Collimation Of A Newtonian - Celestron XLT series Instruction Manual

Omni xlt series telescopes
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Perfect collimation will yield a star image very symmetrical just inside and outside of focus. In addition, perfect collimation
delivers the optimal optical performance specifications that your telescope is built to achieve.
If seeing (i.e., air steadiness) is turbulent, collimation is difficult to judge. Wait until a better night if it is turbulent or aim to a
steadier part of the sky. A steadier part of the sky is judged by steady versus twinkling stars.
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The
optical performance of most Newtonian reflecting telescopes can be optimized by re-collimating (aligni
telescope's optics, as needed. To collimate the telescope simply means to bring its optical elements into balan
Poo
r collimation will result in optical aberrations and distortions.
Before collimating your telescope, take time to familiarize yourself with all its components. The primary mi
th
e large mirror at the back end of the telescope tube. This mirror is adjusted by loosening and tightening th
sc
rews, placed 120 degrees apart, at the end of the telescope tube. The secondary mirror (the small, elliptical mirror
u
nder the focuser, in the front of the tube) also has three adjustment screws. To determine if your telescope needs
c
ollimation first point your telescope toward a bright wall or blue sky outside.
Never look directly at the sun with the naked eye or with a telescope (unless you have the proper solar filter).
Permanent and irreversible
Ali
gni g the Secondary Mirror
n
T
he
fol wing describes the procedure for daytime collimation of your telescope using the optional Newtonian
lo
Coll
ima on Tool (#94183) offered by Celestron. To collimate the telescope without the Collimation Tool, read the
ti
g section on night time star collimation. For very precise collimation, the optional Collimation Eyepiece
followin
1 ¼" (# 9
4182) is offered.
If y u h ve an eyepiece in the focuser, remove it. Rack the focuser tube in completely, using the focusing knobs,
o
a
until its s
ilver tube is no longer visible. You will be looking through the focuser at a reflection of the secondary
mirror, p
rojected from the primary mirror. During this step, i
m
irror. Insert the collimating cap into the focuser and look through it. With the focus pulled in all the way, you
shou b
ld e able to see the entire primary mirror reflected in the secondary mirror. If the primary mirror is not
c
entered
in the secondary mirror, adjust the secondary mirro
until the periphery of th
screw in the secondary mirror su
Aligning the Prim ry
Now adjust the primary mirror s
silhouetted against the ew of the primary. As you look into the focuser, silhouettes of the mirrors should
look concentric. Repeat ste
Remove the collimating cap and
the secondary mirror.
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eye damage may result.
e primar
y mirror is centered in your view. DO NOT loosen or tighten the center
pport, because it maintains proper mirror position.
a
M rror
i
crews to re-center the reflection of the small secon
vi
ps ne and two until you have achieved this.
o
look into the focuser, where you should see the reflection of your eye in
gnore the silhouetted reflection from the primary
r screws by alternately tightening and loosening them
42
ng) the
ce.
rror is
e three
dary mirror, so it's

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Omni xlt 102Omni xlt 120Omni xlt 150Omni xlt 127

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