Meade Instruments LX90 ACF/SC - Manual (Page 16)

16
OBSERVING
Observing By Moving the Telescope Manually
If you wish to observe a distant land object, such as a mountain top or a bird, you can
observe by merely pointing the telescope and looking through the eyepiece.
1. Loosen the telescope’s R.A. lock (Pg. 7, Fig. 1, 9) and Dec. lock (Pg. 7, Fig. 1, 6).
2. Move your telescope to observe distant street signs, mountains, trees, and other
structures. Use the viewfinder to to help site-in on an object.
3. Center the object with viewfinder’s cross hairs and then in the telescope eyepiece. When
the object is centered in your eyepiece, remember to re-tighten the R.A. and Dec. locks.
4. Practice focusing objects with the focus knob (Fig. 1, 8).
5. Once you get a feel for how your telescope moves and focuses, try to view something more
challenging, like a bird or a distant moving train.
NOTE: Viewing conditions vary widely from night-to-night and site-to-site.
Turbulence in the air, even on an apparently clear night, can distort images. Low-
power eyepieces, such as the Super Plössl 26mm supplied with your telescope, are
better suited to resolving images in poor viewing conditions.
You can also observe stars and objects in the night sky using this method, but note that objects
begin to slowly drift across the eyepiece field. This motion is caused by the rotation of the Earth.
As you become familiar with the AutoStar handbox operation, you can counteract the drift using
the automatic tracking feature in the AutoStar Setup menu (see
TO TRACK AN OBJECT
AUTOMATICALLY , page 18), or by using AutoStar's GO TO capabilities (see GO TO
SATURN , page 21).
Terrestrial Observing
The LX90 is an excellent high-resolution, terrestrial (land) telescope. Viewing terrestrial objects
requires looking along the Earth’s surface through heat waves. These heat waves often cause
degradation of image quality. Lower power eyepieces, like the Super Plössl 26mm
eyepiece, magnify these heat waves less than higher power eyepieces. Therefore, lower power
eyepieces provide a steadier, higher quality image. If the image is fuzzy or ill-defined, reduce
to a lower power eyepiece, where the heat waves do not have such an effect on image quality.
Observing in early morning hours, before the ground has built up internal heat, produces
better viewing conditions than during late afternoon hours.
Observing Using AutoStar’s Arrow Keys
You may observe land and astronomical objects using AutoStar’s Arrow keys to move the
telescope.
1. Tighten the Dec. and R.A. locks (Pg. 7, Fig. 1, 6 and 9).
IMPORTANT NOTE:
Objects appear
upside-down and
reversed left-for-right
when observed in the
eyepiece when
inserted directly into
the (straight-through)
eyepiece holder – with
the diagonal prism in
place, images will be
right-side-up, but
reversed left-for-right.
This image inversion is
of no consequence
when observing
astronomical objects
and, in fact, all
astronomical
telescopes yield
inverted images.
During terrestrial
observing, where a
fully correctly-oriented
image (right-side-up
and correct left-for-
right) is desirable, an
optional #928 45°
Erecting Prism is
available. See
OPTIONAL
ACCESSORIES,
page 42.
Too Much Power?
Can you ever have too much power? If the type of power you’re referring to is
eyepiece magnification, yes, you can! The
most common mistake of the
beginning observer is to “overpower” a telescope by using high magnifications
which the telescope and atmospheric conditions cannot reasonably support.
Keep in mind that a smaller, but bright and well-resolved image is far superior to
one that is larger, but dim and poorly resolved (see Figs. 7a and 7b). Powers
above 400X should be employed only under the steadiest atmospheric
conditions.
AutoStar can calculate the best eyepiece for you to use. Try out the “Eyepiece
Calc” feature in the Utilities menu.
Most observers should have three or four additional eyepieces to achieve the full
range of reasonable magnifications possible with the
LX90 telescopes. See
OPTIONAL ACCESSORIES , page 42.
LX90 TIPS
Fig. 7a and 7b : Jupiter:
Examples of the right
amount of magnification and
too much magnification.