Reflector or "Newtonian" type telescopes use a primary and secondary mirror to direct light to the telescope eyepiece and magnify the subject. As the correct alignment of these two mirrors is imperative for high performance regular maintenance is recommended.

All reflectors regardless of their origin are susceptible to knock and bumps over time that can cause these mirrors to move out of alignment. The Skywatcher OPCOLL fits in your telescopes focuser to aid in re-collimation. See the manual that came with your Skywatcher telescope.

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.

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. 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

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, 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. Make sure that all three small alignment screws
are tightened to secure the secondary mirror in place.

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.
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.
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.
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 a bright star close to the south celestial pole. 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.