Orion 9527 User manual

INSTRUCTION MANUAL
IN 378 Rev. A 1/10
Customer Support [phone] • E-mail: suppor[email protected]
Corporate Offices [phone] • 89 Hangar Way, Watsonville, CA 95076
Orion® 8" f/4.0
Newtonian Astrograph
#9527
Providing Exceptional Consumer Optical Products Since 1975
OrionTelescopes.com

2
Congratulations on your purchase of an Orion®8"
f/4.0 Newtonian Astrograph. It features fast, high-
quality parabolic optics; a machined, dual-speed
Crayford focuser with linear-track bearing; and
excellent mechanical construction. This telescope
has been specially optimized for astrophotography
with DSLR and astronomical CCD imaging cam-
eras. These instructions will help you set up and
use your telescope.
Parts List
Optical Tube Assembly
Optical tube dust cover
1.25" eyepiece adapter
8x50 finder scope with bracket
Pair of hinged tube rings
35mm extension tube adapter
Collimation cap
Battery holder for cooling fan
Getting Started
Your 8" f/4.0 Newtonian Astrograph arrives nearly fully
assembled from the factory. The optics were collimated at the
factory, however you should check the collimation prior to first
use to make sure it held during shipment (see “Collimating
the Optics”). Not uncommonly, a minor adjustment may be
necessary.
We recommend keeping 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 ship-
ping. Take a moment to inspect the telescope and all of its
parts.
Before proceeding with the instructions, refer to Figure 1 to
familiarize yourself with some of the features and components
of the telescope.
Connecting the Telescope to a Mount
The 8" f/4.0 Newtonian Astrograph comes with a pair of
hinged, felt-lined tube rings to hold the optical tube assembly.
Each ring has a flat boss on opposite sides. One boss has a
single M6 metric threaded hole. The other has three holes;
the center hole has a ¼"-20 thread and the two flanking holes
Figure 1. The 8" f/4.0 Newtonian Astrograph
8x50 Finder
scope
2" Accessory
collar
1.25" Adapter
Dovetail
finder scope
base
Focus lock
thumbscrew
Focuser
Primary mirror cell
Tube rings
Fine focus
wheel
Focus
wheel
Focus wheel
DETAIL
DETAIL
Drawtube
tensioning
thumbscrew
Secondary
mirror “spider”
Finder scope
bracket

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are M6. It is likely that only the center hole will be needed to
attach the rings to a dovetail plate for your mount or for your
guide scope assembly.
Balancing the 8" f/4.0 Newtonian Astrograph is achieved
by sliding the dovetail mounting plate (sold separately) for-
ward or backward within the mount’s dovetail saddle. You
can also move the telescope forward or backward within the
tube rings. The tube rings offer the most adjustment range.
Loosen the tube ring clamps slightly and slide the telescope
tube forward or backward as needed to reach optimum bal-
ance, 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 8" f/4.0 Newtonian Astrograph features a machined alu-
minum, 2" dual-speed Crayford-type focuser (Figure 2) that
incorporates a linear track bearing design. The linear bear-
ing 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
drawtube tensioning thumbscrew as needed.
The smooth focus motion and fine-focus wheel allow preci-
sion adjustments for critical focusing of eyepieces and camer-
as. 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
position at the precise focus point so you can return to it when
you need to.
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
Coarse
focus wheel
Drawtube tensioning
thumbscrew
Brass
compression ring
Accessory lock
thumbscrew
1.25" Adapter

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Using 1.25" and 2" Accessories
The 2" focuser can accommodate both 1.25" and 2" accesso-
ries, including just about any eyepiece or camera. Both the 2"
collar and removable 1.25" adapter feature a brass compres-
sion ring to hold your accessories in place without marring
their metal barrels.
The bottom of the 1.25" eyepiece adapter is threaded to
accommodate 2" Orion filters. But with a filter installed, be
careful when inserting an eyepiece or Barlow lens into the
adapter for the first time, to make sure the barrel is not long
enough to contact the filter – which could scar or crack it. If
the eyepiece or Barlow is too long, then it would be better to
thread a 1.25" filter into the barrel of the eyepiece or Barlow
itself, if it is threaded to accept one.
Fine Focus
The focuser features both coarse and fine focusing wheels.
The two large, silver-colored wheels are for coarse focus-
ing. The small black wheel next to the right-hand large focus
wheel allows ultra-precise focus adjustment at a gear ratio of
10:1, meaning ten turns of the fine 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 fine focus wheel to home in on the
exact focus point. You will be amazed at the amount of detail
that careful fine focus adjustment brings into 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 finder scope (Figure 3) is useful
for locating objects in the sky and centering them in the main
telescope’s field of view.
To install it, first remove the O-ring from the bracket and place
it over the body of the finder scope until it seats in the narrow
groove near the middle of the finder. Unthread the two black
nylon alignment screws on the bracket until the screw ends
are flush with the inside surface of the bracket. Slide the eye-
piece end (narrow end) of the finder scope into the end of the
bracket’s cylinder opposite the alignment screws while pull-
ing the chrome, spring-loaded tensioning pin on the bracket
with your fingers (Figure 4). Push the finder 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 finder scope in place.
The tips of the tensioner and nylon screws should seat into
the wide groove on the finder scope’s body.
Now slide the foot of the finder scope bracket into the dovetail
base on the main telescope. You’ll first 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 finder 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 crosshair
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-
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 field of view when you
look into the eyepiece.
Now look through the finder scope. Is the object centered
in the finder scope’s field of view? If not, hopefully it will be
visible somewhere in the field of view, so that only a minor
adjustment of the finder scope’s two alignment screws will be
needed to center it. Otherwise you’ll have to make coarser
adjustments to redirect the aim of the finder scope.
Once the target object is centered on the crosshairs of the
finder 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 finder scope. When the target object
Figure 4. Pull back the tensioner pin and slide the finder scope
into its bracket until the O-ring is seated in the bracket ring.
Figure 3. The 8x50 finder scope and bracket assembly.
Lock ring
O-ring
(not visible)
Tensioner
Black nylon
thumbscrews

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is centered on the crosshairs of the finder scope and in the
telescope’s eyepiece, the finder scope is aligned and ready to
be used for locating objects.
The finder 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 finder’s crosshairs.
Focusing the Finder Scope
If the image in the finder scope appears out of focus, you will
need to refocus the finder scope for your vision. First, loosen
the lock ring located behind the objective lens cell on the body
of the finder scope (Figure 3). Back the lock ring off by a few
turns. Then refocus the finder scope on a distant object by
rotating the objective lens cell clockwise or counterclockwise.
Once the image appears sharp, retighten the lock ring behind
the objective lens cell. The finder scope’s focus should not
need to be adjusted again.
Operating the 8" f/4.0
Newtonian Astrograph
Your 8" f/4.0 Newtonian Astrograph is designed primarily for
astro-imaging, but it makes a fine 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 size sensor, found in such cameras as
the Orion StarShoot™Pro, Orion Parsec™, and many DSLRs.
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 essential-
ly heat waves exiting both the optical components (such as
the primary mirror) and the telescope itself. The effect seen
through the eyepiece is much like looking above a hot surface
or fire.
Mirror Cooling Fan
The 8" f/4.0 Newtonian Astrograph comes with a cooling fan
installed on the rear of the primary mirror cell (Figure 5).
Using the fan reduces the amount of time required for the pri-
mary mirror to reach thermal equilibrium with the ambient air.
The fan is powered by 12-volts DC. The included battery hold-
er 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 field 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 ses-
sion, as there should be no noticeable vibration. However, it
is probably not necessary to run the fan continuously for long
periods of time, unless the temperature is changing continu-
ously and rapidly.
Figure 5. 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
Cooling fan
Back of
primary mirror

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Imaging with the 8" f/4.0 Newtonian Astrograph
This instrument has fast f/4.0 parabolic optics, which pro-
duce bright images and allow fairly short exposure times.
Fast optics also inherently produce some coma, or distor-
tion of star images toward the periphery of the field of view.
Therefore, to achieve the best possible images, we recom-
mend 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 CCD cameras have a 1.25" or 2" barrel, or nosepiece,
that allows attachment directly to your telescope’s focuser
like an eyepiece. No adapter is required. Simply insert the
nosepiece of the CCD camera (Figure 6) into the 1.25" or 2"
eyepiece holder and secure the camera with the thumbscrew
lock.
If your CCD imager does not include a compatible nose-
piece, or if you wish to utilize the camera’s T-threads, a Zero-
Profile Prime Focus Camera Adapter is required (available
from Orion). The zero-profile 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-Profile
Prime Focus Camera Adapter. Simply attach the T-ring to the
camera body and thread the Zero-Profile Camera Adapter
onto the threads of the T-ring. Then insert the barrel of the
camera adapter into the focuser’s 2" accessory collar and
secure it with the two thumbscrew locks (Figure 7).
Visual Observing with the 8" f/4.0
Newtonian Astrograph
To achieve focus with a telescope eyepiece, you will likely have
to use the included 35mm-long extension adapter (Figure 8).
Just insert it into the 2" collar on the focuser and tighten the
two thumbscrews to secure the extension adapter in place.
Then 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 mir-
ror alignment is important to ensure the peak performance of
your telescope, so it should be checked regularly. Collimating
Figure 6. To use a CCD camera with the 8" f/4.0 Newtonian
Astrograph, the camera must have a 1.25" or 2" nosepiece, which
is inserted into the appropriate accessory holder in the focuser.
An external camera adapter with T-threads could be used in lieu of
the nosepiece.
Figure 7. Attachment of a DSLR camera requires a T-ring for
the particular camera model and a T-adapter, such as the Orion
Zero-Profile Prime Focus Camera Adapter, which fits into the 2"
accessory collar.
Figure 8. 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.
1.25" nosepiece
T-ring
Zero-profile
camera adapter
(not visible)

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is a relatively easy process and can be done in daylight or
darkness.
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 reflection of the primary
mirror centered in the secondary mirror, and the reflection of
the secondary mirror (and your eye) centered in the reflection
of the primary mirror, as in Figure 9a. If anything is off-center,
proceed with the following collimating procedure.
The Collimation Cap
Your 8" f/4.0 Newtonian Astrograph comes with a “quick col-
limation cap” (Figure 10). This is a simple cap that fits on
the focuser drawtube like a dust cap, but has a tiny hole in
the center and a reflective inner surface. The collimation cap
helps center your eye over the focuser drawtube so that align-
ing the optical components is easier to achieve. The reflec-
tive surface provides a distinct visual reference that is help-
ful in centering the primary and secondary mirror reflections.
Figures 9b through 9e assume that you have the collimation
cap in place.
We strongly recommend the use of a laser collimating tool
such as the Orion LaserMate Deluxe or LaserMate Pro to
aid in collimating the optics. A laser collimator will ensure a
more precise collimation than you can usually achieve with
the included collimation cap. With fast optics like those of the
8" f/4.0 Newtonian Astrograph, getting a very precise colli-
mation is critical for obtaining the sharpest, crispest images,
so a laser collimator is a worthwhile (and small) investment.
However, for the purposes of this instruction, we’ll assume
that you don’t (yet) have a laser collimator, and that you’ll be
using the supplied collimation cap.
The Primary Mirror Center Mark
You’ll notice that the primary mirror of the 8" f/4.0 Newtonian
Astrograph has a tiny ring (sticker) marking its center. This
“center mark” allows you to achieve a very precise collimation
of the mirrors; you don’t have to guess where the exact center
of the mirror is.
Figure 9. 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).
Figure 10. The quick collimation cap, which features an inner
reflective surface, helps in centering reflections of the optics in the
focuser during the collimation process.
drawtube
Reflection
of primary
mirror clip
a.
b. c.
d. e.
Reflective surface of
collimation
cap
Center
ring on
primary mirror

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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 tele-
scope or the image quality. That might seem counter-
intuitive, 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
daylight, preferably in a brightly lit room and aimed at a light-
colored wall. It is recommended that the telescope tube be
oriented horizontally. 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 11). The
paper will provide a bright “background” when viewing into
the focuser. Just be sure to remove the paper when you’re
finished collimating.
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 first 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 reflections
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 open-
ing or toward the rear of the telescope, as it is in Figure 9b,
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 12). Turning
the screw clockwise will move the secondary mirror toward
the front opening of the optical tube, while turning the screw
counter-clockwise will move the secondary mirror toward the
primary mirror. When the secondary mirror is centered axially
in the focuser drawtube, rotate the secondary mirror holder
until the reflection of the primary mirror is as centered in the
secondary mirror as possible. It may not be perfectly cen-
tered, but that is fine 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 adjust-
ing, or if it does, you’ll typically need to do it only once.
Figure 11. Placing a piece of white paper inside the optical tube
opposite the focuser provides a bright background when viewing into
the focuser.
Figure 12. To center the secondary mirror axially under the
focuser, hold the secondary mirror holder in place with your
fingers 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.

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By “radial position” we mean the position of the secondary
mirror along the axis perpendicular to the focuser drawtube,
as shown in Figure 13. This position is changed by adjusting
two of the spider vane thumb nuts, as shown. Loosen one
thumb nut, then tighten the opposite one until the second-
ary mirror is centered 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 mak-
ing 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 fin-
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 reflection is
not visible in the secondary mirror when using the collima-
tion cap, as in Figure 9c, you will need to adjust the tilt of
the secondary mirror. Using a small Phillips head screwdriver,
first 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 reflection in the secondary mir-
ror, as in Figure 9d. When it is centered, you’re done adjust-
ing the secondary mirror. Don’t worry that the reflection 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 primary mirror in the next step.
Aligning the Primary Mirror
The final collimation adjustment is made to the primary mir-
ror. It will need adjustment if, as in Figure 9d, the secondary
mirror is centered under the focuser and the reflection of the
primary mirror is centered in the secondary mirror, but the
reflection of the secondary mirror (dark circle containing the
light reflective 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 (bottom
of the primary mirror cell). Each is fitted with a black hand
knob (Figure 5). The alternating white knobs are attached to
the lock bolts, which secure the mirror in place once the cor-
rect tilt has been achieved.
To adjust the primary mirror’s tilt, first loosen all three lock
bolts by turning the white knobs counterclockwise about one
turn each. Now, while looking into the focuser through the
collimation cap, turn one of the black collimation knobs a half
turn or so in either direction and see if the secondary mirror
reflection 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 black 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 white lock knobs to secure the primary mirror in place.
Figure 13. 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.
Figure 12. To center the secondary mirror axially under the
focuser, hold the secondary mirror holder in place with your
fingers 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.
Spider vane
thumb nuts

10
The view through the collimation cap should now resemble
Figure 9e. 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 field 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
correctly collimated, the expanding disk should be a perfect
circle (Figure 14). If the image is unsymmetrical, the scope
is out of collimation. The dark shadow cast by the second-
ary mirror 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 telescope 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 posi-
tion 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. Store the telescope indoors or
in a dry garage. Do not leave the telescope outside except
when using it. The optical tube has a smooth painted finish
that is fairly scratch-resistant. If a scratch does appear on the
tube, it will not harm the telescope. Smudges on the tube can
be wiped off with a soft cloth and household cleaning fluid.
Cleaning Mirrors
In general, your telescope’s mirrors will only need to be
cleaned very infrequently, if ever. Improper cleaning can
scratch the mirror coatings, so the fewer times you have to
clean the mirrors, the better. Small specks of dust or debris
have virtually no effect on the visual or imaging performance
of the telescope.
The primary mirror and secondary mirror of your telescope
are front-surface aluminized and over-coated with hard silicon
dioxide, which prevents the aluminum from oxidizing.
To clean the secondary mirror, first remove it from the tele-
scope. Do this by keeping the secondary mirror holder sta-
tionary while completely unthreading the Phillips-head screw
in the center hub of the spider vane assembly (see Figure
12). Do not touch the mirror surface when doing this. Once
Figure 15. 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.
Figure 14. 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