Orion 9768 Instruction Manual page 4

a.
b.
d.
Figure 4.
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) Here, the secondary mirror is
centered in the collimation cap, but it needs to be adjusted (tilted) so
that the entire primary mirror is visible. (d) With the collimation target
on the front of the tube, the secondary mirror is correctly aligned, but
the primary mirror still needs adjustment. When the primary mirror
is correctly aligned, the target's center will coincide with the primary
mirror center mark, as in (e).
the three small alignment setscrews in the center hub of the
secondary mirror holder several turns. Now keep the mirror
stationary (be careful not to touch the surface of the mirror!),
while turning the center screw with a Phillips head screwdriver
(Figure 5b). Turning the screw clockwise will move the second-
ary mirror toward the front opening of the optical tube (to the
left in the collimation cap), while turning the screw counter-
clockwise will move the secondary mirror toward the primary
mirror (to the right in the collimation cap). When the second-
ary mirror is best centered in the collimation cap, rotate the
secondary mirror until the reflection of the primary mirror is
4
Primary mirror
center mark
c.
e.
Figure 5b.
To adjust the secondary mirror position left and right
in the collimation cap, loosen or tighten the Phillips head screw
in the center of the mirror holder, while holding the mirror itself
stationary.
as centered in the secondary mirror as possible. It may not be
perfectly centered, but that is OK for now. Tighten the three
small alignment screws equally to secure the secondary mir-
ror in that position.
If the entire primary mirror reflection is not visible in the sec-
ondary mirror, as in Figure 4c; you will need to adjust the tilt
of the secondary mirror. This is done by alternately loosening
one of the secondary mirror holder's three alignment set-
screws while tightening the other two, as depicted in Figure
6. The goal is to center the primary mirror reflection in the
secondary mirror, as in Figure 4d. The primary mirror center
mark greatly aids in doing this.
Once the secondary mirror itself and the reflection of the pri-
mary mirror (and center mark) are centered in the collimation
cap, the secondary mirror is collimated.
Figure 5a.
To adjust the
secondary mirror
position up and
down in the
collimation cap,
loosen the two
Phillips head screws
that attach the entire
secondary mirror
holder to the tube,
and move the mirror
holder in the slots.