All About Space

Celestron Omni XLT 120

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A quality telescope that is easily accessoris­ed, this refractor is ideal for observing the Solar System and some bright deep-sky objects

For the price, the XLT 120 is of exceptiona­l quality, especially if you are a keen observer of Solar

System targets such as the planets and our Moon. Since you don’t need tools to set up the telescope, it takes a mere five to ten minutes to put it together.

The XLT 120 is a fine example of a small to medium-sized refractor, and this became evident when we turned it to a selection of objects in a relatively clear March night sky. We took advantage of a full Moon with the Celestron Omni, and popping the supplied 25mm eyepiece, which provides a magnificat­ion of 40x, into the 1.25” star diagonal, we were soon studying the lunar surface. The telescope’s lenses are of superb quality, manufactur­ed with StarBright XLT coatings to ensure bright and crystal-clear views as we toured craters and mare, as well as lunar rilles and mountains. Bright crater Aristarchu­s was a stunning sight, as were the craters Kepler, Copernicus and Tycho, whose rays, made when material was thrown up during their progenitor impacts, could easily be detected by the refractor.

As we slewed across the Moon’s surface, we noted the ease with which the German Equatorial mount allowed the telescope tube to move. The mount’s well-made stainless-steel tubular tripod legs are exquisite, providing excellent support to the telescope and a good, solid base when combined with the counterbal­ance for anyone wishing to try their hand at basic astrophoto­graphy.

Sadly, we did notice a small degree of colour fringing, or chromatic aberration, which gave bright objects a purple to blue colouring. For the cost of the telescope, we did expect this common flaw with refractor telescopes to be prevalent in the

XLT 120, but we were delighted to see that our views of the night sky were hardly affected. In fact, the chromatic aberration was so minor that we quickly forgot about this slight problem in the telescope’s optical system.

“We noted that views were sharp across a good proportion of the field of view”

The XLT 120 unfortunat­ely doesn’t come with a great deal of accessorie­s apart from the aforementi­oned diagonal and 25mm eyepiece. However, being versatile and having a useful maximum magnificat­ion of over 280x, the refractor will serve as a good instrument for years to come, ensuring that the observer, particular­ly a beginner, doesn’t outgrow it. The multi-coated 25mm eyepiece has very good eye relief and we were delighted to see that it, as with all Celestron eyepieces, is of excellent quality and build.

Putting the 6x30 finderscop­e to the test, we noted the clear and sharp views when we used it to guide us to the very bright star Sirius, which shines at magnitude -1.46. We noted that views were sharp across a good proportion of the field of view with only slight trailing off at the edges of the field. We were quick to move over to gas giant Jupiter and its four largest moons – Ganymede, Io, Callisto and Europa – and were impressed with the view as the gas giant’s disc popped into view and the satellites appeared as points of light. We did note a halo around the planet, which unfortunat­ely didn’t disappear until we popped in a filter.

With Venus in the sky, we took the opportunit­y to observe it. As with views of many bright objects, there was purple colour fringing around the planet’s bland disc. Red giant star Betelgeuse kept its stunning orange-red colour at 40x, while not too far away the Orion Nebula’s diffuse gas and the Trapezium star cluster were picked up easily with the additional help of averted vision.

We can highly recommend the XLT 120.

You don’t get a great deal in the way of accessorie­s, but you do get a decent optical system housed by a very well-built telescope tube combined with a sturdy mount. It might take some getting used to by novices, but it promises to last for many observing sessions.

 ??  ?? Right (main): The tube is of impressive build and the refractor’s optical system provides clear and sharp views of a variety of nightsky objects with only a degree of colour fringing
Right (main): The tube is of impressive build and the refractor’s optical system provides clear and sharp views of a variety of nightsky objects with only a degree of colour fringing
 ??  ?? Left: A heavyduty German Equatorial mount enables the telescope to be slewed smoothly, and combined with a sturdy tripod allows for a solid platform
Left: A heavyduty German Equatorial mount enables the telescope to be slewed smoothly, and combined with a sturdy tripod allows for a solid platform
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