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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 Keep your eyes on the sky and renew your ASTRONOMY subscription Don’t break your link to the leading astronomy magazine on the market. Renew your subscription and continue to receive the insightful astronomical information that fills every issue: New-product listings Expert observing tips Field tests: telescopes, cameras, binoculars, eyepieces, accessories Monthly pullout star maps And exclusive online access to Star Atlas, Star Dome Plus, The Sky this Month, Ask Astro archives, videos, image galleries, product information, and more! RENEW TODAY! www.Astronomy.com/ASYRENEW Plus, why not share your enthusiasm? It’s easy to send someone a gift subscription today! 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