Collimation of a newtonian – Celestron XLT series User Manual
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C
C
The
ng) the
ce.
Poo
rror is
th
e three
rews, placed 120 degrees apart, at the end of the telescope tube. The secondary mirror (the small, elliptical mirror
nder the focuser, in the front of the tube) also has three adjustment screws. To determine if your telescope needs
ollimation first point your telescope toward a bright wall or blue sky outside.
eye damage may result.
Ali
n
he
lo
Coll
ti
followin
1 ¼” (# 9
o
a
until its s
mirror, p
gnore the silhouetted reflection from the primary
irror. Insert the collimating cap into the focuser and look through it. With the focus pulled in all the way, you
shou
b
entered
r screws by alternately tightening and loosening them
e primar
screw in the secondary mirror su
Aligning the Prim ry
i
Now adjust the primary mirror s
dary mirror, so it’s
silhouetted against the ew of the primary. As you look into the focuser, silhouettes of the mirrors should
look concentric. Repeat ste
o
Remove the collimating cap and
the secondary mirror.
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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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
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
e large mirror at the back end of the telescope tube. This mirror is adjusted by loosening and tightening th
sc
u
c
Never look directly at the sun with the naked eye or with a telescope (unless you have the proper solar filter).
Permanent and irreversible
gni g the Secondary Mirror
T
fol wing describes the procedure for daytime collimation of your telescope using the optional Newtonian
ima on Tool (#94183) offered by Celestron. To collimate the telescope without the Collimation Tool, read the
g section on night time star collimation. For very precise collimation, the optional Collimation Eyepiece
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,
ilver tube is no longer visible. You will be looking through the focuser at a reflection of the secondary
rojected from the primary mirror. During this step, i
m
ld e able to see the entire primary mirror reflected in the secondary mirror. If the primary mirror is not
in the secondary mirror, adjust the secondary mirro
c
y mirror is centered in your view. DO NOT loosen or tighten the center
pport, because it maintains proper mirror position.
until the periphery of th
a
M rror
crews to re-center the reflection of the small secon
vi
ps ne and two until you have achieved this.
look into the focuser, where you should see the reflection of your eye in