Meade Instruments DS-2000 LNT - Manual (Page 14)

14
Choosing an Eyepiece
A telescope’s eyepiece magnifies the light gathered by the optical tube. Each eyepiece has a
focal length, expressed in millimeters, or “mm.” The smaller the focal length, the higher the mag-
nification. For example, an eyepiece with a focal length of 9mm has a higher magnification than
an eyepiece with a focal length of 25mm.
Your telescope comes supplied with a low-powered 25mm or 26mm eyepiece which gives a
wide, comfortable field of view with high image resolution. Always begin your observations with
this eyepiece.
Low power eyepieces offer a wide field of view, bright, high-contrast images, and eye relief dur-
ing long observing sessions. After an object is located and centered in the eyepiece, try switch-
ing to a higher power eyepiece to enlarge the image.
NOTE: Viewing conditions vary from night-to-night and from site-to-site. Turbulence in
the air, even on an apparently clear night, can distort images. If an image appears
fuzzy and ill-defined, return to a lower power eyepiece for a more well-resolved image.
The power, or magnification of a telescope is determined by the focal length of the telescope
and the focal length of the eyepiece being used. To calculate eyepiece power, divide the tele-
scope's focal length by the eyepiece's focal length. For example, you may wish to use a 25mm
eyepiece with the DS-2000 model DS-2114S. Look up the focal length of the DS-2114S under
SPECIFICATIONS: DS-2114S , page 33. The focal length is listed as 1000mm.
Telescope focal length divided by Eyepiece focal length = Eyepiece power
1000
Ö 25 = 40
The eyepiece power, or magnification is therefore 40X (approximately).
The Barlow Lens
Some Meade telescopes include a power multiplier called a Barlow lens. Consisting of a lens
mounted in a 4"-long (10cm) tube, the Barlow doubles or triples the power obtained when an
eyepiece is used alone. In the example above, a 25mm eyepiece results in 40X magnification
with the DS-2114S telescope; when this same eyepiece is used in conjunction with a 2x Barlow
lens, power is doubled to 80X. To use the Barlow, insert it into the diagonal prism (refractor
models only) or eyepiece holder, followed by the eyepiece.
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 tripod base lock knob ( 26, Fig. 1) and Altitude lock (6, Fig. 1), so
that the telescope can move freely.
2. Point your telescope at distant street signs, mountains, trees, and other structures. Use
Smartfinder to help site-in on an object.
3. Center the object using Smartfinder and then in the telescope eyepiece. When the object
is centered in your eyepiece, re-tighten the base and Altitude locks.
4. Practice focusing objects with the focus knob ( 1, Fig. 1).
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.
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 AUTO-
MATICALLY , page 18), or by using Autostar's GO TO capabilities (see GO TO SATURN , page 19).
Important Note: When
you look through your
telescope’s eyepiece,
the image might look
strange at first.
If you have a refracting
telescope, objects will
appear right-side-up, but
reversed left-for-right.
This will not make a
difference when
observing astronomical
objects, and in fact, all
astronomical telescopes
present inverted images.
During terrestrial
observing, when a
corrected image (right-
side up and correct left-
for-right) is desirable, an
optional Meade 45°
Erecting Prism is
available. See the
OPTIONAL
ACCESSORIES, page
29, or consult the
Meade Telescope
Catalog.
No means of correcting
the image is available for
reflecting telescopes—
the image will appear
upside down and
reversed left-for-right.