Orion 7358 User manual

Orion®Quick-Collimation Cap
#7358
This Quick-Collimation Cap is a useful but inexpensive tool to aid in the pre-
cise collimation of telescope optics, most often those of Newtonian Reector
telescopes. The small hole in the center of the Quick-Collimation Cap ensures
that your eye is centered when looking into the focuser during the collimation
process to check the optical alignment.
Insert the collimation cap into the 1.25” collar of the telescope’s focuser, then
follow the instructions outlined below.
Collimation of Newtonian Reflector Optics
Collimation is the process of adjusting the optics of a telescope so they
are precisely aligned with one another and with the telescope tube. For a
Newtonian reector telescope, the primary and secondary mirrors must be
in precise alignment. Accurate mirror alignment is important to ensure the
sharpest possible images viewed through your telescope, so it should be
checked occasionally. With practice, collimating is relatively easy to do and
can be done in daylight.
It helps to perform the collimation procedure in a brightly lit room with the tele-
scope pointed toward a bright surface, such as a light-colored wall. The tele-
scope tube should be oriented horizontally (parallel to the ground). Placing a
piece of white paper in the telescope tube opposite the focuser (i.e., on the
other side of the secondary mirror from the focuser) will also be helpful (see
Figure 2). Check what tool(s), if any, will be needed to turn the collimation
screws for both the primary and secondary mirrors. For the secondary mirror
IN 679 10/22
INSTRUCTION MANUAL
Corporate Offices: 89 Hangar Way, Watsonville CA 95076 - USA
Toll Free USA & Canada: [phone]
International: [phone]
Customer Support: [email protected]
Copyright © 2022 Orion Telescopes & Binoculars. All Rights Reserved. No part of this
product instruction or any of its contents may be reproduced,copied, modied or
adapted, without the prior written consent of Orion Telescopes & Binoculars.
AN EMPLOYEE-OWNED COMPANY
Figure 1. The Orion Quick-Collimation Cap
collimation screws, you will typically need to use either a Phillips screwdriver
or an Allen wrench (and often a metric Allen wrench).
First you will want to check you telescope’s collimation to see if any adjust-
ment is even needed. Remove the eyepiece if one is installed in the focuser,
and look into the focuser.You should see the secondary mirror centered in the
focuser, as well as the reection of the primary mirror centered in the second-
ary mirror, and the reection of the secondary mirror (and your eye) centered
in the reection of the primary mirror, as in Figure 3A. Got all that? Review
it again carefully, and compare what you see to Figure 3A. If anything is off-
center, proceed with the following collimation procedure.
NOTE: Precise collimation is best achieved by using a collimating tool,
such as the Quick-Collimation Cap. Figures 3B through 3D assume that
you have the collimation cap installed in the focuser.
Primary Mirror Center Mark
You may have noticed that the primary mirror on your Newtonian reector tele-
scope has a small adhesive ring or dot in the center. This “center mark” allows
you to achieve a very precise collimation of the primary mirror; you don’t have
to guess where the center of the mirror is, which is important in the collimation
process. This center mark is especially useful when using a collimating tool
such as the Quick-Collimation Cap.
Note: The adhesive ring/dot should not 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! Leave it in place.
Aligning the Secondary Mirror
Align the secondary mirror rst, as follows.
With the collimation cap installed, look into the tiny hole in the center of the
cap. You will see the telescope’s secondary mirror. If the entire primary mirror
reection is not visible in the secondary mirror, as in Figure 3B, you will need
to adjust the tilt of the secondary mirror. This is done by alternately loosening
one of the three secondary mirror alignment screws then lightly tightening
Figure 2. Before collimating the telescope, place a piece of
white paper inside the tube opposite the focuser, and position
the optical tube in the horizontal position as shown.
Figure 3. Collimating the optics. (A) When the mirrors are properly aligned,
the view down the focuser drawtube should look like this. (B) Here, only part
of the primary mirror is visible in the secondary mirror, so the secondary
mirror needs to be adjusted (tilted). (C) Here the secondary mirror is correctly
aligned because the entire primary mirror is visible in it. But the reection
of the secondary mirror is off-center. So the primary mirror still needs
adjustment. (D) Now the primary mirror is correctly aligned, so the secondary
mirror is centered.
A.
B.
C.
D.

Figure 5. The optical tube’s rear cell has three pairs of collimation
screws. The larger knobs are the (often spring-loaded) collimation
knobs while the smaller thumbscrews are the locking screws.
Collimation
knob
Locking
thumbscrew
Out of collimation Collimated
Figure 6. A star test will determine if the telescope's optics are
properly collimated.
One-Year Limited Warranty
This Orion product is warranted against defects in materials or work-
manship for a period of one year from the date of purchase. This war-
ranty is for the benet of the original retail purchaser only. During this
warranty period Orion Telescopes & Binoculars will repair or replace,
at Orion’s option, any warranted instrument that proves to be defec-
tive, provided it is returned postage paid. Proof of purchase (such as
a copy of the original receipt) is required. This warranty is only valid
in the country of purchase.
This warranty does not apply if, in Orion’s judgment, the instrument
has been abused, mishandled, or modied, nor does it apply to nor-
mal wear and tear. This warranty gives you specic legal rights. It is
not intended to remove or restrict your other legal rights under appli-
cable local consumer law; your state or national statutory consumer
rights governing the sale of consumer goods remain fully applicable.
For further warranty information, please visit
www.OrionTelescopes.com/warranty.
Corporate Offices: 89 Hangar Way, Watsonville CA 95076 - USA
Toll Free USA & Canada: [phone]
International: [phone]
Customer Support: [email protected]
Copyright © 2022 Orion Telescopes & Binoculars.All Rights Reserved.
No part of this product instruction or any of its contents may be repro-
duced, copied, modied or adapted, without the prior written consent
of Orion Telescopes & Binoculars.
AN EMPLOYEE-OWNED COMPANY
Figure 4. Secondary mirror collimation is performed using the three
screws (usually Philips or Allen screws) circled here on the secondary
mirror holder.
Secondary mirror
collimation screws
the other two (Figure 4). The goal is to center the primary mirror reection in
the secondary mirror, as in Figure 3C. Don’t worry that the reection of the
secondary mirror is off-center.You will x that in the next step. It will take some
trial and error to determine which screws to loosen and tighten to move the
reection of the primary mirror to the center of the secondary mirror. But be
patient and you’ll get it.
Aligning the Primary Mirror
The nal adjustment is made to the primary mirror. It will need adjustment if,
as in Figure 3C, the reection of the primary mirror is centered in the second-
ary mirror, but the small reection of the secondary mirror is off-center. The
tilt of the primary mirror is adjusted using (usually) three spring-loaded col-
limation knobs and three smaller locking thumbscrews on the back end of the
optical tube (Figure 5).
First loosen the three locking thumbscrews a turn or so. Then tighten one of
the collimation knobs about a quarter turn and see if the secondary mirror
reection has moved closer to the center of the primary (where the center
ring/dot is). If it moved farther away then try loosening the same collimation
knob a bit. Repeat this process on the other two sets of collimation screws, if
necessary, adjusting them one way or the other and seeing if the secondary
mirror reection moves closer to the center of the primary mirror. It will take a
little trial and error to get a feel for how to tilt the mirror in this way. When the
center hole in your collimating tool is centered as much as possible in the ring/
dot on the primary mirror, your primary mirror is collimated. The view through
the collimation cap should resemble Figure 3D.
Finally, very lightly tighten the three locking thumbscrews so that the primary
mirror stays in that adjusted position.A simple star test will tell you whether the
optics are accurately collimated.
Star-Testing the Telescope
When it is dark, point the telescope at a bright star and accurately center
it in the eyepiece’s eld of view. Slowly de-focus the image with the focus-
ing knob. You should see a series of diffraction rings surrounding a dark cen-
ter spot, which is the shadow of the secondary mirror. If the diffraction rings
are perfectly circular around the dark spot, telescope is correctly collimated
(Figure 6). If the image is unsymmetrical, with rings that are not perfectly circu-
lar and the dark spot is not centered within them, the scope is out of collimation.
Note, however, that if the bright star you have selected is not 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 may need to make slight corrections to the telescope’s position in order to
account for the sky’s apparent motion.