Orion 9786 Users Manual

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INSTRUCTION MANUAL

IN 319 Rev. A 09/07

Providing Exceptional Consumer Optical Products Since 1975

Customer Support (800)-676-1343

E-mail: support@telescope.com

Corporate Offices (831)-763-7000

89 Hangar Way, Watsonville, CA 95076

Orion® 6" Newtonian

Imaging Reflector

#9786

2

Figure 1. The 6" Newtonian Imaging Reflector.

Focuser

Focus

wheel

Primary mirror cell

Secondary

mirror holder

Fine focus

wheel

Dovetail holder

Focuser

thumbscrew

Drawtube

extension

thumbscrew

Focus

wheel

Focus lock

thumbscrew

3

Congratulations on your purchase of an Orion 6"

Newtonian Imaging Reflector.

Your 6" Newtonian Imaging Reflector is a Newtonian reflec-

tor telescope with high quality optics and excellent mechani-

cal construction. It has been specially optimized for use with

astronomical CCD imaging cameras. These instructions will

help you set up and use your telescope.

Getting Started

The 6" Newtonian Imaging Reflector comes nearly fully

assembled from the factory. The telescope’s optics have been

installed and collimated, so you should not have to make any

adjustments to them.

Please keep the original shipping box! In the unlikely event

you should need to ship the telescope back to Orion for war-

ranty repair service, you should use the original packaging.

The box also makes a very good container for storing the tele-

scope when it is not in use.

Attaching the 6" Newtonian Imaging Reflector to

a Mount

The 6" Newtonian Imaging Reflector can be attached to a

mount by the use of optional tube rings. Tube rings with an

inner diameter of 182mm (7.16"), such as Orion item #7375,

are needed. First attach the tube rings to your telescope

mount, then place the optical tube in the tube rings.

Use of Optional Finder Scope and Eyepieces

The 6" Newtonian Imaging Reflector OTA does not come with

a finder scope or eyepieces in order to grant the user the great-

est versatility in customizing the instrument to suit their tastes.

However, certain rules for using accessories still apply.

To connect a finder scope, simply unthread the thumbscrew

on the dovetail holder (Figure 1), and insert the base of the

finder scope bracket. Retighten the thumbscrew to secure the

finder scope and bracket in place. Finder scopes that do not

use a dovetail bracket will need to be attached by some other

means.

Almost any 1.25" or 2" eyepiece can be used with the 6" New-

tonian Imaging Reflector.

To use 2" eyepieces, you will need to remove the 1.25" eye-

piece adapter by loosening the drawtube thumbscrew by a

few turns and lifting the adapter out of the focuser. Place your

2" eyepiece in the focuser drawtube and secure it in place

with the thumbscrew.

In order to use a 1.25" eyepiece in the focuser, the 1.25" eye-

piece adapter is needed. Place this adapter into the drawtube

like a 2" eyepiece, and loosely secure it with the thumbscrew.

Insert a 1.25" eyepiece into the adapter, and secure the eye-

piece by further tightening the thumbscrew. Tightening the

thumbscrew compresses the 1.25" eyepiece adapter, which

in turn secures and precisely centers the 1.25" eyepiece.

The Dual-Speed Low-Profile Crayford Focuser

The 6" Newtonian Imaging Reflector comes equipped with a

high-quality dual-speed low-profile Crayford focuser. Crayford

focusers generally perform better than rack-and-pinion mod-

els because the design eliminates “focus shift.” Focus shift

occurs when an image changes position in the eyepiece dur-

ing focusing. The Crayford design provides constant tension

via four “roller bearings” and the focus shaft, so the drawtube

cannot move perpendicular to the desired motion.

The Crayford focuser provides a minimum focus height of

43mm, which is excellent for imaging applications that require

extra in-travel. The focuser also features a built-in extendable

drawtube which adds up to 44mm of travel yielding a total

focus range of 68mm. Extension of this drawtube is required

to achieve focus in an eyepiece with the telescope. To extend

the drawtube, loosen the drawtube extension thumbscrew

(Figure 1) and gently pull the drawtube upwards to the pre-

ferred position. Tighten the drawtube extension thumbscrew

to lock the extension in place. The extendable drawtube is a

welcome feature when switching between an eyepiece and

imager, as no external extension tubes are required.

Dual-Speed Focus Adjustments

The focuser features dual speed adjustment with the fine

focus wheel. This small black knob located on the side of the

right-hand focus wheel allows precise focus adjustment at a

ratio of 11:1, meaning eleven turns of the fine focus wheel

equals one turn of the focus wheel.

Use the focus wheels to achieve rough focus on your target

object, then use the fine focus knob to coax out even more

detail. You’ll be amazed at the amount of detail the fine focus

knob allows you to view on targets such as the lunar surface,

planets, double stars, as well as other celestial objects.

If you find that the focus wheels are too tight or too loose, you

can make adjustments to the drawtube tension by using the

drawtube tension adjustment set screw located on the bottom

of the focuser, between the focus wheels. Make adjustments

to this set screw with the provided 2.5mm hex key until the

focuser motion feels comfortable. Please note that you must

have at least some tension applied to the focuser drawtube or

else it will not move when you turn the focus wheels.

Once you have achieved focus, you can lock the focuser in

place by tightening the focus lock thumbscrew located between

on the bottom of the focuser between the focus wheels (Figure

1). Locking the focuser in place can be especially useful for

imaging applications. Be sure to loosen the focus lock thumb-

screw before making additional focus adjustments.

The focuser can be rotated, should the need arise. This

requires a 1.5mm hex key (not included). To reposition the

focuser, loosen the 4 small socket-head set-screws that are

located within the base. Rotate the focuser to the preferred

position and carefully tighten the four set screws with the

1.5mm hex key. Be sure to keep the focuser flat against the

base to ensure proper alignment.

Calculating Magnification (Power)

It is desirable to have a range of eyepieces of different focal

lengths to allow viewing over a range of magnifications. To

calculate the magnification, or power, of a telescope, simply

4

divide the focal length of the telescope by the focal length of

the eyepiece:

Telescope Focal Length (mm)

= Magnification

Eyepiece Focal Length (mm)

For example, the 6" Newtonian Imaging Reflector, which has

a focal length of 750mm, used in combination with a 25mm

eyepiece, yields a magnification of

750 mm

= 30x

25 mm

Every telescope has a useful limit of power of about 45x-60x

per inch of aperture. Claims of higher power by some tele-

scope manufacturers are a misleading advertising gimmick

and should be dismissed. Keep in mind that at higher pow-

ers, an image will always be dimmer and less sharp (this is

a fundamental law of optics). The steadiness of the air (the

“seeing”) will usually limit how much magnification an image

can tolerate.

Always start viewing with your lowest-power (longest focal

length) eyepiece in the telescope. After you have located and

observed the object with it, you can try switching to a higher-

power eyepiece to ferret out more detail, if atmospheric con-

ditions permit. If the image you see is not crisp and steady,

reduce the magnification by switching to a longer-focal-length

eyepiece. As a general rule, a small but well-resolved image

will show more detail and provide a more enjoyable view than

a dim and fuzzy, over-magnified image.

Astroimaging with the 6" Newtonian

Imaging Reflector

The 6" Newtonian Imaging Reflector has been specifically

designed for use with astronomical CCD imaging cameras

like the Orion StarShoot, but other imaging systems such as

digital SLR cameras will also work well with the telescope.

The secondary mirror of the 6" Newtonian Imaging Reflector

has been sized appropriately to provide a fully illuminated

field of view for Orion StarShoot cameras and most popular

digital SLR models.

Unlike most Newtonian reflector designs, the 6" Imaging

Reflector's secondary mirror has been recessed further into

the tube to prevent off-axis glare from being detected by imag-

ing devices. Glare can contaminate night-sky images by reduc-

ing image contrast and giving the object a “soft” appearance.

To use your CCD camera with the 6" Newtonian Imaging

Reflector, the camera must have a 1.25 inch “nosepiece”.

Otherwise an external camera adapter with T-threads is

required. All Orion StarShoot cameras feature this nosepiece

(Figure 2). Insert the nosepiece equipped camera into the

focuser just like an 1.25" eyepiece.

If your camera does not include a 1.25" nosepiece, you have

a digital SLR, or if you wish to utilize a secure T-thread con-

nection with a CCD camera like the Orion StarShoot, a zero-

profile camera adapter is required (available from Orion). The

zero-profile adapter is inserted into the focuser just like a 2"

eyepiece and provides T-threads for attachment of digital SLR

T-rings or T-threaded CCD cameras.

To attach a digital SLR to the telescope, remove any attached

lenses and connect a model-specific T-ring to the camera

body. Thread the T-ring onto the zero-profile adapter to com-

plete attachment. To securely attach a CCD imaging cam-

era like the Orion StarShoot via T-threads, remove the 1.25"

nosepiece and thread the CCD camera onto the zero-profile

camera adapter to complete attachment.

Due to its imaging-optimized design, no external extension

tubes are required to appropriately couple the telescope to an

imaging camera.

To record an image of a night-sky object, you will need to first

acquire and center the object with an eyepiece. You may need

to extend the focuser’s built-in extension tube to achieve focus

with an eyepiece. Once you have centered the target object

in the eyepiece field of view, remove the eyepiece and insert

your CCD camera into the telescope’s focuser (don’t forget

to retract the built-in extension tube if it has been extended).

Secure the camera with the thumbscrew on the focuser. Use

the focus and fine-focus wheels to bring the image into focus.

Collimating the Optics

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 is handled roughly. Accurate mirror alignment is

important to ensure peak performance of your telescope, so it

should be checked regularly. Collimating is relatively easy to

do and can be done in daylight.

To check optical alignment, remove the eyepiece and look

down the focuser drawtube. You should see the secondary

mirror centered 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 3a. If anything

is off-center, proceed with the following collimating procedure.

The Collimating Cap and Primary Mirror Center Mark

Your 6" Newtonian Imaging Reflector comes with a collimat-

ing cap. This is a simple cap that fits on the focuser drawtube

like a dust cap, but has a hole in the center and a silver bot-

Figure 2. To use a CCD camera with the 6" Imaging OTA, the

camera must have a 1.25” nosepiece, like the Orion StarShoot

Imaging cameras, or else an external camera adapter with

T-threads is required.

1.25" nosepiece

5

tom. This helps center your eye so collimating is easy to per-

form. Figures 3b through 3e assume you have the collimating

cap in place.

In addition to the collimating cap, you’ll notice a small ring

label on the exact center of the primary mirror. This “center

mark” allows you to achieve a very precise alignment of the

primary mirror; you don’t have to guess where the center of

the mirror is. You simply adjust the primary mirror position

(described below) until the reflection of the hole in the col-

limating cap is centered inside the ring.

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 counter-intuitive, but it’s true!

Aligning the Secondary Mirror

It helps to adjust the secondary mirror in a brightly lit room with

the telescope pointed toward a bright surface, such as white

paper or wall. Placing a piece of white paper in the telescope

tube opposite the focuser (i.e. behind the secondary mirror)

will also be helpful in collimating the secondary mirror.

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 isn’t, as in Figure 3b, it must

be adjusted. Typically, this adjustment will rarely, if ever, need

to be done.

Note: When make adjustments to the secondary mirror position,

be careful not to stress the spider vanes, or they may bend.

To adjust the secondary mirror left-to-right in the focuser

drawtube, use the included 2.5mm hex key to loosen the three

small alignment setscrews in the center hub of the 4-vaned

spider several turns. Now hold the mirror holder stationary

(be careful not to touch the surface of the mirror), while turn-

ing the center screw with a Phillips head screwdriver (Figure

4). Turning the screw clockwise will move the secondary mir-

ror 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 cen-

tered left-to-right in the focuser drawtube, rotate the second-

Figure 3. 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 “dot” will be centered, as in (e).

drawtube

Reflection

of primary

mirror clip

a.

Primary mirror

center mark

Reflective surface

of collimation

cap

b. c.

d. e.

Figure 4. To center the secondary mirror under the focuser, hold

the secondary mirror holder in place with your fingers while adjusting

the center screw with the Phillips head screwdriver. Do not touch the

mirror’s surface.

Phillips head

screwdriver

6

ary mirror holder until the reflection of the primary mirror is as

centered in the secondary mirror as possible. It may not be

perfectly centered, but that is OK for now. Tighten the three

small alignment setscrews equally to secure the secondary

mirror in that position.

To adjust the secondary mirror up-and-down in the focuser

drawtube, adjust the length of the two spider vanes perpen-

dicular to the focuser. This is done by tightening the knurled

thumbnuts that secure the vanes to the tube (Figure 5).

Loosen one thumbnut, then tighten the other until the second-

ary mirror is centered in the drawtube.

The secondary mirror should now be centered in the focuser

drawtube. Now we will shift our attention to the reflections

within the secondary mirror.

If the entire primary mirror reflection is not visible in the sec-

ondary mirror, as in Figure 3c, you will need to adjust the tilt

of the secondary mirror. This is done by alternately loosen-

ing one of the three alignment setscrews while tightening the

other two, as depicted in Figure 6. You will need a 2mm hex

key to do this. The goal is to center the primary mirror reflec-

tion in the secondary mirror, as in Figure 3d. Don’t worry that

the reflection of the secondary mirror within the primary mirror

reflection (the smallest circle, with the collimation cap “dot” in

the center) is off-center. You will fix that in the next step.

Once the secondary mirror is centered in the focuser draw-

tube, and the primary mirror reflection is centered in the sec-

ondary mirror, the secondary mirror is properly aligned, and

no further adjustments to it should be needed.

Aligning the Primary Mirror

The final adjustment is made to the primary mirror. It will need

adjustment if, as in Figure 3d, the secondary mirror is cen-

tered in the focuser drawtube and the reflection of the pri-

mary mirror is centered in the secondary mirror, but the small

reflection of the secondary mirror (with the “dot” of the col-

limating cap) is off-center.

The tilt of the primary mirror is adjusted with the three large

knurled thumbscrews on the rear end of the optical tube (back

of the mirror cell) (Figure 7). The small thumbscrews (with

slots in them) serve to lock the mirror in place. Start by loos-

ening each of these smaller thumbscrews a few turns. Use a

screwdriver in the slots, if necessary. Now adjust the tilt of the

primary mirror by turning one of the large thumbscrews either

clockwise or counterclockwise. Look into the focuser and see

if the secondary mirror reflection has moved closer to the

center of the primary mirror reflection. You can determine this

easily with the collimating cap and primary mirror center mark

by simply watching to see if the “dot” of the collimating cap is

moving closer or farther away from the “ring” on the primary

mirror. If it isn’t getting closer, try turning the thumbscrew in

the opposite direction. Repeat this process for the other two

large thumbscrews, if necessary. It will take a little trial-and-

error to get the feel for how to adjust the primary mirror to

center the dot of the collimating cap in the ring of the primary

mirror center mark.

When you have the dot centered as much as possible in the

ring, your primary mirror is aligned. The view through the colli-

mating cap should resemble Figure 3e. Make sure the smaller

thumbscrews on the back of the mirror cell are tightened to

lock the primary mirror in position.

Figure 7. The tilt of the primary mirror is adjusted by turning the

three larger thumbscrews.

Figure 5. To center the secondary mirror up-and-down in the

focuser drawtube, make adjustments to the two knurled spider vane

thumbnuts that are perpendicular to the focuser.

Spider vane

thumbnuts

Figure 6. Adjust the tilt of the secondary mirror by loosening one

of the three alignment set screws then tightening the other two.

Alignment set

screws (3)

7

Figure 8. 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 optics are per-

fectly collimated. If the circle is unsymmetrical, as illustrated on the

left, the scope needs alignment.

Out of collimation Collimated

A simple star test will tell you whether the optics are, in fact,

accurately aligned.

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. Slowly de-focus

the image with the focus knob. If the telescope’s optics are

correctly aligned, the expanding disk should be a perfect cir-

cle (Figure 8). If the image is unsymmetrical, the optics are

out of alignment. The dark shadow cast by the secondary mir-

ror 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

optics are out of alignment.

If you try the star test and the bright star you have selected

is not accurately centered in the eyepiece, the telescope will

appear to need optical alignment, even though the optics may

be perfectly collimated. 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.

Care & Maintenance

If you give your telescope reasonable care, it will last a life-

time. Store it in a clean, dry, dust-free place, safe from rapid

changes in temperature and humidity. Do not store the tele-

scope outdoors, although storage in a garage or shed is OK.

Small components like eyepieces and other accessories

should be kept in a protective box or storage case. Keep the

dust cover on the front of the telescope and the dust cap on

the focuser drawtube when it is not in use.

Your telescope requires very little mechanical maintenance.

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. If you wish, you may apply some auto

touch-up paint to the scratch. Smudges on the tube can be

wiped off with a soft cloth and household cleaning fluid.

Cleaning Mirrors

You should not have to clean the telescope’s mirrors very

often; normally once every year or so is fine. Covering the

front opening of the telescope 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 flecks of paint have virtually no effect

on the visual performance 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, 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 4).

Do not touch the mirror surface when doing this. Be careful,

there is a spring between the secondary mirror holder and

the Phillips head screw; be sure it does not fall into the opti-

cal tube and onto the primary mirror. Once the Phillips-head

screw is unthreaded, the secondary mirror and its holder can

be removed from the telescope. Then follow the same pro-

cedure described below for cleaning the primary mirror. The

secondary mirror does not need to be removed from its holder

for cleaning.

To clean the primary mirror, first carefully remove the mirror

cell from the telescope. For the 6" Imaging Reflector, you must

completely unthread the four screws on the exterior perimeter

of the mirror cell (Figure 9). 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 fingers. Lift the mirror

carefully by the edges. Set the mirror on a clean soft towel. Fill

a clean sink free with room temperature water, a few drops

of liquid dishwashing detergent, and if possible, a capfull of

Figure 9. To remove the mirror cell from the telescope, the four

small Phillips-head screws on the perimeter of the mirror cell must

be completely unthreaded.

Small Phillips-head screws (4)

8

One-Year Limited Warranty

This Orion 6" Newtonian Imaging Reflector is warranted against defects in materials or workmanship for

a period of one year from the date of purchase. This warranty is for the benefit of the original retail pur-

chaser only. During this warranty period Orion Telescopes & Binoculars will repair or replace, at Orion’s

option, any warranted instrument that proves to be defective, provided it is returned postage paid to:

Orion Warranty Repair, 89 Hangar Way, Watsonville, CA 95076. If the product is not registered, proof of

purchase (such as a copy of the original invoice) is required.

This warranty does not apply if, in Orion’s judgment, the instrument has been abused, mishandled, or

modified, nor does it apply to normal wear and tear. This warranty gives you specific legal rights, and

you may also have other rights, which vary from state to state. For further warranty service information,

contact: Customer Service Department, Orion Telescopes & Binoculars, 89 Hangar Way, Watsonville, CA

95076; (800)-676-1343.

Orion Telescopes & Binoculars

89 Hangar Way, Watsonville, CA 95076

Customer Support Help Line (800)‑676‑1343 • Day or Evening

100% isopropyl alcohol. Submerge the mirror (aluminized

face 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 pressure and strok-

ing 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 tis-

sue, and leave the mirror in a warm area until it is completely

dry before replacing it in the mirror cell and telescope.

Specifications

Optical tube: Steel

Primary mirror: Parabolic, center marked

Collimation adjustment: Three spring-loaded thumbnuts

to adjust mirror tilt, one thumbnut

in-line with focuser, three thumb-

screws to lock mirror position

Aperture: 6" (150mm)

Focal length: 750mm

Focal ratio: f/5.0

Minor axis of

secondary mirror: 2.28" (58.0mm)

Secondary mirror offset: 2.9mm away from focuser and

2.9mm towards primary mirror

Mirror coatings: Aluminum with silicon dioxide

(SiO2) overcoat

Focuser: Crayford, accepts 2" accessories,

dual-speed focus adjustment,

rotatable, focus-lock equipped

Minimum focus height: 43mm

Focus travel: 24mm, 68mm with 2" drawtube

extended

1.25" adapter: Included, compression-fit design

Weight: 10.5 lbs.

Length: 30.5"