Orion XT10 - Manual (Page 9)

9
Setting the Altitude Tension Level
The telescope should move smoothly with just gentle hand
pressure. While azimuth friction is not adjustable, the altitude
friction can be adjusted to the desired level by turning the alti-
tude tension knob (Figure 10). Note that altitude tension knob
is the knob just above the IntelliScope Controller Port. The
knob on the opposite side of the base is merely a retaining
knob; it does not affect altitude tension.
Adjustable tension is a feature of the SkyQuest’s exclusive
springless CorrecTension Friction Optimization system.
CorrecTension adds just the right amount of friction to keep
the telescope tube in proper balance, even when other acces-
sories are added on, such as a barlow lens or a heavier
eyepiece.
A good way to set the altitude tension is to point the telescope at
about a 45° angle with the eyepiece and finder scope removed.
Loosen the altitude tension knob until the front of the optical
tube starts to drift upward. As it does so, tighten the tension
knob just enough to make the tube stop drifting (Figure 15).
When the eyepiece and finder scope are replaced, the motion
should be ideal -- not too stiff, not too loose.
You will want to be able to “track” the motion of celestial
objects while viewing them by making small movements of
the telescope without experiencing jerking (too much tension)
or overshooting of the desired position (too little tension).
Focusing the Telescope
With the 25mm Sirius Plössl eyepiece in the focuser and
secured with the thumbscrew(s), move the telescope so the
front (open) end is pointing in the general direction of an
object at least 1/4-mile away. Now, with your fingers, slowly
rotate one of the focusing knobs until the object comes into
sharp focus. Go a little bit beyond sharp focus until the image
just starts to blur again, then reverse the rotation of the knob,
just to make sure you've hit the exact focus point.
If you have trouble focusing, rotate the focusing knob so the
drawtube is in as far as it will go. Now look through the eyepiece
while slowly rotating the focusing knob in the opposite direction.
You should soon see the point at which focus is reached.
The thumb screw on the top of the body of the focuser (Figure
13) will lock the focuser drawtube in place once the telescope
is properly focused. Before focusing, remember to first loosen
this thumb screw. Do not loosen the thumb screw too much
as there must be some tension to keep the drawtube secure
within the focuser.
If you find the drawtube tension when focusing is either too
tight (focus knob is difficult to turn) or too loose (image shifts
when focusing), you can adjust it by tightening or loosen-
ing the two drawtube tensioning set screws on the focuser.
These are the two small set screws located on either side
of the focus lock thumb screw. Adjusting these set screws
requires a 1.5mm hex key.
Viewing with Eyeglasses
If you wear eyeglasses, you may be able to keep them on
while you observe, if your eyepieces have enough eye relief
to allow you to see the whole field of view. You can try this by
looking through the eyepiece first with your glasses on and
then with them off, and see if the glasses restrict the view
to only a portion of the full field. If they do, you can easily
observe with your glasses off by just refocusing the telescope
the needed amount. If you suffer from severe astigmatism,
however, you may find images noticeably sharper with your
glasses on.
Aligning the Finder Scope
The finder scope must be aligned accurately with the tele-
scope for proper use. To align it, first aim the main telescope
in the general direction of an object at least 1/4-mile away
- the top of a telephone pole, a chimney, etc. Position that
object in the center of the telescope’s eyepiece.
The finder scope uses a spring-loaded bracket that makes
alignment of the finderscope very easy. As you turn either of
the thumbscrews, the spring in the bracket’s tensioner moves
in and out to keep the finder scope secure in the bracket.
Note: The image in both the finder scope and the main
telescope will appear upside-down (rotated 180°). This is
normal for finder scopes and reflector telescopes (see
Figure 16).
Now look through the finder scope. Ideally, the object should
be within the field of view. If not, then coarse adjustments to
the alignment thumbscrews will be needed. Once the image
is in the finder scope’s field of view, you will now use the align-
ment thumbscrews to center the object on the intersection of
the crosshairs. By loosening one alignment thumbscrew, you
change the line of sight of the finder scope. Continue making
adjustments to the alignment thumbscrews until the image in
both the finder scope and the telescope’s eyepiece is exactly
centered.
Figure 15. Adjust the tensioning knob until the altitude balance is
just right. The telescope should move easily in altitude without drifting
when you let go.