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Equipment review
Celestron revives
a classic scope
With the Omni XLT 127, Celestron has made its signature
5-inch scope even better. by Raymond Shubinski
C
elestron is famous for its highquality Schmidt-Cassegrain telescopes. Anyone who has attended
a large star party has seen a variety of
these scopes. Now Celestron has updated
one of its all-time favorites — what had
been the company’s traditional 5-inch
telescope — as the Omni XLT 127.
For this new incarnation, Celestron
replaced the old orange-and-black finishes with a deep metallic-blue barrel and
powder-coated white end caps. The XLT
127 comes with a German equatorial
mount, slow-motion controls, and a
high-quality stainless steel tripod. The
package also includes a 25mm eyepiece
and a 11⁄4" star diagonal.
Out of the box
I found setting up this scope easy. The
equatorial mount, however, may baffle
some first-time telescope owners. Fortunately, the XLT 127 comes with a detailed
manual. I strongly suggest that newcomers to observing (and even old hands)
read the instructions.
Two problems most users have with a
German mount is balancing
The optics of the Omni XLT 127 are
Schmidt-Cassegrain. Celestron
added its StarBright coatings to
enhance image contrast. The optical tube has a focal length of
1,250 millimeters and a focal
ratio of f/9.84.
the scope and lining it up with the
North Celestial Pole. You’ll find
detailed answers to both issues in the
information supplied and at Celestron’s
web site (www.celestron.com). The Omni
XLT 127 also comes with a level-one
copy of TheSky software. This nice addon will prove helpful for planning an evening of observing.
Five inches (127mm) of aperture
means this telescope is for casual skygazing. With its 1250mm focal length,
inserting the 25mm eyepiece gives a
comfortable magnification of 50. You’ll
want to add other eyepieces with a range
of focal lengths to fully utilize the Omni
XLT’s potential.
The XLT 127 is mechanically stable. The focus is smooth, and the
right ascension and declination
motions have little or no backlash. The mount has ball bearings in both axes to aid in its
smooth motion. The steel
tripod is also steady. I
noticed almost no vibration despite the unit’s
light weight.
I would recommend using a larger
finder scope than
the one provided.
The 6x30 finder
scope sits away
from the main
© 2009 Kalmbach Publishing Co. This material
be reproduced in any form without permission
publisher. www.Astronomy.com
Celestron’s Omni XLT
127 is a complete
5-inch telescope system. It has an equatorial mount, sturdy steel
tripod, counterweights, 11⁄4" star diagonal, 25mm eyepiece,
and finder scope.
may not
from the
Specifications
Omni XLT 127
Optical design: Schmidt-Cassegrain
Aperture: 5 inches (127mm)
Focal length: 1,250mm
Focal ratio: f/9.84
Mount: Omni CG-4 equatorial
Optical tube length: 11 inches (279mm)
Optical tube weight: 6.5 pounds (3 kilograms)
Equatorial mount weight: 21 pounds
(9.5 kg)
Tripod weight: 12.5 pounds (5.7 kg)
Also includes: 6x30 finder scope, 11⁄4"
star diagonal, 25mm eyepiece (50x),
counterweights, slow-motion cables
Price: $659
tube’s body, but with only a 30mm aperture, faint objects are hard to see.
The Omni XLT 127 is not a computerdriven scope. However, a number of
upgrades are available. One of the most
useful is the dual-axis motor drive, which
allows for tracking in right ascension and
adjustments in declination.
Sky-testing the scope
Observing on a clear winter night in
southern Nevada has some real advantages, such as the moderate temperature
and lack of atmospheric aerosols. The
one major disadvantage, however, is the
serious light pollution. Despite that, the
XLT 127 performed well.
To check for any problems with spherical aberration, I used a short-focallength eyepiece. If I collimated the scope
well, a defocused medium-bright star
should show a nice “target” pattern of
light rings with distinct dark areas
Raymond Shubinski is a contributing editor
of Astronomy who observes from Henderson,
Nevada. He loves telescopes.
The rear of the telescope accepts
the star diagonal. The single focuser
knob lies just to its upper right in
this picture. A metal arm holds
the 6x30 finder scope at a
comfortable distance from
the main tube. Equipment photos:
Astronomy: William Zuback
between the bright circles. The XLT 127
showed perfect sets of rings as I ran the
focus inward and outward.
For my first celestial targets, I pointed
the scope at some of my favorite double
stars. Delta (δ) Orionis split easily
through the 25mm. Through the Omni
XLT, each of the stars was a beautiful
stark white with distinct black between
them. A more challenging double is Pollux (Beta [β] Geminorum). Its two stars
lie only 5" apart and are similar in brightness. I had to use a 13mm eyepiece (96x)
to split the pair. Again, the contrast
between the stars impressed me.
I then moved to a few star clusters.
Through the 25mm eyepiece, I had no
trouble finding M41 in Canis Major. I
could see a lovely yellowish-red star near
the center of the cluster, which gives a
nice contrast to the field of stars.
M35, which lies near the foot of the
twin Castor, was another marvelous
object even with all of the sky glow. The
cluster was easy to find with low power
and spread out in the field of view.
Finally, I turned the XLT 127 on the Beehive Cluster (M44) in Cancer. Switching
to a 36mm eyepiece (35x) allowed me to
sweep up the entire cluster at once.
Saving the best for last, I turned the
scope toward the Orion Nebula (M42).
Using Celestron’s 25mm eyepiece, I let
M42 drift into the field of view. As it
moved into the field, I could see the
“winglike” filaments spreading out from
the central area of the nebula. The
famous Trapezium of stars near the nebula’s center was easy to spot. Later, as the
Moon
rose, I used
a 17mm (74x)
and then a 10mm
(125x) eyepiece. In a
testament to the optical
quality of the Omni
XLT, the lunar
image held up well.
The improved
StarBright
coatings
enhance the
contrast and
provide sharp
images.
Solid bottom line
I found the Omni XLT
127 to be a high-quality and easily transportable telescope to take in search of
dark skies. With a barrel length of only
11 inches (279mm), the optical tube
assembly fits nicely into a small duffle
bag. You can disassemble the tripod and
place it on the backseat of your car. The
5-inch Celestron has been a favorite
among amateur astronomers since its
introduction in 1971. The newest version
is a great upgrade of an old standard.
Contact information
Celestron
2835 Columbia St.
Torrance, California 90503
[t] 310.328.9560
[w] www.celestron.com
NASA/ESA/A. Nota, STScI/ESA
www.Astronomy.com
55
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