SKY-WATCHER NEWTONIAN User manual

Collimation is the process of aligning the mirrors of your telescope
so that they work in concert with each other to deliver properly
focused light to your eyepiece. By observing out-of-focus star
images, you can test whether your telescope's optics are aligned.
Place a star in the centre of the field of view and move the focuser
so that the image is slightly out of focus. If the seeing conditions
are good, you will see a central of light (the Airy disc) surrounded
by a number of diffraction rings. If the rings are symmetrical about
the Airy disc, the telescope's optics are correctly collimated (Fig.a).
If you do not have a collimating tool, we suggest that you make a "collimating cap" out of a plastic 35mm
film canister (black with gray lid). Drill or punch a small pinhole in the exact center of the lid and cut off the
bottom of the canister. This device will keep your eye centered of the focuser tube. Insert the collimating cap
into the focuser in place of a regular eyepiece.
Collimation is a painless process and works like this:
Pull off the lens cap which covers the front of the telescope
and look down the optical tube. At the bottom you will see the
primary mirror held in place by three clips 120º apart, and at
the top the small oval secondary mirror held in a support and
tilted 45º toward the focuser outside the tube wall (Fig.b).
The secondary mirror is aligned by adjusting the central bolt
behind it, (which moves the mirror up and down the tube),
and the three smaller screws surrounding the bolt, (which
adjust the angle of the mirror). The primary mirror is adjusted
by the three adjusting screws at the back of your scope. The
three locking screws beside them serve to hold the mirror in
place after collimation (Fig.c. The screws on the back of your
telescope may be different.)
Aligning the Secondary Mirror
Point the telescope at a lit wall and insert the collimating cap into the focuser in place of a regular eyepiece.
Look into the focuser through your collimating cap. You may have to twist the focus knob a few turns until the
reflected image of the focuser is out of your view. Note: keep your eye against the back of the focus tube if
collimating without a collimating cap. Ignore the reflected image of the collimating cap or your eye for now,
instead look for the three clips holding the primary mirror in place. If you can't see them (Fig.d), it means that
you will have to adjust the three bolts on the top of the secondary mirror holder, with possibly an Allen wrench
or Phillip's screwdriver. You will have to alternately or loosen one and then compensate for the slack by tightening
the other two. Stop when you see all three mirror clips (Fig.e). Make sure that all three small alignment screws
are tightened to secure the secondary mirror in place.
Fig.b
Primary mirror
Support for
secondary mirror
Secondary mirror
Focuser
Fig.a
Corretly aligned Needs collimation
Fig.d
Primary mirror clip
Ignore the reflected
image for now
Fig.e
Primary mirror clip Primary mirror clip
Primary mirror clip
COLLIMATINGANEWTONIAN
Fig.c
Adjusting screw
Primary mirror
Mirror cell
Locking screw
1

2
Fig.f
Secondary
mirror
Primary mirror stop and keep your
hand here
Now run your hand around the front of your telescope keeping
your eye to the focuser, you will see the reflected image of
your hand. The idea here being to see which way the primary
mirror is defected, you do this by stopping at the point where
the reflected image of the secondary mirror is closest to the
primary mirrors' edge (Fig.f).
When you get to that point, stop and keep your hand there
while looking at the back end of your telescope, is there a
adjusting screw there? If there is you will want to loosen it
(turn the screw to the left) to bring the mirror away from that
point. If there isn't a adjusting screw there, then go across
to the other side and tighten the adjusting screw on the other
side. This will gradually bring the mirror into line until it looks
like Fig.g. (It helps to have a friend to help for primary mirror
collimation. Have your partner adjust the adjusting screws
according to your directions while you look in the focuser.)
After dark go out and point your telescope at
Polaris, the North Star. With an eyepiece in the
focuser, take the image out of focus. You will see
the same image only now, it will be illuminated
by starlight. If necessary, repeat the collimating
process only keep the star centered while
teaking the mirror.
Sky-Watcher Telescope
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Fig.g
Both mirrors aligned
with collimating cap in Both mirrors aligned with eye looking in focuser
Aligning the Primary Mirror
Find the three locking screws at the back of your telescope and loosen them by a few turns. Retighten the locking
screws when after the collimation.
hex bolt (Locking screw) Adjusting screw
If you see 3 hex bolts and 3 Phillip's
head screws, the hex bolts are the
locking screws and the Phillip's-head
screws are the adjusting screws. You
will need an Allen wrench to adjust
the locking screws.
If you see 3 large nuts protruding
from the back of your telescope
and 3 small Phillip's-head screws
besides them, the Phillip's-head
screws are the locking screws and
the large nuts are the adjusting screws.
Adjusting screw Locking screw
If you see 6 Phillip's-head screws
but 3 protruding from the back of
your telescope, the 3 protruding
screws are locking screws and the
ones next to them are adjusting
screws.
Adjusting screw
Locking screw