CELESTRON OMNI XLT AZ 102
Boasting a first-class finish, this refractor offers the serious sky-watcher clear, magnified views of the Solar System
With the Celestron Omni XLT Omni 102, the sky-watcher gets a refractor that exudes quality. Aimed at intermediate-level astronomers with a reasonable knowledge of telescopes due to its complex German equatorial mount, this beautifully finished instrument promises to last for many years with a minimum level of maintenance.
The Omni 102 features high-quality optics – painted with Celestron’s StarBright XLT coating to maximise light transmission – on the finest grade of glass. The optical system also makes use of aspheric shaping technology to minimise spherical aberration, a visual defect where incoming light is focused at different points. The result is that resolution and clarity are affected, causing blurry views of the night sky.
The refractor comes with a 25mm eyepiece, 1.25-inch star diagonal, heavy-duty stainless-steel tripod, accessory tray, spirit level, Starry Night Special Edition software and a 6x30 finderscope.
That’s a good amount of accessories to get started with, but the telescope will need further eyepieces to reach the optical system’s highest and lowest useful magnifications of 240x and 15x.
On unboxing, we noted that the Omni 102 is of exceptional quality and design. Finished in a gunmetal-blue pearl with white accents, the telescope’s high-quality finish is the centrepiece of this instrument. Slow-motion controls are included for fine-tuned night-sky navigation.
Since you don’t need tools or fiddly screws and bolts to set up the telescope, it takes a mere five to ten minutes to put the Omni 102 together. The overall build is stable, with no sign of shaking or toppling over, and peering into the objective lens, the glass is beautifully coated. No residue of oil or glue was evident anywhere on the components.
One minor annoyance is the rack-and-pinion focuser. While it’s fashioned from high-quality metal and performs well, these focusers have a tendency to slip when holding heavy eyepieces and supporting cameras. We recommend replacing it with a Crayford focuser for optimum performance and fine-tuning your views.
The Omni 102 weighs 6.26 kilograms, making it less than portable for those looking to travel beyond their backyard – if you’re a sky-watcher who likes to chase the darkest skies, then we recommend either searching for a more portable option or having a vehicle to hand for transportation.
Unfortunately, the Omni 102 doesn’t come with a wide range of observing accessories apart from the star diagonal, finderscope and 25mm eyepiece. But being versatile and having a useful maximum magnification of over 240x, the refractor will serve as a good instrument for years to come – an amateur astronomer won’t outgrow it for some time. The multi-coated 25mm eyepiece has very good eye relief, and we were delighted to see that it’s of excellent quality and build – just like the telescope it slots into.
“The telescope’s high-quality finish is the centrepiece of this instrument”
The Omni 102 is a fine example of a small to medium refractor, and this became evident when we turned it to a selection of objects in a clear night sky. With its aperture and focal ratio, this telescope is more suited to views of the Solar System and Moon, but it also offers good views of a selection of deep-sky targets. We took advantage of a full Moon. Slotting the supplied 25mm eyepiece – which provides a magnification of 40x – into the 1.25-inch star diagonal, we were soon studying the lunar surface. The lenses are of superb quality; the StarBright XLT coating ensured bright and crystal-clear views as we toured craters and mare. Lunar rilles and mountains were also breathtaking. The Omni 102 drinks in plenty of light, so we recommend investing in a Moon filter for very good, superior contrast.
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: the extra weighting is especially useful for those wishing to try their hand at basic astrophotography.
Sadly, we did notice a degree of false colour
– or chromatic aberration – which gave bright objects a blue-purple colouration. For the cost of the telescope, we did expect to see this through the optical system of the Omni 102, but we were relieved to see that it wasn’t as severe as we had feared. In fact, the chromatic aberration is so minor that we quickly forgot about this minor problem in the telescope’s optical system.
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 -1.46-magnitude star Sirius in Canis Major (the Great Dog). We noted that views were sharp across a good proportion, with only slight trailing off in clarity around the field of view’s edge.
We quickly moved over to gas giant Jupiter and its four largest moons: Ganymede, Io, Callisto and Europa. Overall views were impressive, and we were able to detect the gas giant’s bands with ease, while its satellites appeared as specks of light either side of its brilliant disc.
We did note a halo around Jupiter brought about by the Omni XLT 102’s optical system, which unfortunately didn’t disappear until we fitted a blue filter. However, the planet’s atmosphere stood out beautifully, playing up the cloud belts and the famous Great Red Spot.
With Venus making a dramatic presence 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, but we were able to make out a phase with 60 per cent illumination as well as some atmospheric shading when we made use of a deep-blue filter.
The red giant star Betelgeuse in Orion (the Hunter) kept its stunning orange-red colour at
40x magnification. Meanwhile, the diffuse gas of the Orion Nebula (Messier 42) and its Trapezium Cluster were picked up easily with the additional help of averted vision. Both objects were picked out with impressive contrast and clarity, certainly a highlight of our tour of the night sky.
In terms of optical prowess, we can highly recommend the Omni XLT 102 – especially given the minimal colour fringing when observing bright targets like Jupiter and Venus. Due to its aperture size and focal ratio, this refractor is best suited to Solar System targets as well as fair views of bright nebulae and galaxies.
You don’t get a great deal in the way of eyepieces in the package, but you do get a highquality build for a moderate price – one that will last for many observing sessions to come, while being versatile enough to be accessorised with a full suite of add-ons.
Due to the advanced mount, we wouldn’t recommend the Omni XLT 102 to sky-watchers without prior experience of using a telescope – especially if the astronomer isn’t familiar with setting circles and using right ascension and declination coordinates.
However, for those who feel they can make the most of what the Omni XLT 102 has to offer, it is a great piece of kit for the serious skywatcher and for those looking to try their hand at astrophotography.