Orion SPACEPROBE 9851 - Manual (Page 10)

10
the counterweight shaft will be oriented somewhere between
vertical and horizontal.
The key things to remember when pointing the telescope is
that a) you only move it in R.A. and Dec., not in azimuth or
latitude (altitude), and b) the counterweight and shaft will not
always appear as it does in Figure 1. In fact, it almost never
will!
6. Collimating the Optics
(Aligning the Mirrors)
Collimation is the process of adjusting the mirrors so they
are perfectly aligned with one another. Your telescope’s
optics were aligned at the factory, and should not need
much adjustment unless the telescope is handled roughly.
Accurate mirror alignment is important to ensure the peak
performance of your telescope, so it should be checked reg-
ularly. Collimation is relatively easy to do and can be done in
daylight.
To check collimation, remove the eyepiece and look down
the focuser drawtube. You should see the secondary mirror
centered in the drawtube, as well as the reflection of the pri-
mary mirror centered in the secondary mirror, and the reflec-
tion of the secondary mirror (and your eye) centered in the
reflection of the primary mirror, as in figure 8a. If anything is
off-center, as in figure 8b, proceed with the following collima-
tion procedure.
the Collimation Cap and Mirror Center Mark
Your SpaceProbe 130 EQ comes with a collimation cap. This
is a simple cap that fits on the focuser drawtube like a dust
cap, but has a hole in the center and a silver bottom. This
helps center your eye so that collimation is easy to perform.
Figures 8b through 8e assume you have the collimation cap
in place.
In addition to providing the collimation cap, you’ll notice a tiny
ring (sticker) in the exact center of the primary mirror. This
“center mark” allows you to achieve a very precise collima-
tion of the primary mirror; you don’t have to guess where the
center of the mirror is. You simply adjust the mirror position
(described below) until the reflection of the hole in the col-
limation cap is centered inside the ring. This center mark is
also required for best results with other collimating devices,
such as Orion’s LaserMate Laser Collimator, obviating the
need to remove the primary mirror and mark it yourself.
NOTE: The center ring sticker need not ever be removed
from the primary mirror. Because it lies directly in the
shadow of the secondary mirror, its presence in no
way adversely affects the optical performance of the
telescope or the image quality. That might seem counter-
intuitive, but it’s true!
Aligning the Secondary Mirror
With the collimation cap in place, look through the hole in the
cap at the secondary (diagonal) mirror. Ignore the reflections
for the time being. The secondary mirror itself should be cen-
tered in the focuser drawtube, in the direction parallel to the
length of the telescope. If it isn’t, as in figure 8b, it must be
adjusted. Typically, this adjustment will rarely, if ever, need to
be done. It helps to adjust the secondary mirror in a brightly
lit room with the telescope pointed toward a bright surface,
such as white paper or wall. Placing a piece of white paper
in the telescope tube opposite the focuser (i.e., on the other
side of the secondary mirror) will also be helpful in collimat-
ing the secondary mirror. Using a 2mm Allen wrench, loosen
the three small alignment set screws in the center hub of
the 4-vaned spider several turns. Now hold the mirror holder
stationary (be careful not to touch the surface of the mirrors),
while turning the center screw with a Phillips head screw-
driver (see Figure 9). Turning the screw clockwise will move
the secondary mirror toward the front opening of the optical
tube, while turning the screw counter-clockwise will move the
secondary mirror toward the primary mirror.
When the secondary mirror is centered in the focuser draw-
tube, rotate the secondary mirror holder until the reflection
of the primary mirror is as centered in the secondary mirror
as possible. It may not be perfectly centered, but that is OK.
Now tighten the three small alignment screws equally to
secure the secondary mirror in that position.
Figure 7. This illustration shows the telescope pointed in the four cardinal directions: (a) north, (b)south, (c) east, (d) west. Note that the
tripod and mount have not been moved; only the telescope tube has been moved on the R.A. and Dec. axes.
b. d. a. c.