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Focusing the Finder Scope
If, when looking through the finder scope, the images
appear somewhat out of focus, you will need to refocus the
finder scope for your eyes. Loosen the lock ring located
behind the objective lens cell on the body of the finder
scope (see Figure 5). Back the lock ring off by a few turns,
for now. Refocus the finder scope on a distant object by
threading the objective lens cell in or out on the finder scope
body. Precise focusing will be achieved by focusing the find-
er scope on a bright star. Once the image appears sharp,
retighten the lock ring behind the objective lens cell. The
finder scope's focus should not need to be adjusted again.
Objective lens
Focus
lock ring
Spring-loaded
tensioner
Figure 5. The 6x30 finder scope and bracket.
5. Setting Up and Using
the Equatorial Mount
When you look at the night sky, you no doubt have noticed that
the stars appear to move slowly from east to west over time. That
apparent motion is caused by the Earth's rotation (from west to
east). An equatorial mount (Figure 2) is designed to compensate
for that motion, allowing you to easily "track" the movement of
astronomical objects, thereby keeping them from drifting out of
the telescope's field of view while you're observing.
This is accomplished by slowly rotating the telescope on its
right ascension axis, using only the R.A. slow-motion cable. But
Figure 6. To find Polaris in the night sky,
look north and find the Big Dipper. Extend
an imaginary line from the two "Pointer
Stars" in the bowl of the Big Dipper. Go
about five times the distance between those
stars and you'll reach Polaris, which lies
within 1° of the north celestial pole (NCP).
Alignment
thumb screws
Eyepiece
Big Dipper
(in Ursa Major)
first the R.A. axis of the mount must be aligned with the Earth's
rotational (polar) axis - a process called polar alignment.
Polar Alignment
For Northern Hemisphere observers, approximate polar
alignment is achieved by pointing the mount's R.A. axis at the
North Star, or Polaris. It lies within 1° of the north celestial
pole (NCP), which is an extension of the Earth's rotational
axis out into space. Stars in the Northern Hemisphere appear
to revolve around the NCP.
To find Polaris in the sky, look north and locate the pattern of
the Big Dipper (Figure 6). The two stars at the end of the
"bowl" of the Big Dipper point right to Polaris.
Observers in the Southern Hemisphere aren't so fortunate to
have a bright star so near the south celestial pole (SCP). The
star Sigma Octantis lies about 1° from the SCP, but it is bare-
ly visible with the naked eye (magnitude 5.5).
For general visual observation, an approximate polar align-
ment is sufficient.
1. Level the equatorial mount by adjusting the length of the
three tripod legs.
2. Loosen the latitude lock t-bolt. Turn the latitude adjustment
t-bolt and tilt the mount until the pointer on the latitude
scale is set at the latitude of your observing site. If you
don't know your latitude, consult a geographical atlas to
find it. For example, if your latitude is 35° North, set the
pointer to 35. Then retighten the latitude lock t-bolt. The
latitude setting should not have to be adjusted again unless
you move to a different viewing location some distance
away.
3. Loosen the Dec. lock knob and rotate the telescope opti-
cal tube until it is parallel with the R.A. axis, as it is in
Figure 1. The pointer on the Dec. setting circle should read
90°, Retighten the Dec. lock lever.
4. Loosen the azimuth lock knob at the base of the equatori-
al mount and rotate the mount so the telescope tube (and
R.A. axis) points roughly at Polaris. If you cannot see
Polaris directly from your observing site, consult a com-
pass and rotate the mount so the telescope points North.
Retighten the azimuth lock knob.
The equatorial mount is now polar-aligned for casual observ-
ing. More
precise
polar
astrophotography.
Little Dipper
(in Ursa Minor)
N.C.P.
Polaris
alignment
is
required
Cassiopeia
for
7
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