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Secondary
Front of
telescope
Secondary
reflection of
inside of tube
Figure 17a
Figure 17a.
If the telescope's optics are out of alignment
the view through the rear opening of the telescope will resemble
Figure‑2a.
collimating
To collimate your telescope, remove the diagonal and eyepiece
and look into rear opening of the tube (also remove the dust
cover from the front of the tube). This should be done indoors,
with the telescope pointed at a white wall in a well‑lit room. Try
to keep your eye centered with respect to the rear opening
of the tube as best as possible. Using an Orion Collimating
Eyepiece will aid greatly in keeping your eye centered and is
strongly recommend.
Alternatively, you can make a crude collimating tool out of an
empty, black plastic 35mm film canister. It will not have cross‑
hairs, so it won't be as precise, but it will be better than noth‑
ing. Cut 1/2" from the top lip of the canister and put a 1/16" to
1/8" diameter hole in the center of its bottom. Insert the film
canister collimating tool into the focuser like an eyepiece with
the bottom end out.
Once you are ready to collimate, look into rear opening of the
tube. If your telescope is out of collimation, it will resemble
Figure 17a. A properly collimated scope will resemble Figure
17b. The direction of the misalignment in your telescope may
differ from Figure 17a, but the diagram will give you the gen‑
eral idea of how things will look.
Note there are six alignment screws on the back of the opti‑
cal tube, three large and three small. You will need 4mm and
2.5mm Allen wrenches to turn these screws. These alignment
screws push and pull the mirror cell in order to tilt it. When you
loosen or tighten one of these screws, the other five screws
must be adjusted as well to keep the proper amount of pres‑
sure on the back of the mirror cell. By making slight adjustments
to how much the screws are tightened and loosened, you will
change the alignment of the primary mirror.
mirror
Reflection of
your eye in
secondary
mirror
Reflection of
inside of tube
(misalignment)
Secondary
Front of
telescope
Figure 17b
Figure 17b.
With the optics properly aligned the view through
the rear opening of the telescope will resemble Figure 2b.
Look into the rear opening of the tube and locate the black
crescent that shows the telescope is out of alignment. (Figure
17a). Note which way the front of the telescope would need to
move in order to "fill" that black crescent and resemble Figure
17b. Then look at the back end of the telescope and locate
the alignment screw that is in the direction that the front of
the telescope needs to move. For example, if the view in your
telescope resembled Figure 17a, then you would want to move
the front opening of the telescope scope to the right. The align‑
ment screw you would start with would be the screw on the
right as shown in Figure 18.
Your actions now depend on whether this alignment screw is
a small or large screw. Please note that you will be working to
adjust the mirror cell by keeping all the screws not too loose
and not too tight. Follow the steps listed below carefully and
refer to the figures that accompany them.
Figure 3
mirror
Reflection of
your eye in
secondary
mirror
Figure 18.
If the view through
the rear opening of the telescope
resembled Figure 17a, then the
alignment screw you would start
with would be this one. The actual
first alignment screw you would
pick will vary depending on which
way the front opening would need
to move in order to "fill" the black
crescent.
17
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