I love a factory-fresh unboxing! SCT optical configuration, from celestron. However, that compactness requires steeply curved optical surfaces — the primary mirror is F2 - which can be hard to make well and close tolerances are required if performance is to be good. Another disadvantage of the design is the large central obstruction. A large obstruction does reduce contrast, but the main effect in my experience is to worsen performance in poor seeing. That means the potential for striae and inhomogeneities varying from sample to sample.
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The Celestron C8 Schmidt-Cassegrain falls into that category. First introduced in , this instrument packed a good-sized aperture into a compact size at an affordable price — and it had a distinctive orange optical tube assembly that made it stand out.
Advertisement The original C8 came with a fork mount on an equatorial wedge with a basic drive for tracking, all mounted on a tripod. In , Celestron changed the tube colour to black. Further improvements were made through the s. In , the distinctive orange colour was reintroduced with the NexStar altaz series. Today, Celestron offers a choice of optical tube assemblies and mounts, including the NexStar range — a good cross between the old and new designs.
All of this fits into a compact orange tube that weighs 11kg and is just mm long. A StarPointer red-dot finder, E-Lux 25mm, 1. The mount is a single-arm, all-in-one unit with the neatly integrated NexStar hand controller, which can be pulled out when in use. There is a power connector and switch on the outside base of the arm, and a battery compartment for eight AA batteries on the top of the base, along with autoguider and aux ports.
A sturdy, adjustable tripod and a software CD are also included in the price. Our Go-To and tracking tests gave good results, with our chosen object almost always placed close to the centre of the view regardless of the alignment routine we used. We were also able to track objects and keep them centred for at least 30 minutes, which was plenty long enough to explore them. After attaching our iPad using the supplied cable and our own adaptor, we were also able to use a sky app to move the scope to objects in its database.
Optically, we were impressed with the results when using the supplied 25mm eyepiece. To test the resolution, we added our own 5x Powermate to the 25mm eyepiece, giving x magnification, and sought out Porrima in Virgo, easily splitting the 1. We were also able to cleanly split 20 Draconis, its two 7th-magnitude stars separated by just 1. Deep-sky views through the NexStar were equally rewarding. The open star cluster M11 in Scutum appeared as a splash of stars in the 25mm eyepiece and we were able to resolve stars in the core of globular cluster M13 in Hercules.
Turning to nebulae, M17 in Sagittarius showed a wonderful glow shaped like a tick mark, while M27 in Vulpecula displayed a good shape. M82 appeared as a large thin strip of disturbed light, hinting at the turmoil within that galaxy. The planets were not ideally placed at the time of our review, but we did manage to make out Syrtis Major and a polar cap on Mars, despite the small size of its disc. Saturn, however, was simply gorgeous. The pale yellow and cream hues of the planet showed up its north belt and north polar haze, while the rings, clearly split by the Cassini Division, were a delight.
This produced a respectable image for our efforts. We can see it being a solid performer for many more years to come. Stars were sharp across 85 per cent of the view and even very close faint double stars could be split using high magnification. Single arm mount The mount is sturdy in construction and carries the optical tube on a Vixen-style dovetail arrangement.
Go-To controller The NexStar computerised hand controller has been designed to slot into the single arm and provides a database of 40, objects to choose from. It was easy to use and the star alignments worked well every time, placing the desired objects within the inner half of the view.
Tripod The sturdy tripod easily holds the weight of the mount and the optical tube assembly. It can be extended to give more height for a better viewing position and, once levelled, provides the perfect platform for the rest of the telescope. The mechanism is smooth in operation and has plenty of focus range to accommodate DSLRs, diagonals and eyepieces.
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Celestron C8 XLT OTA
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Celestron C8 Manuals & User Guides