abb. 10b): Lift to remove the dust cap
from the eyepiece holder on the focuser assembly. Set the dust cap
aside in a safe place and replace it when you have finished observing

to protect the  eyepiece assembly. Back off the eyepiece thumbscrews 

(1, Fig. 1b) and slide the diagonal prism into the holder and tighten the
thumbscrews to a firm feel only. Insert the supplied 25mm eyepiece (3,

Fig. 1b) into the the diagonal prism. Tighten the prism‘s thumbscrews to 

a firm feel to secure the eyepiece.

Looking at or near the Sun will cause instant and irreversible damage to your eye!

12

fIrst steps

Eyepiece

Holder

Thumbscrew

Fig. 10a: Insert eyepiece intor holder
and tighten thumbscrews.

Eyepiece

Thumbscrews

Diagonal
prism

Holder

Fig. 10b: Insert eyepiece into
diagonal prism and tighten
thumbscrews.

Leg lock knob

NT

Viewfinder

AR

Viewfinder

NOTE:

Two eyepiece holders are included with your EXOS2-NT-telescope - for both 1.25” 
and 2” eyepieces. To change eyepiece holders, unscrew the attached holder from

the focuser and thread on the other holder.

11. Adjust the height of the tripod: Adjust the height of the tripod by
loosening the tripod lock knobs (Fig. 11). Extend the sliding inner
section of each tripod leg to the desired length; then tighten each knob.
Adjust the tripod to a height that is comfortable for viewing.

13. Remove Plastic from Reticle LED

(30, Fig. 1d) contains two watch batteries. The reticle‘s LED is shipped 

with a plastic strip between the two batteries to protect battery life.
Unthread both the thumbscrew (F) and the threaded lid (E). Remove
the plastic strip before using. Refer to the reticle assembly in Fig. 13b
and note the orientation of the batteries. Place the batteries (C) into the
battery holder (D) before inserting into the reticle container (A).

*: The polar alignment reticle LED

Getting Started! – First Steps

Balancing the Telescope

In order for the telescope to be stable on the tripod and also for it to move
smoothly, it must be balanced. To balance the telescope, unlock the Right
Ascension or R.A. lock (33, Fig. 1d). When this axis is unlocked, the tel­escope pivots on the R.A. axis. Later in the procedure, you will also unlock
the Declination or Dec. lock (17, Fig. 1d). When unlocked, the telescope
pivots on the Dec. axis. Most of the motion of the telescope takes place by
moving about these two axes, separately or simultaneously. Try to become
familiar with these locks and observe how the telescope moves on each
axis. To obtain a fine balance of the telescope, follow the method below:

Fig. 11: Adjust the tripod height
using the leg lock knobs.

1. Firmly hold the optical tube secure so that it cannot accidentally

swing freely. Loosen the R.A. lock (33, Fig. 1d). The optical tube now
moves freely about the R.A. axis. Rotate the telescope so that the
counterweight shaft is parallel (horizontal) to the ground.

2. Unlock the counterweight lock knob and slide the counterweight (21,

Fig. 1d) along the counterweight shaft until the telescope remains in one
position without tending to drift down in either direction. Then re-tighten
the counterweight lock knob, locking the counterweight in position.

3. Again, hold the optical tube so that it cannot accidentally swing freely.

Lock the R.A. lock (33, Fig. 1d), and unlock the Dec. lock (17, Fig. 1d).
The telescope now is able to move freely about the Dec. axis. Loosen
the cradle ring lock knobs (13, Fig. 1a) so that the main tube slides eas­ily back and forth in the cradle rings. Move the main tube in the cradle.

13

Looking at or near the Sun will cause instant and irreversible damage to your eye!

* Optional accessory for Exos 2



fIrst steps



Isolation pad



Typ 2x LR 44







*Fig. 13a: Reticle LED assembly:

(A) Reticle container

(B) LED
(C) Batteries
(D) Battery holder

(E) Threaded lid
(F) On/off switch

Aligning the Viewfinder

The wide field of view of the telescope‘s viewfinder (4, Fig. 1a) provides 
an easier way to initially sight objects than the main telescope‘s  eyepiece

(3, Fig. 1a), which has a much narrower field of view. If you have not
already attached the viewfinder to the telescope tube assembly, follow
the procedure described in step 9, page 9.

In order for the viewfinder to be useful, it must be aligned to the main

 telescope, so that both the viewfinder and telescope‘s optical tube (10, Fig. 

1a) point at the same position in the sky. This alignment makes it easier to
find objects: First locate an object in the wide-field viewfinder, then look into
the eyepiece of the main telescope for a detailed view.

To align the viewfinder, perform steps 1 through 4 during the daytime;

 perform step 5 at night. Both the 6 x 30mm and the 8 x 50mm viewfinders 

align in an identical manner. Refer to Fig. 14.

1. Remove the dust covers from the optical tube and the viewfinder.

2. If you have not already done so, insert the low-power 25mm eyepiece

(3, Fig. 1b) into the eyepiece holder of the main telescope.

See step 10, page 13.

3. Look through the viewfinder eyepiece at an object at least one-half mile

away (Tip: Remove the viewfinder tube from the bracket to simplify this
operation). If the distant object is not in focus, turn the focus lock ring
counterclockwise to loosen the viewfinder front cell (6, Fig. 1b). Twist the
front cell until focus is achieved and retighten the focus lock ring.

4. Unlock the R.A. lock (33, Fig. 1d) and the Dec lock (17, Fig. 1d) so

that the telescope turns freely on both axes. Then point the main tel­escope at a tall, welldefined and stationary land object (e.g., the top of
a telephone pole) at least 200 yards distant and center the object in the

telescope‘s eyepiece. Focus the image by turning the focus knobs (8, 

Fig. 1b). Retighten the R.A. and Dec. locks.

5. Look through the viewfinder and loosen or tighten, as appropriate, one

or more of the viewfinder collimation thumbscrews (5, Fig. 1b) until

the viewfinder’s crosshairs are precisely centered on the object you 
 previously centered in the main telescope‘s eyepiece. You are now ready

to make your first observations with your telescope.

3)

*Fig. 13b: Before using the illumi-

nation for the first time, remove the
isolation pad (See Fig. 13a) from
the battery holder.

Looking at or near the Sun will cause instant and irreversible damage to your eye!

* Optional accessory for Exos 2

14