Orion 8 EQ - Manual (Page 9)

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The reticle of the polar axis finder scope has a tiny star map
printed on it that makes precise polar alignment quick and
easy. If you do not have a clear view of Polaris from your
observing site, you will not be able to use the polar-axis finder
to precisely polar align the telescope.To align the mount using
the polar axis finder scope, follow these instructions:
1. Approximately polar-align the mount as outlined in the pro-
cedure earlier.
2. Loosen the Dec. lock lever and rotate the optical tube on
the declination axis so that the tube is at a 90° to the right
ascension axis (Figure 11). Tighten the Dec. lock lever.
Remove the cap on the front opening of the equatorial mount
(Figure 7). Focus the polar finder by rotating the eyepiece.
Now, sight Polaris in the polar axis finder scope. If you have
followed the approximate polar alignment procedure accurate-
ly, Polaris will probably be within the field of view. If not, move
the tripod left-to-right, and adjust the latitude up-and down
until Polaris is somewhere within the field of view of the polar
axis finder scope.
Shine a red flashlight down the front end of the polar finder to
illuminate the reticle within the field of view. Make sure the
flashlight shines in at an angle, so as not to block the polar
finder’s field of view. It may be helpful to have a friend hold the
flashlight while you look through the polar finder. Note the con-
stellation Cassiopeia and the Big Dipper in the reticle. They do
not appear to scale, but they indicate the general positions of
Cassiopeia and the Big Dipper relative to the north celestial
pole (which is indicated by the cross at the center of the reti-
cle). Rotate the reticle so the constellations depicted match
their current orientation in they sky when viewed with the
naked eye. To do this, release the R.A. lock lever and rotate
the main telescope around the R.A. axis until the reticle is ori-
ented with sky. For larger optical tubes, you may need to
remove the tube from the mount to prevent it from bumping
into the mount. Once the reticle is correctly oriented, use the
right ascension lock lever to secure the mount’s position.
Now use the azimuth adjustment knobs (Figure 9) and the lat-
itude adjustment L-bolts (Figure 7) on the mount to position
the star Polaris inside the tiny circle marked “Polaris” on the
finder’s reticle. You must first loosen the knob underneath the
equatorial mount on the center support shaft to use the
azimuth adjustment knobs. Once Polaris is properly posi-
tioned within the reticle, you are precisely polar aligned.
Note: From this point on in your observing session, you
should not make any further adjustments in the azimuth
or the latitude of the mount, nor should you move the tri-
pod. Doing so will undo the polar alignment. The
telescope should be moved only about its right ascen-
sion and declination axes.
Additional Note Regarding Focusing the Polar
Axis Finder Scope
The polar axis finder scope is normally focused by simply
rotating the eyepiece focus ring. However, if after adjusting the
focus ring you find that the image of the reticle is sharp, but
the stars are out of focus, then you must adjust the focus of
the polar axis finder’s objective lens. To do this, first remove
the polar axis finder from the mount. Look through the polar
axis finder at a star (at night) or distant object at least 1/4 mile
away (during daylight). Use the eyepiece focus ring to bring
the reticle into sharp focus. Now, loosen the focus lock ring
(Figure 10a) and thread the entire objective end of the finder
inwards or outwards until images appear sharp. Re-tighten the
focus lock ring. Once the polar axis finder’s objective lens is
focused, it should not need to be adjusted again.
Use of the Right Ascension and Declination Slow-
Motion Control Knobs
The right ascension (R.A.) and declination (Dec.) slow-motion
control knobs allow fine adjustment of the telescope’s position
to center objects within the field of view. Before you can use
the knobs, you must manually “slew” the mount to point the
telescope in the vicinity of the desired target. Do this by loos-
ening the R.A. and Dec. lock levers and moving the telescope
about the mount’s right ascension and declination axes. Once
the telescope is pointed close to the object to be viewed,
retighten both lock levers.
The object should now be visible somewhere in the tele-
scope’s finder scope. If it isn’t, use the slow-motion knobs to
scan the surrounding area of sky. When the object is visible in
the finder scope, use the slow-motion knobs to center it. Now,
look in the telescope’s eyepiece. If the finder scope is proper-
ly aligned, the object should be visible somewhere in the field
of view. Once the object is visible in the eyepiece, use the
slow-motion knobs to center it in the field of view.
Figure 11. The optical tube must be at a 90° angle to the
right ascension axis in order to view through the polar axis
finder