Celestron Omni XLT

More Information  · Supplied Accessories  · Recommended Accessories  · Related Documents  · Images of Some Features Price $899.00 List Price $1,577.95 Highest Useful Magnification 300x Visual Limiting Magnitude 13.4 Focal Length 750mm Focal Ratio f/5 Resolution 0.77 arc seconds Aperture 5.9" Net Weight 49.5 lbs. Heaviest Single Component 21 lbs. Warranty 2 years

• 150mm f/5 achromatic refractor optics
• StarBright XLT multicoatings for the highest possible light transmission
• CG-4 German equatorial mount with ball bearings and stainless steel tripod
• 6 x 30mm finderscope
• 25mm 1.25” eyepiece (30x)
• 2-year warranty

    The Celestron Omni XLT 150R refractor combines quality big-aperture achromatic optics with a solid German equatorial mount – at a remarkably sensible price for a scope of its quality. It provides an excellent mix of performance, portability, stability, and features that any serious backyard astronomer can appreciate.

    For the observer whose interests are the fainter deep space objects, the big aperture and fast focal ratio of the Omni XLT 150R has a lot to offer. Binary stars and globular star clusters are particularly well-resolved due to the large unobstructed aperture. Star colors are vivid, with the contrasting colors of many binary systems showing nicely. The brighter nebulas and galaxies stand out against a darker sky background than is possible in a comparably-priced reflector with its light-scattering diagonal mirror.

    While it is exceptional for observing outside the solar system, its diffraction-free views of subtle lunar and planetary details are also quite good. Given suitable filtration to cut down on the scope’s brightness and the chromatic aberration visible in every large aperture achromatic refractor, solar system objects are brought to vivid life in the eyepiece.

   CG-4 mount

This Telescope’s Optical System . . .

• Refractor optics: 5.9" (150mm) aperture, 750mm focal length, f/5 achromatic doublet lens using aspheric lens shaping technology for images that have virtually no spherical aberration. The lens cell is fully collimatable for optimum sharpness. The length of the 16 pound optical tube is a very manageable 34".

• Starbright XLT multicoated optics: Fully coated on all air-to-glass surfaces with multiple layers of magnesium fluoride and hafnium dioxide antireflection coatings for the highest possible light transmission and contrast. They are the same coatings used on Celestron’s largest most expensive optical systems.

• Lens cap/aperture stop: A protective lens cap is provided to cover the objective lens of the telescope and keep it dust-free when the scope is not in use. This lens cap has a built-in aperture stop in the center. When observing the Moon and planets, leaving the lens cap on the telescope with the aperture stop removed will reduce the scope’s chromatic aberration (the faint halo of violet light or “spurious color" visible around very bright objects in all achromatic refractor telescopes). The scope’s resolution will be slightly reduced, but eliminating the spurious color provides a generally more pleasing image for most observers. The lens cap should always be completely removed when observing faint deep sky objects such as nebulas and galaxies, where aperture (light-gathering) is essential and chromatic aberration is not an issue.

• Dew shield: Slows the formation of dew on the lens in cold weather to extend your undisturbed observing time. Also improves visual and photographic contrast by shielding the lens from off-axis ambient light (the neighbor’s yard light, moonlight, etc.)

• Rack and pinion focuser: 2" focuser, with 1.25" eyepiece adapter. Dual focusing knobs with rubber gripping surfaces for precise image control with either hand. The large focus knobs are easy to operate, even while wearing gloves or mittens in cold weather. The eyepiece holder has built-in T-threads for attaching an optional T-ring and camera for prime focus photography.

• Star diagonal: 90° viewing angle prism-type 1.25" star diagonal.

• Eyepiece: Fully multicoated low power 1.25" 25mm (30x) eyepiece with a wide 1.67° field of view (three and a third times the diameter of the full Moon).

• Finderscope: 6 x 30mm straight-through achromatic design, with a wide 7° field of view. To focus, loosen the trim ring behind the objective lens cell, screw the lens cell in or out until the stars are sharp, then tighten the trim ring to lock in the correct focus.

• Software: Comes with TheSky Level 1 sky-charting CD-ROM that has a database of 10,000 stars and objects it can plot and display on your Windows-based computer screen. That’s enough solar system and deep space detail to keep you busy observing for years, yet not so much that you’re overwhelmed by charts showing much more detail than your scope can usefully reveal. Custom sky chart printing lets you print out eyepiece finder charts to use with your telescope to help you locate and identify the planets and many famous and faint deep space nebulas, galaxies, and star clusters by star-hopping from object to object using your scope’s slow motion controls. There are 75 full color images of well-known celestial objects to help you identify them through your scope.

This Telescope’s Mount . . .

• CG-4 German equatorial mount: The mount has setting circles in both right ascension and declination, worm gear drives and manual slow motion controls in both axes, a latitude scale and fine adjustment controls in both altitude and azimuth, two counterweights totaling 11 pounds, and more. Ball bearings provide smooth tracking in both axes. An optional dual axis DC drive/drive corrector is available for no-hands tracking of celestial objects and photography. It is not possible to upgrade to a computerized go-to drive system. For more details, click on the “mount" icon above.

• Adjustable height tripod: The tripod has 1.75" diameter steel legs with a center leg brace for rigidity. The tripod adjusts over a height range from 33" to 47". Vibration damping characteristics are excellent. The center leg brace is drilled to form a convenient accessory tray that holds 1.25" and 2" eyepiece to keep them up out of the dew-soaked grass.

• Dovetail tube mount: The scope’s optical tube rings are connected to a mounting plate that slips into a dovetail groove on the mount’s equatorial head. Setup and takedown times are exceptionally fast, as a single large hand-tighten knob holds the optical tube in place. A second lock knob prevents the tube from sliding off the mount should the hand-tighten knob accidentally loosen while observing.

• Two-year warranty: All Celestron telescopes have a two-year warranty, double that of competitive scopes.

What can you see through this 150mm Celestron refractor?

    With a big 6" aperture, a short focal length of only 750mm, and a light grasp 459 times that of the sharpest dark-adapted eye, the scope is capable of producing bright wide-field images of the faint fuzzies outside the solar system – nebulas, galaxies, open star clusters, and more.

    Even those objects requiring high power and high contrast – globular clusters, close binary star pairs, lunar and planetary images, etc. – will look good through this achromatic scope, although some optional accessories will be helpful to get the most out of the scope. Because of the large aperture, lunar and planetary images will be quite bright. A neutral density (“Moon") filter will be a help in reducing the high solar system image brightness that might otherwise wash out faint and subtle low-contrast details on the Moon and planets. Using optional eyepieces and/or a Barlow to boost the magnification, you can see subtle solar system details that are virtually invisible in smaller aperture scopes. You can study lunar craters, rilles, mountain ranges, and low contrast lunar ray detail. With reasonable seeing conditions, detail in Jupiter’s cloud belts and the Great Red Spot (actually closer in color to the Faint Pink Spot at this point in time) are visible, as are dusky markings on the face of Saturn and Cassini’s division in Saturn’s brilliant rings.

    Chromatic aberration is unavoidably present in this large aperture/fast focal ratio scope when viewing very bright objects, as it is in all achromatic refractor telescopes, but using the lens cap/aperture stop mentioned above will reduce its visibility. In addition, the use of an optional aberration-reducing minus violet filter (#CCBF) will also help eliminate the violet halo of spurious color around the Moon, planets, and bright stars (which many people find unobjectionable in any case).

    Optically and mechanically refined, and very reasonable in cost for a 6" refractor, this Celestron Omni XLT 150R has enough optical performance to keep you busy for the rest of your life.