If you want to embark on astrophotography, then an equatorial mount isn’t just desirable, it’s essential for any serious astro-imager. Why? As the Earth turns on its axis, the sky above seems to spin, with stars rising in the east and setting in the west. If you point a camera at a certain point in the night sky and leave it on an exposure longer than 30 seconds, you’ll notice that the images of the stars become trailed as they move during the time of the exposure. If your intention is not to take images of star trails (which is an art form in itself) then you need to be able to track the motion of the stars throughout the exposure, so that they appear as sharp points of light, rather than trails. This is where an equatorial mount is crucial.
Why is an equatorial mount essential?
This rotation of the night sky is around an axis centered on the celestial pole. The closest star to this pole is Polaris, the famous Pole Star, and all the stars appear to rotate around this spot. And so, to track the movement of the stars, the telescope mount must also rotate around this point. Making it so that your mount and telescope can do this requires a simple process called polar alignment, but you need an equatorial mount to make it possible. For contrast, alt-azimuth mounts simply move up and down and left and right, rather than following the arc of the stars around the sky, which makes tracking for long exposures impossible.
To polar align, you must first set the tilt of the polar axis to match your latitude. Manual equatorial mounts will feature setting circles that allow you to do this, but with computerized Go-To equatorial mounts you can simply set your location using the database in the hand controller, and following an alignment procedure that targets several bright stars that are then matched to their positions in the database, so the mount knows exactly where its location is. This is particularly handy if you don’t know your latitude! Then, target the Pole Star in the finderscope (you can also invest in a small polarscope that provides more accurate fine-tuning so you are pointed exactly at the celestial pole). Once done, you can rest assured that your equatorial mount is polar aligned, and if you’re imaging using a motorised mount, you can do so safe in the knowledge that your image will feature pinpoint stars, not long star trails.
Of course, there’s more to equatorial mounts than simply polar aligning them. When choosing a mount you want one that tracks smoothly and accurately, with quiet motors so you don’t wake the neighbors, has long battery life on cold nights, can carry all the equipment that you’re going to put on it (telescope, eyepieces, filters, cameras and so on) and which fits with your budget.
So which do you choose? For the uninitiated, there’s a bewildering amount of choice, but here we have selected five that cover a range of requirements and budgets.
Best equatorial mounts in 2022
Sky-Watcher’s EQ5 PRO SynScan equatorial Go-To mount is the perfect example of a great mount that wants to work with you, not against you. Out of the box, the set-up was straightforward, and out under the sky, the polar alignment was wonderfully versatile, with one, two and three-star alignment options.
Why would you need so many alignment options? It all depends on your needs. If you’re just out under the stars for a bit of quick grab-and-go astronomy before it clouds over again, then one-star alignment is sufficient, and we found that under one-star alignment, the Go-To was placing our chosen targets in the centre of the field of view to within an accuracy of about an arc-minute – certainly good enough for a spot of visual observing.
Of course, if you’re planning an all-night session obtaining deep exposures, then you’re going to want to opt for the three-star alignment for maximum accuracy, and we found the tracking to be mostly spot on.
There’s ten different slew speeds to get you around the sky, and to track objects (not everything moves at the rate of stars – the Moon, planets, and some comets will track faster than the background stars). Thankfully the motors are fairly quiet, even at the fastest slewing speed.
Where the mount is limited is in its carrying capacity. Though it’s a stable, chunky build, it’s not a heavyweight mount with a 9.1-kilogram payload capacity. This limits the mount to smaller telescopes, but we were confident with it carrying a 6-inch refractor with room to spare for imaging accessories. It could probably carry a five-inch reflector, but not larger apertures.
We found that, like its little brother the EQ5, Sky-Watcher’s EQ6-R PRO SynScan is a delight to set up and use, capable of carrying a much larger payload and with some nifty extra features thrown in. Its large payload capacity means that it can mount almost any feasible combination of telescope and imaging accessories. Indeed, we can safely say that if you get this mount, then you probably won’t ever need to upgrade to another because it can handle pretty much anything.
Key to its success are two features. One is the inbuilt polarscope, for aligning the mount on the Pole Star, Polaris. Rather than looking through an eyepiece, the view through the polarscope is displayed on the hand controller’s screen. Then you just have to adjust the alt-az bolts to centre Polaris in the field of view – it was dead easy, and didn’t require any further accessories or software. Just be aware the the polarscope has an illuminated reticle, and and we found that you’ll need to turn the illumination down or the view will be obscured by a red glow.
Then there’s the periodic error correction (PEC) facility, which corrects for backlash caused by gaps between the motor gears. PEC ‘trains’ the mount to compensate for the backlash. It’s pretty straightforward, involving slewing to any star near the celestial equator – we selected one of the stars of Orion’s Belt – and then tracking that star using ‘PEC Training Mode’. Subsequently, we found that the PEC was consistently successful in maintaining sub-arcsecond accuracy while tracking deep-sky objects across the sky, allowing us to take longer exposures before any tracking errors could interfere, and rarely were exposures wasted, all in all making for far more efficient data capture.
The CGX is widely hailed as Celestron’s best astrophotography mount, and having given it a spin, we’d have to agree. It succeeds over its predecessors thanks to advances in its mechanics: improved motors facilitate smoother, quieter slewing. Even the tracking capabilities of some heavy duty mounts can become sluggish when a tonne of equipment is mounted on them; not so the CGX, which happily copes with large payloads with all the comfort of a championship weightlifter.
So what, exactly, is so improved? It’s all in the design of the worm drive in the mount’s motor, which is now belt-driven and spring-loaded, leaving out unnecessary gear cogs where gaps in the gear teeth can cause backlash. The mount slews wonderfully smoothly as a result, with nine different slew speeds to choose from. On top of this, there’s Periodic Error Correction, and it all resulted in extremely good performance.
The CGX is a heavy-lifter, designed for large telescope apertures of between 6 and 11 inches – light-buckets for capturing the faintest of galaxies and nebulae. The
equatorial head has a low profile, making the mount more compact and therefore more stable and not prone to wobbling, unlike some larger models. It also features professional-level control software, which Celestron have designed in conjunction with high-end instrument manufacturer, Planewave Instruments. All in all, the CGX oozes high quality, but be prepared to pay a high price for it.
We were pleasantly surprised to find how deceptively tough and sturdy iOptron’s CEM26T mount is. It’s very lightweight and eminently portable, weighing in a less than 5 kilograms – perfect for taking to a remote dark-sky site, or even as part of your luggage on an air flight.
But because the CEM26 is centre-balanced, meaning the weight of the mount and the telescope it is carrying is focused centrally onto the middle of the tripod, it turns out that the CEM26 is one of the most stable mounts you could hope to get, and that means you can add a little more weight to it than you’d otherwise expect without it wobbling about. The specifications suggest that it can carry instruments weighing up to 12kg, which is 2.6 times the mount’s own weight. In our tests, it functioned happily with a five-inch Newtonian reflector mounted atop it.
Its features are quite impressive too, with Periodic Error Correction and a built-in polarscope – the iOptron AccuAlign – plus a huge database of objects on its Go2Nova hand controller, amounting to a whopping 212,000 objects. You’ll never be short of something to look at with the CEM26!
Most of the mounts in this list – Celestron, Sky-Watcher, iOptron – are mass produced, and as always with any product that is churned out, there’ll be some that have been assembled perfectly, and there will be some lemons. The Losmandy GM811G, however is different – it’s hand-tuned in the factory, ensuring that the engineering and resulting performance of every single mount produced is optimized to the max. And as we found out, that makes a heck of a difference, both in terms of the feel of the build quality, and what the mount is like to use.
The Losmandy GM811G is a hybrid of two of their previous mounts, the smaller GM8 model and the weightlifter that is the G11. The GM811G combines the best of both – the relatively lightweight mount of the G8 with the large carrying capacity of the G11. This ratio of weight to carrying capacity is extremely helpful, especially if you have to regularly lug the mount to your favorite dark-sky location of a star party.
The GM811G comes with all the bells and whistles that you’d expect – periodic error correction, huge Go-To database and a hand controller, the Gemini 2, which really deserves a mention here. Unlike most other hand controllers with their five-line LED monochrome screens, the Gemini 2 is furnished with a colour touch-screen, finally bringing hand controllers into the twenty-first century. You can even connect it to your PC using a USB cable, and mate it to your favourite planetarium software.
There’s two options for tripods, either the lightweight (LW) model, or the chunkier heavy duty (HD) version for when you really want to load up the mount. But for carrying a five-inch imaging refractor and associated paraphernalia – CCD, filter-wheel etc – the LW tripod is more than up to the task. The mount smoothly cruises around the sky, somewhat noisily, be we found its GoTo accuracy to be spot on, with minimal backlash. The mount is pricy, but if you want a mount that has received the personal care from someone in the factory rather than just come off a production line, has a high carrying capacity and exceptional tracking, then the GM811G is the one for you.
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