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8. collimation (aligning the Mirrors)
Collimation is the process of adjusting the alignment of the mirrors so that they
are perfectly aligned with each other. Accurate alignment is important to the peak
performance of your telescope and should be done on a regular basis. Your tele-
scope’s optics were aligned at the factory, but may have jiggled out of alignment
a bit during shipping or in normal handling. Collimation is easy to do and you
should become familiar with it to be sure that you are getting the maximum per-
formance from your scope.
secondary Mirror collimation
This is usually set at the factory and should be checked, but usually does not
need to be adjusted.
1. To aid in centering your eye while aligning the secondary mirror, use a collimat-
ing tool (Orion #3640). You can make one out of a black 35mm film canister. Cut
off a half inch from the top lip and put a 1/16" to 1/8" diameter hole in the cen-
ter of the bottom of the film canister. The film canister collimating tool goes into
the focuser like an eyepiece—with the bottom end out.
2. Look down the front of the tube to become familiar with the parts on the inside
of the telescope. Note the secondary mirror, the primary mirror and the reflec-
tions.
3. Put the film can into the focuser, end facing out. Turn the focuser all the way
down so that the focuser is as far in as it can be.
4. To check the secondary mirror alignment, look directly down the focuser
through the film can alignment tool at the secondary mirror. When it’s properly
aligned, the secondary mirror itself should be centered under the focuser, and
the entire reflection of the primary mirror should be seen. If either the secondary
mirror or the primary mirror reflection are not centered, the secondary mirror
will need to be adjusted.
5. Adjust the diagonal: In order to center the secondary mirror, loosen the large
allen head bolt on the back of the secondary mirror holder. By loosening or
tightening the bolt, the spring will push or pull the secondary mirror slightly
down the telescope tube. You can now also rotate the secondary holder into
proper position, if necessary. When done, tighten the three phillips head bolts
until they just touch the secondary holder.Now, to adjust the tilt of the second-
ary mirror in order to see the full reflection of the primary mirror, tighten or
loosen one of the phillips head screws relative to the others. If you tighten one,
you will need to loosen the other two, and vice versa.
aim the Primary Mirror
1. The primary mirror tilt is adjusted with the three phillips head bolts on the back
of the primary mirror cell. The three allen head bolts are a "lock" and should be
loosened before adjustments, and re-tightened after.
2. Again, look directly down the focuser. If the secondary mirror is properly adjust-
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View down the main telescope tube
Bottom end
of focuser tube
Edge of
secondary mirror
Reflection of
primary mirror
Primary mirror clip
Primary
mirror spot
Reflection of secondary
holder with four spider vanes
Secondary mirror holder
Reflection of
your eye
In Alignment
(Reflection is Centered)
Out of Alignment
(Reflection is Off Center)