ORION TELESCOPES & BINOCULARS 10269 User manual

Orion®6", 8", and 10" F/4
Newtonian Astrographs
#10269 - 6" f/4
#9505 - 8" f/4
#10271 - 10" f/4
IN 661 Rev. 06/21
INSTRUCTION MANUAL
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AN EMPLOYEE-OWNED COMPANY
#10269

2
Congratulations on your purchase of the Orion®
f/4 Newtonian Astrograph. These telescopes
feature fast, high-quality parabolic optics; a
machined, dual-speed Crayford focuser with
linear-track bearing; and excellent mechanical
construction. The 6", 8’, and 10" f/4 Newtonian
Astrographs have been specially optimized for
astrophotography with DSLR and astronomical
imaging cameras. This manual covers all three
astrographs. Other than their apertures, they are
similar; any signicant differences among them
will be noted. These instructions will help you set
up and use your telescope.
Figure 1. Components of the Orion F/4 Newtonian Astrographs
O-ring
Tube rings Finder scope
Collimation
cap
Battery holder
Tube assembly
Dovetail bar
Allen wrenches
Bolts
Dust
cover
Extension
adapter
Finder
scope
bracket
Table of Contents
Parts List 3
Getting Started 3
Operating the F/4 Newtonian Astrograph 6
Collimating the Optics 7
Care & Maintenance 11
Specications 12
WARNING: Never look directly at the Sun with
the naked eye or with a telescope – unless you have
a proper solar lter installed over the front of the
telescope! Otherwise, permanent, irreversible eye
damage may result.

3
Parts List
• Optical tube assembly
• Cooling fan (8" and 10" only, installed)
• Battery holder for cooling fan (8" and 10" only)
• Eyepiece adapter, 2" to 1.25" (installed in focuser)
• 8x50 nder scope
• Finder scope bracket and O-ring
• Tube rings (x2)
• Dovetail mounting bar
• M6 x 1.0 socket head cap screws (x2)
• Extension tube adapter, 35mm length
• Collimation cap
• Hex wrenches – 2.5mm and 5mm
• Dust cap
Getting Started
Your f/4 Newtonian Astrograph arrives nearly fully assembled
from the factory.The optics were collimated at the factory, how-
ever you should check the collimation prior to rst use (see
“Collimating the Optics”) as, not uncommonly after shipment,
an adjustment may be necessary.
We recommend that you keep all of the original packaging. In
the unlikely event you should need to ship the telescope back
to Orion for warranty repair service, you should use the original
packaging to ensure the telescope stays intact during shipping.
When unpacking the telescope, refer to the Parts List above
and Figure 1 to make sure everything is accounted for. Then
refer to Figure 2 to familiarize yourself with some of the fea-
tures and components of the telescope.
Connecting the Telescope to a Mount
The f/4 Newtonian Astrographs each come with a pair of
hinged, felt-lined tube rings to hold the optical tube assembly
(OTA). Each ring has a at riser on opposite sides. The taller
riser (on the bottom of the tube ring) bears a single M6 x 1.0
metric threaded hole. The other, atter riser (top of tube ring)
has a ¼"-20 threaded hole in the center.
Attach the dovetail bar to the bottom of the tube rings using the
included M6 x 1.0 socket head cap screws and the correspond-
ing 5mm Allen wrench (Figure 3). We recommend using the
through holes on the ends of the dovetail bar to put the bolts
through for tube ring attachment, although you could also use
one or both of the slots in the bar. For the 6" optical tube, the
tube rings should straddle the focuser, as shown in Figure 4A.
For the 8" and 10" f/4 astrographs, both tube rings should be
positioned between the focuser and the rear of the optical tube
for proper balance (Figure 4B). The included dovetail bar ts
mounts with a Vixen-style dovetail saddle.
The at risers on the top side of the tube rings can be used
to attach an optional dovetail bar for piggybacking another
telescope or a guide scope for astrophotoraphy. You will need
to purchase the appropriate length ¼"-20 bolts to attach an
optional dovetail bar to the rings.
Balancing the Optical Tube on a Mount
The optical tube must be balanced on both the right ascension
and declination axes of an equatorial mount for proper track-
ing and guiding. Balancing the F/4 Newtonian Astrographs
is achieved by sliding the dovetail mounting plate forward or
backward in the mount’s dovetail saddle. You can also move
the telescope forward or backward within the tube rings. To do
that, loosen the tube ring clamps slightly and slide the tele-
scope tube forward or backward as needed to reach optimum
balance, then retighten the tube ring clamps. Rotating the tele-
scope to achieve a comfortable eyepiece or camera angle is
done in the same fashion. Simply loosen the tube ring clamps
just enough to allow the optical tube to rotate within the tube
rings. Retighten the tube ring clamps securely once you have
reached the desired eyepiece or camera orientation
Dual-Speed Crayford Focuser with Linear Track
Bearing
The F/4 Newtonian Astrographs feature a machined aluminum,
dual-speed Crayford-type focuser (Figure 5) that incorporates
a linear track bearing design. The 6" and 8" f/4 have a 2" fo-
cuser and the 10" f/4 boasts a 3.3" focuser. The linear bearing
eliminates drawtube play and enables support of heavier loads
without slippage. If the drawtube does slip under the weight
of your imaging system or heavy visual accessories, simply
increase the drawtube tension by gently tightening the draw-
tube tensioning thumbscrew as needed.
The smooth focus motion and ne-focus wheel allow precision
adjustments for critical focusing of eyepieces and cameras.
Once you have reached focus, you can lock the drawtube in
place by tightening the focus lock thumbscrew.
The focuser drawtube has 50mm of travel and English and
metric hash marks, which allow you to note the drawtube posi-
tion at the precise focus point so you can return to it when you
need to.
Using 1.25" and 2" Accessories
The 2" focuser can accommodate both 1.25" and 2" acces-
sories, including just about any eyepiece or camera. Both the
2" holder and removable 1.25" adapter feature a brass com-
pression ring to hold your accessories in place without marring
their metal barrels.
The bottom of the 1.25" eyepiece adapter is threaded to accom-
modate 2" Orion lters. But with a lter installed, be careful
when inserting an eyepiece or Barlow lens into the adapter
for the rst time, to make sure the barrel is not long enough
to contact the lter – which could scar or crack it. If the eye-
piece or Barlow is too long, then it would be better to thread a
1.25" lter into the barrel of the eyepiece or Barlow itself, if it is
threaded to accept one
Fine Focus
The focuser features both coarse and ne focusing wheels.
The two large, silver-colored wheels are for coarse focusing.
The small black wheel next to the large focus wheel on the
right side allows ultra-precise focus adjustment at a gear ratio

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of 10:1, meaning ten turns of the ne focus wheel equals one
turn of the large focus wheel.
Use the large focus wheels to achieve rough focus on your
target object, then use the ne focus wheel to home in on the
exact focus point. You will be amazed at the amount of detail
that careful ne focus adjustment brings in to view on targets
such as the lunar surface, planets, double stars, as well as
other celestial objects.
Attaching the Finder Scope
The included 8x50 crosshair nder scope (Figure 6) is useful
for locating objects in the sky and centering them in the main
telescope’s eld of view.
To install it, rst remove the O-ring from the bracket and place
it over the body of the nder scope until it seats in the narrow
groove near the middle of the nder. Unthread the two black
nylon alignment screws on the bracket until the screw ends are
ush with the inside surface of the bracket. Slide the eyepiece
end (narrow end) of the nder scope into the end of the brack-
et’s cylinder opposite the alignment screws while pulling the
chrome, spring-loaded tensioning pin on the bracket with your
ngers (Figure 6A). Push the nder scope through the bracket
until the O-ring seats just inside the front opening. Release the
tensioner and tighten the two black nylon screws a couple of
turns each to secure the nder scope in place. The tips of the
tensioner and nylon screws should seat into the wide groove
on the nder scope’s body.
Now slide the foot of the nder scope bracket into the dovetail
base on the main telescope (Figure 6B). You’ll rst have to
back out the thumbscrew lock on the dovetail base a few turns
to allow the bracket to slide in. Once the bracket is inserted,
tighten the thumbscrew lock
Aligning the Finder Scope
The nder scope and the main telescope must be aligned so
they point to exactly the same spot in the sky. Alignment is
easiest to do in daylight. First, insert an eyepiece (a cross-
hair eyepiece is best) into the 35mm extension adapter and
insert the adapter into the telescope’s focuser. (If you’re using
a 1.25"-diameter eyepiece, you insert its barrel into the focus-
Figure 2. The dual-speed 2" Crayford-type linear bearing focuser
Accessory lock
thumbscrew
Focus lock thumbscrew
2" Collar
Accessory
lock
thumbscrew
10:1 Fine
focus wheel
Coarse
focus wheel
Drawtube tensioning
thumbscrew
Brass
compression ring
Accessory lock
thumbscrew
1.25" Adapter

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Lock ring
Spring pin
Figure 5. The aluminum 2" dual-speed linear bearing focuser.
Figure 3. Attach the tube rings to the dovetail bar using the
provided socket head cap screws and 5mm Allen wrench.
Figure 4.(A) For the 6" model we recommend that the tube rings
straddle the focuser as shown to allow proper balance. (B) For the
8" and 10" models both tube rings are positioned to the rear of the
focuser
Figure 6. (A) Insert the nder scope into the bracket. (B) Slide the
nder scope bracket into the dovetail base.
O-ring Thumbscrews
Compression
ring
Fine focus
wheel
2" collar
Coarse focus
wheels
1.25"
Adapter
Drawtube
tensioning
thumbscrew
Focus
lock
knob
B
A
A
Lock ring
O-ring
(not visible)
B

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er’s 1.25" adapter, then insert that into the 35mm extension
adapter.) You’ll need the 35mm extension adapter to reach
focus with most eyepieces. Point the telescope at an object
such as the top of a telephone pole or a street sign that is at
least a quarter-mile away. Move the telescope so the target
object appears in the very center of the eld of view when you
look into the eyepiece.
Now look through the nder scope. Is the object centered in
the nder scope’s eld of view? If not, hopefully it will be visible
some-where in the eld of view, so that only a minor adjust-
ment of the nder scope’s two alignment screws will be need-
ed to center it. Otherwise you’ll have to make coarser adjust-
ments to redirect the aim of the nder scope.
Once the target object is centered on the crosshairs of the
nder scope, look again in the telescope’s eyepiece and see
if it is still centered there as well. If it isn’t, repeat the entire
process, making sure not to move the telescope while adjust-
ing the alignment of the nder scope. When the target object
is centered on the crosshairs of the nder scope and in the
telescope’s eyepiece, the nder scope is aligned and ready to
be used for locating objects.
The nder scope alignment should be checked before every
imaging or observing session. This can easily be done at
night, before viewing through the telescope. Choose any bright
star or planet, center the object in the telescope eyepiece, and
then adjust the bracket's alignment screws until the star or
planet is also centered on the nder’s crosshairs.
Focusing the Finder Scope
If the image in the nder scope appears out of focus, you will
need to refocus the nder scope for your vision. First, loosen
the lock ring located behind the objective lens cell on the body
of the nder scope (See Figure 6B). Back the lock ring off by
a few turns. Then refocus the nder scope on a distant object
by rotating the objective lens cell clockwise or counterclock-
wise. Once the image appears sharp, retighten the lock ring
behind the objective lens cell. The nder scope’s focus should
not need to be adjusted again.
Operating the F/4
Newtonian Astrograph
Your F/4 Newtonian Astrograph is designed primarily for astro-
photography, but it makes a ne visual instrument as well.
For visual use, we recommend using high-quality eyepieces
to take full advantage of the instrument’s exceptional optical
quality. For imaging applications, the telescope is optimized
for use with an APS-C or smaller sensor, found in such cam-
eras as the Orion StarShoot G10 Deep Space Color imaging
Camera and StarShoot G26 APS-C Color Imaging Camera as
well as crop-sensor DSLRs and mirrorless cameras.
Cooling the Telescope
All optical instruments need time to reach “thermal equilibri-
um”. The bigger the instrument and the larger the temperature
change, the more time is needed. Allow at least 30 minutes
for your telescope to cool to the temperature outdoors. In very
cold climates (below freezing), it is essential to store the tele-
scope as cold as possible. If it has to adjust to more than a
40°F temperature change, allow at least one hour.You can use
the telescope while it’s cooling down, just note that you may
see “tube currents,” which interfere with the telescope’s ability
to resolve a sharp image. Tube currents are essentially heat
waves exiting both the optical components (such as the pri-
mary mirror) and the telescope itself. The effect seen through
the eyepiece is much like looking above a hot surface or re.
Mirror Cooling Fan
The 8" and 10" F/4 Newtonian Astrographs come with a cool-
ing fan installed on the rear of the primary mirror cell (Figure
7). Using the fan reduces the amount of time required for the
large primary mirror to reach thermal equilibrium with the
ambient air. The fan is powered by 12-volts DC. The included
battery holder holds eight AA alkaline batteries (not included).
Plug the cable from the battery holder into the fan’s power jack
located on the rear cell. Alternatively, the fan can be powered
by a 12-volt DC eld battery, such as the Orion Dynamo Pro.
You can run the fan prior to starting your imaging or observing
session, then turn it off, or keep it running during the session,
as there should be no noticeable vibration. However, it is prob-
ably not necessary to run the fan continuously for long periods
of time, unless the temperature is changing continuously and
rapidly.
Imaging with Your F/4 Newtonian Astrograph
The f/4 Newtonian Astrographs have fast F/4 parabolic optics,
which produce bright images and allow fairly short exposure
times. Fast optics also inherently produce some coma, or
distortion of star images toward the periphery of the eld of
view. Therefore, to achieve the best possible images, we rec-
ommend using a coma corrector (sold separately). The coma
corrector is attached to the focuser drawtube in front of the
camera body. Use of a coma corrector will allow you to utilize
the entire imaging area of your camera without the need to
crop the edges of your astro-images. Check Orion's website
for compatible coma correctors.
Attaching a CCD Camera
Most dedicated astronomical cameras have a 1.25" or 2" bar-
rel, or a nosepiece that allows attachment directly to your
telescope’s focuser like an eyepiece. No adapter is required.
Simply insert the nosepiece of the camera into the 1.25" or 2"
eyepiece holder and secure the camera with the thumbscrew
lock (Figure 8).
If your astro camera does not include a compatible nosepiece,
or if you wish to utilize the camera's T-threads, a zero-prole
prime focus camera adapter is required (available from Orion).
The zero-prole adapter has male T-threads that couple to the
female T-threads of your camera. The adapter's 2" barrel is
inserted and secured in the focuser just like a 2" eyepiece.
Attaching a DSLR Camera
To attach a DSLR camera, you will need the appropriate T-ring
for the make and model of your camera and a zero-prole
prime focus camera adapter (available from Orion). Simply
attach the T-ring to the camera body and thread the zero-pro-

7
le camera adapter onto the threads of the T-ring. Then insert
the barrel of the camera adapter into the focuser’s 2" eyepiece
holder (or an optional coma corrector) and secure it with the
two thumbscrew locks (Figure 9).
Visual Observing with the 8" F/4 Newtonian
Astrograph
To achieve focus with a telescope eyepiece, you will likely have
to use the included 35mm-long extension adapter (Figure 10).
Just insert it into the 2" collar on the focuser and tighten the
two thumbscrews to secure the extension adapter in place.
The insert either a 2" eyepiece or a 1.25" eyepiece (using the
1.25" adapter) into the 35mm extension adapter.
Collimating the Optics
(Aligning the Mirrors)
Collimating is the process of adjusting the mirrors so they are
aligned with one another. Your telescope’s optics were aligned
at the factory, and should not need much adjustment unless
the telescope was handled roughly in transit. Accurate mirror
alignment is important to ensure the peak performance of your
telescope, so it should be checked regularly. Collimating is a
relatively easy process and can be done in daylight or dark-
ness.
To check collimation, remove the eyepiece and look down the
focuser drawtube. You should see the secondary mirror cen-
tered in the drawtube, as well as the reection of the primary
mirror centered in the secondary mirror, and the reection of
the secondary mirror (and your eye) centered in the reection
of the primary mirror, as in Figure 11A. If anything is off-center,
proceed with the following collimating procedure.
The Collimation Cap
Your F/4 Newtonian Astrograph comes with a “quick collimation
cap” (Figure 12). This is a simple cap that ts on the focuser
draw-tube like a dust cap, but has a tiny hole in the center and
small black ring on the underside. The collimation cap helps
Figure 7. Rear of telescope
showing the installed cooling fan
and six collimation adjustment
knobs (three black collimation
knobs and three white lock
knobs).
Black collimation
knob (x3)
White lock
knob (x3)
Power jack
Nosepiece
Cooling fan
Back of
primary mirror
Figure 9. Attachment of a DSLR camera requires a T-ring for
the particular camera model and a T-adapter, such as the Orion
Zero-Prole Prime Focus Camera Adapter, which ts into the 2"
accessorycollar.
Figure 8. To use an astronomical CCD or CMOS camera with the
8" f/4.0 Newtonian Astrograph, the camera must have a 1.25" or 2"
nosepiece, which is inserted into the accessory collar in the focuser.
An external camera adapter with compatible threads could be used
in lieu of the nosepiece.
T-ring
Zero-prole
camera adapter
(not visible)

8
center your eye over the focuser drawtube so that aligning the
optical components is easier to achieve. The black ring pro-
vides a distinct visual reference that is helpful in centering the
primary and secondary mirror reections. Figures 11B through
11E assume that you have the collimation cap in place.
The Primary Mirror Center Mark
You’ll notice that the primary mirror of the F/4 Newtonian
Astrograph has a tiny ring (sticker) marking its center. This
“center mark” allows you to achieve a very precise collimation
of the primary mirror; you don’t have to guess where the exact
center of the mirror is.
NOTE: The center ring sticker need not ever be removed from
the primary mirror. Because it lies directly in the shadow of the
secondary mirror, its presence in no way adversely affects the
optical performance of the telescope or the image quality.That
might seem counterintuitive, but it’s true!
Preparing the Telescope for Collimating
Once you get the hang of collimating, you will be able to do it
quickly even in the dark. For now, it is best to collimate in day-
light, preferably in a brightly lit room and aimed at a white wall.
It is recommended that the telescope tube be oriented hori-
zontally. This will prevent any parts from the secondary mirror
from falling down onto the primary mirror and causing damage
if something comes loose while you are making adjustments.
Place a sheet of white paper inside the optical tube directly
opposite the focuser (Figure 13). The paper will provide a
bright “background” when viewing into the focuser.
Aligning the Secondary Mirror
To adjust the secondary mirror collimation, you will need both
a small and a large Phillips screwdriver.
You will need to check, and adjust if necessary, four aspects of
the secondary mirror’s alignment:
1. The secondary mirror’s axial position
2. The secondary mirror’s radial position
3. The secondary mirror’s rotational position
4. The secondary mirror’s tilt
The rst three will probably only need to be checked and (pos-
sibly) adjusted once. Thereafter, it is usually only the second-
ary mirror’s tilt that will need to be adjusted occasionally.
Adjusting the Secondary Mirror’s Axial Position
With the collimating cap in place, look through the hole in the
cap at the secondary (diagonal) mirror. Ignore the reections
Figure 10. The 35mm extension adapter adds 35mm of length to
the focuser drawtube. It is needed to reach focus for visual use of
the 8" F/4.0 Newtonian Astrograph.
Figure 11. Collimating the optics. (A) When the mirrors are properly aligned, the view down the focuser drawtube should look like this. (B)
With the collimation cap in place, if the optics are out of alignment, the view might look something like this. (C) Here, the secondary mirror is
centered under the focuser, but it needs to be adjusted (tilted) so that the entire primary mirror is visible. (D) The secondary mirror is correctly
aligned, but the primary mirror still needs adjustment. When the primary mirror is correctly aligned, the center “dot” of the collimation cap will
be centered, as in (E).
Primary mirror
center mark
Reflective surface
of collimation
cap
A.
B. C.
D. E.
Center
ring on
primary mirror

9
for the time being. The secondary mirror itself should be cen-
tered in the focuser drawtube. If it is off-center along the axis of
the telescope, i.e., positioned too far toward the front opening
or toward the rear of the telescope, as it is in Figure 11B, you
will have to adjust the mirror’s axial position.
To do so, use a small Phillips screwdriver to loosen the three
small alignment set screws in the center hub of the 4-vane
spider several turns. Now, grasp the mirror holder (the cylinder
that is attached to the back of the secondary mirror itself) with
one hand while turning the center screw with a large Phillips
head screwdriver with your other hand (Figure 14). Turning
the screw clockwise will move the secondary mirror toward the
front opening of the optical tube, while turning the screw coun-
ter-clockwise will move the secondary mirror toward the pri-
mary mirror. When the secondary mirror is centered axially in
the focuser drawtube, rotate the secondary mirror holder until
the reection of the primary mirror is as centered in the sec-
ondary mirror as possible. It may not be perfectly centered, but
Figure 12. The quick
collimation cap, which
features a black ring on
the underside, helps in
centering reections of
the optics in the focuser
during the collimation
process.
Figure 13. Placing a piece of white paper inside the optical tube
opposite the focuser provides a bright background when viewing
into the focuser.
Figure 16. On the 6" F/4, the larger, spring-loaded collimation
knobs are used to adjust the primary mirror tilt, while the thinner
knobs lock the mirror in place. Loosen each lock knob a couple turns
before adjusting the collimation knobs.
Lock knobs
Collimation knobs
Figure 14. To center the secondary mirror axially under the
focuser, hold the secondary mirror holder in place with your
ngers while adjusting the center screw with a large Phillips-head
screwdriver. Later you will adjust the tilt of the secondary mirror
by turning the three small set screws that surround the large
centerscrew.
Figure 15. To center the secondary mirror radially in the focuser
drawtube, make adjustments to the two knurled spider vane
thumbnuts that are perpendicular to the focuser.
Spider vane
thumb nuts

10
that is ne for now. Then, tighten the three small alignment set
screws equally to secure the secondary mirror in that position.
Adjusting the Secondary Mirror’s Radial Position
Like the axial position, the secondary mirror’s radial position
was set at the factory and will probably not need any adjusting,
or if it does, you’ll typically need to do it only once.
By “radial position” we mean the position of the secondary
mirror along the axis perpendicular to the focuser drawtube.
This position is changed by adjusting two of the spider vane
thumb nuts, as shown in Figure 15. Loosen one thumb nut,
then tighten the opposite one until the secondary mirror is cen-
tered radially in the drawtube. Do not loosen the thumb nuts
too much, to avoid having them completely unthread from the
ends of the spider vanes. Also, when making this adjustment,
be careful not to stress the spider vanes or they could bend.
Adjusting the Secondary Mirror’s Rotational
Position
The secondary mirror should face the focuser squarely. If the
mirror appears to be rotated away from the focuser, the mir-
ror’s rotational position will need to be adjusted. Again, this
adjustment will rarely, if ever, need to be done.
Grip the sides of the secondary mirror holder with your n-
gers. Then, using a large Phillips screwdriver, loosen the cen-
ter screw in the secondary mirror holder about a quarter of a
turn only (counterclockwise). That should be enough to free
up the secondary mirror to rotate slightly in either direction.
Look into the collimation cap and rotate the mirror slightly in
each direction to get an idea of how it affects the view of the
secondary mirror. Now rotate the mirror as needed so that it
precisely faces the focuser. Hold the mirror holder stationary
in that position while turning the center screw clockwise until
it is just tight (do not over-tighten). Sometimes the mirror may
rotate slightly when tightening the screw, so keep at it until the
mirror faces the focuser squarely and is secured in place.
Adjusting the Secondary Mirror’s Tilt
Finally, the tilt of the secondary mirror may occasionally require
adjustment. If the entire primary mirror reection is not visible
in the secondary mirror when using the collimation cap, as in
Figure 11C, you will need to adjust the tilt of the secondary
mirror. Using a small Phillips head screwdriver, rst loosen one
of the three alignment set screws by, say, one full turn, and
then tighten the other two to take up the slack. Do not loosen
the center screw during this process. The goal is to center the
primary mirror reection in the secondary mirror, as in Figure
11D. When it is centered, you’re done adjusting the secondary
mirror. Don’t worry that the reection of the secondary mirror
(the dark circle with the four spider vanes adjoining it) is off-
center, since that adjustment is made when aligning the pri-
mary mirror in the next step.
Aligning the Primary Mirror
The nal collimation adjustment is made to the primary mir-
ror. It will need adjustment if, as in Figure 11D, the second-
ary mirror is centered under the focuser and the reection of
the primary mirror is centered in the secondary mirror, but the
reection of the secondary mirror (dark circle containing the
light reective surface and center black “dot” of the collimation
cap) is off-center.
The tilt of the primary mirror is adjusted with three spring-load-
ed collimation bolts on the rear end of the optical tube (bot-
tom of the primary mirror cell). For the 8" and 10" f/4 models,
the spring-loaded collimation bolts are each tted with a black
knob (Figure 7). The alternating white knobs are attached to
lock bolts, which secure the mirror in place once the correct tilt
has been achieved. For the 6" f/4 model, the three large knobs
are the spring-loaded collimation knobs, while the thinner
knobs (thumbscrew heads) with the screwdriver slot in them
are the lock knobs (Figure 16).
To adjust the primary mirror’s tilt, rst loosen all three lock
knobs by turning them counterclockwise about one turn each.
Now, while looking into the focuser through the collimation
cap, turn one of the collimation knobs a half turn or so in either
direction and see if the secondary mirror reection moves
closer to the center of the primary. That is, does the “dot” of the
collimation cap appear to move closer to the ring on the center
of the primary mirror? If it does, great, keep going until you get
it as close as you can. If it doesn’t, try turning the collimation
knob in the opposite direction. If turning the one knob does not
seem to bring the dot closer to the ring, try using one of the
other collimation knobs. It will take some trial-and-error using
all three collimation knobs to properly align the primary mirror.
Over time you will get the feel for which collimation screws to
turn to move the image in a given direction.
When you have the dot centered as much as possible in the
ring, your primary mirror is collimated. Now lightly tighten the
three lock knobs to secure the primary mirror in that position.
The view through the collimation cap should now resemble
Figure 11E. A simple star test will indicate how well the tele-
scope optics are collimated.
Star-Testing the Telescope
When it is dark, point the telescope at a bright star and accu-
rately center it in the eyepiece’s eld of view. (To achieve focus
with an eyepiece, you will likely have to use the included
35mm extension adapter, as described previously.) Slowly de-
focus the image with the focusing knob. If the telescope is cor-
rectly collimated, the expanding disk should be a perfect circle
(Figure 17). If the image is unsymmetrical, the scope is out
of collimation. The dark shadow cast by the secondary mirror
Figure 17. A star test will determine if the telescope’s optics are
properly collimated. A defocused view of a bright star through the
eyepiece should appear as illustrated on the right if the optics are
perfectly collimated. If the circle is unsymmetrical, as illustrated on
the left, the optics need alignment.
Out of collimation Collimated

11
should appear in the very center of the out-of-focus circle, like
the hole in a donut. If the “hole” appears off-center, the tele-
scope is out of collimation.
If you try the star test and the bright star you have selected is
not accurately centered in the eyepiece, the optics will always
appear out of collimation, even though they may be perfectly
aligned. It is critical to keep the star centered, so over time you
will need to make slight corrections to the telescope’s position
in order to account for the sky’s apparent motion. Point the
telescope at Polaris (the north star) if you do not have a mount
that tracks.
Care & Maintenance
Give your telescope reasonable care and it will last a lifetime.
When not in use, keep its dust cover on as well as the dust cap
on the eyepiece opening. Keep the telescope inside the hard
storage carrying case when not in use. Store it indoors or in a
dry garage. Do not leave the telescope outside except when
using it. The optical tube is aluminum and has a smooth anod-
ized surface that should resist scratches and smudges. If a
scratch does appear on the tube, it will not harm the telescope.
Smudges on the tube can be wiped off with standard house-
hold cleaners such as Windex or Formula 409.
Cleaning Mirrors
In general, your telescope's mirrors will only need to be cleaned
very infrequently, if ever. Covering the front opening of the tele-
scope with the dust cover when it is not in use will prevent dust
from accumulating on the mirrors. Keeping the dust cap on the
focuser’s 1.25" opening is also a good idea. Improper cleaning
can scratch the mirror coatings, so the fewer times you have
to clean the mirrors, the better. Small specks of dust or ecks
of paint have virtually no effect on the visual or imaging perfor-
mance of the telescope.
The large primary mirror and the elliptical secondary mirror of
your telescope are front-surface aluminized and over-coated
with hard silicon dioxide, which prevents the aluminum from
oxidizing. These coatings normally last through many years of
use before requiring re-coating.
To clean the secondary mirror, rst remove it from the tele-
scope. Do this by keeping the secondary mirror holder station-
ary while completely unthreading the Phillips-head screw in
the center hub of the spider vane assembly. Do not touch the
mirror surface when doing this. Once the Phillips-head screw
is unthreaded, the secondary mirror and its holder can be
removed from the telescope. The secondary mirror does not
need to be removed from its holder for cleaning. Then follow
the same procedure described below for cleaning the primary
mirror.
To clean the primary mirror, rst carefully remove the mirror
cell from the telescope. To do so you must remove the six
screws on the exterior of the mirror cell (Figure 18). Then pull
the cell away from the tube.You will notice the primary mirror is
held in the mirror cell with three clips held by two screws each.
Loosen the screws and remove the clips.
You may now remove the primary mirror from its cell. Do not
touch the surface of the mirror with your ngers. Lift the mirror
carefully by the edges. Set the mirror on a clean soft towel. Fill
a clean sink or large bucket with room temperature water, a
few drops of liquid dishwashing detergent, and if possible, a
capful of 100% isopropyl alcohol. Submerge the mirror (alumi-
nized surface facing up) in the water and let it soak for a few
minutes (or hours if it’s a very dirty mirror). Wipe the mirror
under water with clean cotton balls, using extremely light pres-
sure and stroking in straight lines across the mirror surface.
Use one ball for each wipe across the mirror. Then rinse the
mirror under a stream of lukewarm water. Any particles on the
surface can be swabbed gently with a series of cotton balls,
each used just one time. Dry the mirror surface with a stream
of air (a “blower bulb” works great). Cover the mirror surface
with tissue, and leave the mirror in a warm area until it is com-
pletely dry before replacing it in the mirror cell. Then reinstall
the mirror cell in the telescope optical tube with the six screws.
Figure 18. To clean the primary mirror, you must remove the
mirror in its cell from the telescope tube. To do so, remove the six
Phillips-head screws that fasten the rear cell to the tube. Then
separate the cell from the tube.

12
Specifications
6" f/4 Newtonian Astrograph
Optical conguration: Newtonian reector
Aperture: 150mm (5.9")
Focal length: 610mm
Focal ratio: F/4.1
Primary mirror: BK-7 optical glass, parabolic gure, center marked
Mirror coatings: Enhanced aluminum (94% reectivity) with SiO2 overcoat
Secondary mirror minor axis: 62.5mm
Backfocus distance: 77.1mm (from 2" drawtube collar)
Focuser: Dual-speed (10:1) 2" linear bearing Crayford, with 1.25" adapter
Drawtube travel: 50mm
Optical tube: Rolled steel, gloss black enamel nish
Tube rings: Included, hinged, felt-lined
Finder Scope: 8x50, with dovetail bracket
Extension tube: 35mm length, 2" compression ring holder
Weight, assembled: 12.9 lbs. (5.85 kg)
Length: 22.8" (58.0cm)
8" f/4 Newtonian Astrograph
Optical conguration: Newtonian reector
Aperture: 200mm (7.9")
Focal length: 800mm
Focal ratio: F/4.0
Primary mirror: BK-7 optical glass, parabolic gure, center marked
Mirror coatings: Enhanced aluminum (94% reectivity) with SiO2 overcoat
Secondary mirror minor axis: 70mm
Back focus distance: 83.2mm (from 2" drawtube collar)
Focuser: Dual-speed (10:1) 2" linear bearing Crayford, with 1.25" adapter
Drawtube travel: 50mm
Optical tube: Rolled steel, gloss black exterior nish
Tube rings: Included, hinged, felt-lined
Finder Scope: 8x50, with dovetail bracket
Extension tube: 35mm length, 2" compression ring holder
Cooling Fan: Included, requires 8 AA batteries (not included)
Weight, assembled: 19.0 lbs., 15.7 oz. (9.06 kg)
Length: 27.9" (71.0cm)

13
10" f/4 Newtonian Astrograph
Optical conguration: Newtonian reector
Aperture: 250mm (9.8")
Focal length: 1000mm
Focal ratio: F/4.0
Primary mirror: BK-7 optical glass, parabolic gure, center marked
Mirror coatings: Enhanced aluminum (94% reectivity) with SiO2 overcoat
Secondary mirror minor axis: 88mm
Back focus distance: 92.4mm (from 2" drawtube collar)
Focuser: Dual-speed (10:1) 3.3" linear bearing Crayford, with 1.25" adapter
Drawtube travel: 50mm
Optical tube: Rolled steel, gloss black exterior nish
Tube rings: Included, hinged, felt-lined
Finder Scope: 8x50, with dovetail bracket
Extension tube: 35mm length, 2" compression ring holder
Cooling Fan: Included, requires 8 AA batteries (not included)
Weight: 33 lbs., 12.3 oz. (15.32 kg)
Length: 38.4" (97.5cm)

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od of one year from the date of purchase. This warranty is for the benet of the original
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This warranty does not apply if, in Orion’s judgment, the instrument has been abused,
mishandled, or modied, nor does it apply to normal wear and tear. This warranty gives
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under applicable local consumer law; your state or national statutory consumer rights
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