Orion SPACE PROBE 9843 - Manual (Page 11)

8. specifications
Optical tube: Steel
Primary mirror diameter: 76mm
Primary mirror coating: Aluminum with silicon dioxide (SiO
2
)
overcoat
Secondary mirror minor axis: 19.9mm
Focal length: 700mm
Focal ratio: f/9.2
Focuser: Rack and pinion, accepts 1.25” eyepieces
Eyepieces: 25mm and 10mm Explorer II eyepieces, 1.25”
Magnification: 28x (with 25mm) and 70x (with 10mm)
Mount: German Equatorial, EQ-1
Tripod: Aluminum
Weight: 16.6 lbs.
Motor drive: Optional
appendix a: collimation—
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 adjust-
ment unless the telescope is handled roughly. Accurate mir-
ror alignment is important to ensure the peak performance of
your telescope, so it should be checked regularly. 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 cen-
tered in the drawtube, as well as the reflection of the primary
mirror centered in the secondary mirror, and the reflection of
the secondary mirror (and your eye) centered in the reflection
of the primary mirror, as in Figure 8a. If anything is off-center,
proceed with the following collimation procedure.
the collimation cap and Mirror center Mark
Your SpaceProbe 3 comes with a collimation cap. This is a sim-
ple 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 collima-
tion 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
ad versely 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. 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 sec-
ondary mirror) will also be helpful in collimating the second-
ary mirror. Use a small Phillips head screwdriver to loosen the
three small alignment screws in the center hub of the 3-vaned
spider several turns. Now hold the mirror holder stationary (be
careful not to touch the surface of the mirrors), while turning
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