Celestron 94182 User manual

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41 "
Collimation Eyepiece- Model #94182
Collimation is the process of aligning the optical Using the Collimation Eyepiece
axes of all the optical elements in a telescope. When
properly collimated, all the mirrors (or lens) will be
1. Remove the eyepiece or any other accessory from
centered and angled so that the light entering the the focuser and rack the focuser all the way
in
telescope will form the sharpe pessible-irnag h towards the tube.
Collimation Eyepiece
is a
combination
of a "sight tube"
and a · "Cheshire eyepiece."
The sight tube portion
of the
Collimation eyepiece has
cross hairs to accurately define
the center
of the optical axis,
and
is used to make sure that
the secondary mirror is
centered directly under the
focuser. The Cheshire portion
of the eyepiece has a polished
45° angled element that
reflects light from the cutout
hole
in the side of the barrel
down into the optical path.
The polished flat element
projects a bright ring
of light,
providing a target for aligning
the primary mirror.
Identifying What You See.
Figure 2 represents what- a
properly collimated
Newtonian telescope would
look like when looking into the
focuser tube with the eyepiece
Sight Hole
Polished
45°
Reflective Flat
1%" Barrel
Crosshairs
Figure 1
2. Insert the Collimation
Eyepiece into the foeuser far
enough that the bottom edge
of the barrel appears slightly
larger than the outer edge
of
the secondary mirror when
looking through the sight
hole.
3. Rotate the eyepiece so
that the cutout on the side
of
the barrel is towards an
external light source.
(If
collimating at night, shine a
flashlight ' through the
cutout).
~ e ~ p J)i nt t ~
cutout side of the eyepiece
at or near the sun; serious
and instant eye damage
can result.
4. Look into the sight hole
to determine
if the
secondary
is positioned
directly under the focuser
tube.
-- The center of the
secondary mirror should be
positioned directly under the
intersection
of the cross
removed. The figure labels the major parts
of a hairs
of the Collimation Eyepiece, it will need to
typical Newtonian telescop
e. However, what you be ad
ju sted. This is usually done by rotating the
see when looking through your
t eles~01'e will threaded rod that holds the secondary holder.
depend on the manufacturer
of the telescope. For Additionally, the threaded rod can slide up and
example, many Celestron models use a single stalk down through the spider for adjustments
in the
to support the secondary mirror instead
of a four other axis. To adjust a stalk-type secondary
v~e spider. Therefore, when looking through the holder, there
is usually a center boit that can be
focuser you would see a single vane leading out to loosened to allow rotation
of the secondary holder.
the secondary mirror as opposed to four vanes.
5. Next, you need to adjust the tilt of the secondary
mi rror so that the entire reflection of the primary
mirror
is visible in the secondary mirror. Use the
hairs.
If the secondary is not centered in the cross
Celestron International, 2835 Columbia Street, Torrance, CA 90503· Phone [phone] • Fax [phone]

. Figure 2 - The view looking down the focuser of a collimated Newtonian reflector with
the eyepiece removed.
three· collimation screws located on the top of the
secondary mirror holder to center the reflection
of the
primary mirror underneath the cross hairs
of the
Collimation Eyepiece.
6.
Now that you can see the entire primary mirror
reflected
in the secondary mirror, you my notice that
the reflection'
of the secondary mirror is not perfectly
centered
in the primary mirror (see figure 4). To
correct this, you must adjust the primary mirror
collimation screws located on the bottom
of the
primary mirror celL
Tum the collimation screws,
one at a time,
reflected
in the
secondary
mirror
is
positioned in
the center of
the primary
mirror. For
added ease and
accuracy, a
small black dot
can be placed
in the center of
the primary
mirror and he
used to align
the primary..
Simply adjust
the mirror until
the dot on the
primary is
centered
in the
middle
of the
bright ring.
Crosshairs of
Collimation
until the center
of the bright ring
Secondary
Mirror (actual)
Spider vanes (or
stalk) reflected in
primary
Secondary Mirror
(reflected)
Mirror Dot (optional)
Prima
Secocdary
Holder
Primary Mirror Clips
If the view seen through the focuser tube resembles that of
figure 2, then your telescope is properly collimated and
ready for observing. However,
if the collimation is
noticeably off, repeat steps 5 and 6 until aligned.
Collimating a Schmidt-Cassegrain Telescope
Insert the Collimation Eyepiece directly into the visual back
of the telescope. The shadow of the secondary will appear
as a dark circle near the middle
of the field of view. Make
adjustments to the three collimation 3crews
in the center of
the corrector plate
to center the
secondary mirror on
the cross hairs.
This
is the only
collimation
adjustment possible
for this type
of
telescope, It should
~ke only a fragion
of a tum to make a
noticeable change
ill collimation,
Never loosen the
screw
in the center
of the secondary
housing;
it may
result in the mirror
coming o
ff its
mount.
Figure 3 - Make adjustments to the secondary mirror
until you can see the entire primary mirror reflected
in
the secondary mirror as in figure 4. :;;
I Figure 4 - Make adjustments to the primary mirror to
center the reflection of the secondary mirror inside
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Che primary mirror.
Warranty: One year limited warranty. See the Celestron Accessory Catalog (#93685) for complete warranty details or contact Celestron
#94182 (0100).
Celestron International, 2835 Columbia Street, Torrance, CA 90503· Phone (310) 328·9560 • Fax (310) 212·5835