Orion XT6 User Manual

Page 11

1200 mm

= 120x

10 mm

The maximum attainable magnification for a telescope is
directly related to how much light its optics can collect. A tele-
scope with more light-collecting area, or aperture, can yield
higher magnifications than a smaller-aperture telescope. The
maximum practical magnification for any telescope, regard-
less of optical design, is about 60x per inch of aperture. This
translates to about 360x for the SkyQuest XT6, 480x for the
XT8, and 600x for the XT10. Of course, such magnifications
will only yield reasonable images if atmospheric conditions
are favorable.

More typically, useful magnifications will be limited to 200x or
less, regardless of aperture. This is because the Earth’s “see-
ing,” the atmosphere will be still and will yield the least amount
of distortion. On nights of poor seeing, the atmosphere will be
turbulent, which means different densities of air are rapidly
mixing. This causes significant distortion of the incoming light,
which prevents sharp views at high magnifications.

Keep in mind that as magnification is increased, the bright-
ness of the object being viewed will decrease; this is an
inherent principle of the physics of optics and cannot be
avoided. If magnification is doubled, an image appears four
times dimmer. If magnification is tripled, image brightness is
reduced by a factor of nine!

Use of 2-Inch Eyepieces (XT8 and XT10 only)

All SkyQuest telescopes are designed to accept eyepieces
with a barrel diameter of 1.25". The XT8 and XT10 have 2"
focusers that accept both 1.25" and optional 2" eyepieces. At
low magnifications, 2" eyepieces can provide a wider field of
view than standard 1.25" eyepieces. A wider field can be
desirable for viewing extended deep-sky objects that are too
large to fit within a narrower field of view.

To use 2" eyepieces, simply loosen the two large thumbscrews
on the 2" adapter that are just in front of the thumbscrew that
holds the provided 1.25" adapter in place. Once these thumb-
screws are loosened the adapter comes off, exposing the 2"
diameter focuser drawtube Now, insert your 2" eyepiece into
the drawtube and secure with the two thumbscrews loosened
previously, and you’re ready to observe.

Tube Balance

SkyQuest IntelliScope Dobsonians are designed to balance
with standard supplied accessories, such as an eyepiece and
a finder scope. But what if you want to use a larger finder
scope or a heavier eyepiece? Traditional Dobsonian designs
require the user to compensate by adding weight to the oppo-
site end of the telescope tube. Such counterweighting systems
can be expensive and unwieldy. The CorrecTension system of
the SkyQuest IntelliScope Dobsonians, however, solves the
finicky balance problem. The brake pads press against the alti-
tude bearings on the optical tube and increase the friction.
With CorrecTension, the added weight of front-end loads will
not adversely affect the balance of the telescope. Simply tight-
en the tensioning knob to balance any extra load.

Carrying the Telescope

Transporting the SkyQuest is easy to do. The tube uncouples
from the base and each component can be carried separate-
ly. The base has a handle for easy carrying. With the retaining
and tensioning knobs of the CorrecTension(XT) system hold-
ing the optical tube captive on the base, the entire telescope
can be carried as one unit. (This is not practical for the XT10
due to its hefty weight and size.) This requires some caution,
however. If the telescope is lifted improperly, the tube could
swing down and hit the ground.

First, point the optical tube straight up (vertical). Remove any
eyepieces from the telescope and eyepiece rack, and place
them in an eyepiece case. Grasp the handle on the front of
the base with one hand while supporting the telescope tube
vertically with the other (Figure 17). Now, lift the telescope by
the handle. Once the telescope is in the horizontal position,
you can carry the entire unit with one hand while supporting
the optical tube with the other hand.

If you wish to carry the optical tube and base separately, sim-
ply unthread the retaining and tensioning knobs until they are
free of the base and optical tube (make certain spacer does
not fall off the retaining knob). Lift the tube off the base then

Figure 17.

Picking up and

carrying the SkyQuest IntelliScope
as a single unit (with tube held
captive on the base) requires
some caution.

(a)

First, position

the tube vertically. Then grasp the
handle on the base with one hand
while supporting the tube with the
other. This ensures that the tube
will not swing down and impact the
ground

(b)

With knees bent,

slowly lift the base while
supporting the tube.

(c)

As you

lift, continue to support the tube
with one hand to keep it parallel
with the ground. Make sure you
are comfortable with the weight of
the whole assembly before
attempting the carry it!