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Sky-Watcher Equinox-66 PRO

Sky-Watcher Equinox-66 PRO

In my time as an astronomer I’ve been fortunate to tour some of the world’s most majestic night skies, from remote, southern deserts to mountain tops thousands of feet above sea level, and wherever I could I brought with me a small telescope. It’s always moved me in a certain way to see just how much more can be experienced with even the smallest rich field refractor over the unaided eye alone, and in many ways small telescopes continue to be my weapons of choice in the hobby. The technology in amateur instruments today is so good that a compact, lightweight refractor can delivery stunningly high-contrast images, and overstep its perceived aperture limitations to bring out faint objects and planetary features alike. But light is a cruel mistress, and shorter, faster optical systems are relatively more prone to aberrations, which creep in and spoil the image. Enter the ED refractor – a species incorporating exotic glass types and high-precision figuring to outpace aberrations without resorting to longer focal lengths. With the right execution, these can make for exceptional portable instruments. Should Sky-Watcher’s Equinox-66 PRO be counted among them?

The Equinox-66 PRO is easily one of the very cutest telescopes I’ve ever used. To call it small is an understatement – it’s downright tiny! From end to end with the lens shade retracted, it measures a mere 305mm, with plenty of focuser travel to make up the necessary backfocus for its 400mm focal length. Though small in size, the unit feels very well made, and substantial at almost 2kg. It is however shipped in a hard case (not pictured), which although nicely padded, is just too large in my opinion. Yes, it’ll carry your accessories and provide ample protection for the telescope, but if you’re buying for genuine portability, you’ll quickly be hunting around for a smaller padded bag. Fortunately this won’t be hard to find, as the whole ‘scope is no larger than many telephoto lenses, for which there are some fine pouches available. The tube is finished in a sleek, glossy black with chrome trim, and it looks fantastic. Just be warned that it will become a museum of fingerprints if not frequently cleaned, but hey, that’s what cloudy nights are for!

Sky-Watcher Equinox-66 PRO

Mounting is a breeze, thanks to the stock Vixen-style ‘foot’ attached just ahead of the focuser assembly. It features two ¼”-20 threaded holes for perching on a camera tripod, and is well situated for proper balance in a dovetail saddle provided your eyepieces aren’t too heavy. In practise, I found a Tele Vue Nagler Type 6 to be acceptable with a 1.25” diagonal, but the heavier Panoptic 22mm tipped it tail down on a lightweight alt-az mount. The Ethos SX 3.7mm was out of the question! So I preferred a sturdy camera tripod – even the lack of precise slow motion controls wasn’t an issue, as the Equinox-66 performs best at low to medium powers.

The retractable lens shade only adds to the portability of this design, and extends smoothly, holding itself in place even when pointed to the zenith. It’s hard to fault the front end at all, but I did run into trouble at the middle of the tube, where the focuser assembly as attached. A fully rotatable unit, it works (as many others do) by clasping a flange on the tube. Usually, a focuser can be locked in position using a thumb screw, but Sky-Watcher have opted for a bizarre knurled locking ring. It’s big, clumsy, far from smooth, and feels completely inconsistent with the otherwise excellent mechanical quality of the telescope.

Sky-Watcher Equinox-66 PRO

Fortunately, the focuser itself is much better. Smooth and solid, it has about 61mm of travel with no flop or backlash, and is certainly one of the best examples of production line Crayford focusers on the market today. The two speed reduction gear is excellent, a brake screw is included, and the whole thing will support substantial weight without slipping. Slightly unusual is the SCT threaded 1.25” clamp on the end, which you can remove to attach a flattener or 2” SCT diagonal. It’s a nice touch for what might otherwise be a frustratingly restrictive focuser.

So what of the optics? Well, to call the Equinox-66 an apochromat (as Sky-Watcher do) just isn’t quite right, unless one stretches the definition quite a bit. To call it a semi-apo is fairer. The beautifully coated F/6 doublet is a sound performer, and I’d go as far as to say it beats every production line 70mm F/10+ achromat I’ve ever used. That’s saying something, because the Equinox-66 is a tiny telescope by comparison, but whilst there is no universally accepted definition of apochromatism, most agree on a standard that this telescopes doesn’t meet. The phrase “ED” (extra-low dispersion) is most appropriate, as it provides superior image clarity and colour correction partly by incorporating an ED element made from Ohara FPL-51 glass.

I was favoured with some very good nights to thoroughly test the Equinox-66 on two occasions this year. Lately, Taurus (including Jupiter) has been nice and high around midnight, and back in the spring I spent a week using the ‘scope on Mars. Whether on star clusters, doubles, planets or the Moon, the Equinox-66 has impressed me with its level of contrast, saturation and colour correction. Bright objects show no more fringing than a well corrected F/12 achromat, and point sources appear… well, point-like, as they should! Large clusters are aided by the deep constrast of the lens, and appear to satisfyingly leap from the velvet backdrop of space. Planetary images are also a treat, when the aperture is taken into consideration. I discovered a wealth of detail on Jupiter with crisp views up to about 150x magnification, and enjoyed tracking the Great Red Spot with relative ease, despite it being somewhat pale at the time of the test. My evenings with Mars were perhaps more surprising though, as at 160x I was treated to more surface detail than I expected, and very plainly visible polar caps. Altogether, I judged the in-focus images to be excellent, and the range of views available –  from rich ‘binocular-like’ fields to detailed views of the major planets – renders the Equinox-66 a potent little instrument.

Sky-Watcher Equinox-66 PRO

The critical, controlled star test was not quite so complimentary. At 160x (61x per inch) I was reminded of the still present false colour, and I should note for hardcore optics fanatics that the lens is – not severely, but still rather evidently – undercorrected for spherical aberration. This is undoubtedly removing something from the performance of the Equinox-66, but high-quality coatings and a nicely baffled tube (pictured because it’s rarely highlighted) nevertheless result in an extremely compact telescope that punches above its weight. It would make an outstanding guidescope or finder, but holds its own as a travel-ready refractor. At its price-point, it’s a worthy competitor, and deserves a look the next time you’re planning a holiday.