Collimation of
Fixed‑Primary Mirror
Reflectors
Collimation
Collimation is the process of adjusting the telescope’s optical
elements so they are aligned with one another. Your reflector
telescope’s optics were aligned at the factory, and should not
need much adjustment unless the telescope was jarred while
in transit. Accurate mirror alignment is important to ensure
the peak performance of your telescope. And since the mir-
rors can go out of alignment occasionally, it should be checked
regularly.
Collimation is a relatively easy process and can be done in
daylight or darkness. To check collimation, remove the eye-
piece and look down the focuser drawtube. You should see
the secondary mirror centered in the drawtube, as well as the
reflection of the primary mirror centered in the secondary mir-
ror, and the reflection of the secondary mirror (and your eye)
centered in the reflection of the primary mirror, as in Figure 1a.
If anything is off-center, proceed with the following collimating
procedure.
The Collimation Cap
Your Orion reflector telescope comes with a “quick collimation
cap,” shown in
Figure 2. This is a simple cap that fits on the
focuser drawtube like a dust cap, but has a tiny hole in the
center and a reflective inner surface. The collimation cap helps
center your eye over the focuser drawtube, making it easier to
align the optical components. The reflective surface provides a
distinct visual reference that is helpful in centering the mirror
reflections
. Figures 1b and 1c assume that you have the col-
limation cap in place.
Primary Mirror Center Mark?
The primary mirror of your reflector telescope may or may not
have a tiny ring (sticker) marking its center. This “center mark” is
helpful in achieving a precise collimation, but it is not needed in
telescopes in which the primary mirror was aligned at the fac-
tory and fixed in place. If it is there, do not remove it as it does
not affect the view through the telescope in any way. If there is
no ring on the primary mirror, that’s OK as it is not needed.
Figure 1.
Collimating the optics.
(a)
When the mirrors are
properly aligned, the view down the focuser drawtube should
look like this;
(b)
With the collimation cap in place, if the
optics are out of alignment, the view might look something
like this;
(c)
After adjusting the secondary collimation
setscrews, the reflection of the primary mirror should be
centered in the secondary mirror as shown.
a.
b.
c.
Figure 2.
The
quick collimation
cap, which features
a reflective inner
surface, helps
in centering
reflections of
the optics in the
focuser during
the collimation
process.
IN 530 Rev. A 06/14
insTRuCTion Manual
WaRning:
Never look directly at the Sun with the
naked eye or with a telescope – unless you have
a proper solar filter installed over the front of the
telescope! Otherwise, permanent, irreversible eye
damage may result.
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