Celestron NexStar 6 SE
David Hinds Ltd. — www.celestron.uk.com
Written: ~5 years ago

When Celestron launched its NexStar Special Edition range, it was perhaps only natural that they should capitalise on the heritage of the legendary orange tube C8 and choose this colour as the striking livery of the new series. The four telescopes in the SE range have apertures of 4-, 5-, 6- and 8-inches, respectively. All are SCTs with the exception of the smallest, which is a Maksutov-Cassegrain. Each instrument comes on a single-arm altazimuth GoTo mount and tripod with a quick release optical tube. Both the 6- and 8-inch SEs use a variant of the more substantial mount that made its debut with the original NexStar 5 back in 1999 and subsequently refined with the 5i and 8i.

First impressions
The NexStar 6 SE arrives at your door in a single substantial box some 80 x 68 x 32cm tipping the scales at around 15kg. Even if you’re new to telescopes you’ll have the instrument up and running in no time thanks to a profusely illustrated 4-page quick start guide. In essence, assembly consists of attaching the mount (with optical tube already attached) to the tripod, fitting the star pointer and installing 8 x AA batteries. If any further technical details need clarification then you can resort to the 52-page reference manual that covers the instrument’s use and maintenance in considerable detail.

At first glance I felt that the supplied tripod was a bit small giving an average eyepiece height of 90cm with the legs retracted, but it is useable this way if you have a squat fishing-type stool or similar. With a total mass of just 14kg (30 lbs), it’s easy for most adults to carry the instrument outside fully assembled — a real plus for the design. Most people will use the 6 SE with the tripod legs fully extended, yielding an average eyepiece height of 135cm. I would recommend removing the rubber tips of the tripod’s rubber feet for use on concrete since they actually exacerbated what little vibration the setup displays. That said, the NexStar 6 SE is a reassuringly solid and stable instrument; even on grass with the legs fully extended, vibrations die down in 2 seconds or less.

NexStar mount
The 6 SE has five alignment modes to suit just about every observing situation. One of Celestron’s great innovations in the field of GoTo technology is undoubtedly the SkyAlign feature. Simplicity itself, one points the telescope at any three readily observable celestial objects (you don’t even have to know their names) whereupon the built-in computer will work out what they are and create a mathematical model of the sky. All the NexStar needs from you is your location, the date and time. With the optional CN-16 GPS accessory, the built-in computer will establish your position and local time for you.

One criticism levelled at some GoTo mounts is the difficulty in establishing a daytime alignment when you can’t see the stars and wish to locate Venus or Jupiter in daylight. This is not a problem for a NexStar SE when Solar System Align is used: just level the tripod, establish your location, date and time, and align on the Moon or the Sun (you have to override the default settings to use the Sun as an alignment object and have an appropriate objective filter). Thereafter, you can GoTo your chosen daytime planet or, indeed, bright stars. The 6 SE will run off its internal 8 x AA batteries, but for prolonged use an external rechargeable battery (such as the Celestron PowerTank) is highly recommended.

In repeated tests conducted during early July 2007 I found that SkyAlign was quick to setup and very reliable, never failing to place a requested object into the field of view of the supplied multicoated 25mm eyepiece at 60x magnification. On one occasion I deliberately tried to fool the system by aligning on stars Arcturus, Altair and Jupiter, thinking that the computer may be confused by the proximity of star Antares to the planet — it wasn’t. The azimuth motor was slightly quieter than the altitude drive when slewing, but not as loud as some competing GoTo scopes. The altitude axis also displayed a bit of mechanical backlash, but the computer more than adequately compensated for it.

Optical tests
Celestron’s decision to move its 5-, 6- and 8-inch Schmidt-Cassegrain optical production from Torrance in California to China initially raised some eyebrows in the industry, but any concerns over optical quality have proved unfounded. Having used four C6 tube assemblies, I can vouch for their consistency good performance with smoothly polished optical surfaces and good spherical correction.

In side-by-side tests with a 6-inch Orion Optics Newtonian equipped with Hilux coatings, I could see little to no difference in light grasp on globular cluster M13 — a fabulous sight in both instruments. Given that the C6 has an extra star diagonal prism in the optical train, the StarBright XLT coatings evidently work very well.

Late into the evening of July 7th 2007, I used the 6 SE to observe Jupiter’s Red Spot close to the planet’s meridian and saw much detail along the border of the North Equatorial Belt and North Tropical Zone in moments of excellent seeing. I also watched the end of a transit of Jupiter’s largest moon, Ganymede, looking like a bright bead in contrast to the dusky limb of its parent planet.

Celestron’s decision to supply the optical tube of the NexStar SE range on a standard Vixen-style dovetail bar was inspired. Not only does it enable you to balance the tube precisely when adding accessories, you may use other tube assemblies (such as a short focal ratio ED refractor) on the same mount. The optical quality of the Chinese-made C6 Schmidt-Cassegrain tube assembly is very good for the price and delivers all one expects of a compact, obstructed optical system. The mount is solidly engineered, eminently portable, and reliably finds objects. The NexStar 6 SE gets a well-deserved thumbs up from me. Highly recommended.