The Celestron Nexstar Evolution 8 Computerised Telescope
The Celestron NexStar Evolution 8 Computerised Cassegrain telescope is a large Schmidt Cassegrain. It’s got a gaping 203.2mm (8″ aperture) and 2032mm focal length. Basically, it’s a bucket full of light. With these specifications, this telescope is capable of reaching high magnifications (480x highest practical magnification according to Celestron) suitable for viewing planets and deep sky objects.
To put this into perspective, in the box, you’ll find two eyepieces: a 40mm for wide field viewing (51x magnification) and a 13mm for closer views (156x magnification). These eyepieces provide a good foundation to explore the night sky. If you want to get the most out of your telescope and push it to its limit, you will want 4.2mm eyepiece, which can be achieved using something like a saxon Cielo 4.5mm eyepiece (you would get a magnification of 451 times). Alternatively, you could get a lower magnification eyepiece and add a barlow, such as a Celestron Omni Series 2x Barlow Lens (not included in the box).
The eyepiece I used for this evaluation was a medium length, at 20mm.
The Celestron Nexstar Evolution 8 Computerised Telescope comes with a single-fork style alt-azimuth mount, which sits on a medium weight tripod. The mount is fully computerised and can be controlled either by the supplied handbox / hand controller, or by a smart device that connects via the mount’s built-in WiFi, using Celestron’s SkyPortal app, available in App Store or Google Play.
The Evolution mount also features a built-in rechargeable lithium-ion battery, which will power the telescope all night. This is recharged using the provided power adapter.
The scope also comes with a red-dot type finderscope, called a StarPointer. The scope I got to test was supplied with a StarPointer Pro, which is similar.
Market placement
Celestron’s Nexstar Evolution series of Cassegrain telescopes is a step up from the Nexstar SE series. The NexStar 8SE has the same 8-inch (200mm) aperture.
In comparison to the SE series, the Evolution series includes WiFi connection to your smart device (IOS and Android), a heavier tripod, and the in-built lithium-ion battery. If you travel to remote locations with your scope, you will find this battery is incredibly useful.
The Celestron NexStar Evolution 8 is the big brother of the Evolution 6, being the same apart from aperture.
If you wanted to spend a bit more, Celestron’s CPC 925 has a bigger aperture again, with a heavier double-fork mount. However, the CPC 925 doesn’t have WiFi built in, and it also needs external power.
There is, in fact, an Evolution 925, which is similar again, although we would consider for the heavier tube that a double-fork mount of the CPC would give more stability and robustness.
| CELESTRON NEXSTAR SE SERIES | CELESTRON NEXSTAR EVOLUTION SERIES | CELESTRON CPC SERIES |
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Purpose and intended ability
Cassegrain telescopes have long focal lengths, which means they are really good at magnifying images. The downside of this is that the images tend to be dim. This means that the Celestron NexStar Evolution 8 is a specialist at small bright things, like planets. If a planet is what you’re after, a Cassegrain is your first choice. For the same reason, the Celestron NexStar Evolution 8 is also really good at lunar close-ups.
To give you an idea of the abilities (and limitations) of the Celestron NexStar Evolution 8, I recommend the useful BBC Sky at Night Field of View Calculator website. This site indicates that with the supplied 10mm eyepiece, the Moon will be about twice the size of the scope’s field of vision. Alternatively, Saturn will be small in the field, but its rings will be clearly recognisable.
The verdict
A pleasant surprise
The Celestron NexStar Evolution 8 is not traditionally a beginner’s telescope, depending on your budget. It’s an impressive unit in all sorts of ways. It’s big, it’s powerful, it’s easy to use, and it’s smart.
First, it’s a pretty large telescope. If it’s sitting on its tripod in the corner of your lounge, it will dominate the room. For those who like to have their scope as a talking point, this one does the job.
Second, it’s got a long focal length, which is typical of the Schmidt-Cassegrain configuration. The Evolution 8′ focal length is 2032, which is frighteningly large compared to my wide-field refractor’s 560mm. That gives you, for the same eyepiece, a very large amount of magnification, but I found that the stars looked pretty crisp across the whole field. This shows that the optics are a very high quality.
The market placement of the Celestron NexStar Evolution 8 certainly doesn’t make it a starter scope, but I found it surprisingly easy to use, despite its premium price point and capabilities. My rig is a refractor, and it sits atop an autoguided NEQ6 equatorial mount that demands exquisitely precise polar alignment. I describe it as like driving an MG – beautiful, when it works. In contrast, a total beginner could use the Celestron NexStar Evolution 8.
What’s more, before I got to evaluate this scope, my only deep experience with a Cassegrain was a Meade LX6. This is a lot smaller than the Celestron NexStar Evolution 8, and the telescope’s mount gave me quite a few problems with software and set-up. Eventually, I have to say, Meade and I solved the problems and it became a useful scope.
These experiences had given me the impression that if you want a high-end outcome, you need to put in heaps of effort. But I was wrong. I was able to put it together quickly, the Celestron SkyPortal iPhone app worked, the alignment took only a few minutes, and I was off and observing.
Ease of use
While there’s obviously going to be a learning curve, this thing is not difficult to use. You don’t need to know the stars, it’s easy to align, and you don’t need to be muscle-bound. You don’t even need to know what you want to see – the scope will take you on a tour!
It’s a go-to
The biggest development in amateur astronomy in the past few decades has been the go-to mount. This really has revolutionised back-yard observation. Previously, to find things you had to use a paper map and “star hop” from a bright star to dim star, to dimmer star, before eventually finding the right spot. It took ages, and more often then not you’d get lost and have to start again. Believe me, it’s tedious. These days, all you have to do is ask the Celestron NexStar Evolution 8 to show you something and it moves right there itself.
Star alignment
The Evolution series is on an alt-az mount (as against an equatorial mount), which is perfect for visual observers. It’s much easier to use and quicker to set up, and you don’t need to do that horrible polar alignment stuff.
All go-to computerised telescopes from all brands need “star alignment” before an observation session. This is different to a polar alignment, and tells the Celestron NexStar Evolution 8 where the stars are. You’ll need to go through this procedure (unless you’ve optioned it up with a StarSense auto-aligner) and you’ll have to help it along – a bit.
The pleasant surprise, though, is the Celestron star alignment is excellent. You just slew to any three bright stars, make sure they’re in the centre of the eyepiece field and press “align”. That’s right – you don’t need to know the names of the stars. The Celestron software is clever enough to determine from here where the stars in the sky are. In this, the Celestron software is ahead of its rival, the SynScan technology, which nominates stars it wants you to slew to.
I’ll write a separate blog on how to align a Celestron NexStar. When I do that, I’ll put in a link here.
Weight and portability
The Celestron NexStar Evolution 8 separates into three basic units, the tripod, the mount and the telescope itself (there’s a picture of these main bits above).
Again, my experiences with my NEQ6 prejudiced me, so I was expecting some heavy lifting. But none of these parts are too heavy to lift.
The heaviest part is the mount. Celestron has really improved the ergonomics here, and put handles on the fork (that’s the upright bit) and the tray.
The tube isn’t terribly heavy either, but it really could do with handles somewhere, like on the newer C8 tubes. Attaching the tube to the mount when the mount is up on the tripod can be awkward, especially if the the tube has a finderscope. There’s nowhere to securely hold the tube, and you end up cradling it like a baby. It’s really something you wouldn’t want to drop!
The Celestron NexStar Evolution 8 isn’t so large that it’s hard to move around. I drive a small car (a VW Polo) and the tube fits easily into the cabin (I put it on a seat with a seatbelt around it). I put the tripod legs on the floor behind the driver’s seat, and chucked the mount into the boot. It’s certainly more portable than my refractor and its NEQ6 mount and tripod legs.
The other good thing about it being not-too-heavy is that you can move it around your back yard if what you’re looking at wanders behind a tree. Of course, moving the scope will confuse the mount, and so you have to disconnect and re-align when you do this. Compare this to my big heavy NEQ6 with its refractor, cameras, autoguider, autofocus and counterweights – once it’s down it ain’t moving.
Optics
I found the optics of the Nexstar Evolution 8 to be very good indeed. Light gathering is excellent (as you’d expect from an 8-inch aperture), and the Evolution series’ StarBright XLT coatings give it an added level of quality over the SE series.
I took the scope out to the dark sky site in January, so there were a few objects in the north east available for me to look at. Unfortunately the “seeing” was poor, as it had been a hot day and the atmosphere was very unstable. The Moon was just past full, meaning I had a couple of hours of viewing before it rose and blotted out much of what I was looking at.
Visual work
Through the scope, the Pleiades were larger than the field of vision (I was using a 25mm eyepiece and didn’t have a 40mm). The stars were clear, and the view was nice and contrasty, indicating little dispersion of light. At the edges, I couldn’t detect any coma or colour fringing, indicating high-quality optics. I didn’t see any nebulosity around the stars, but you’d probably have to have a much larger aperture to see that.
When I looked at the Orion Nebula I was in for a treat. The nebula was large, as bright as you would expect for a full moon, and I could see a lot of detail. The magnification of the Nexstar Evolution 8 is such that you can easily see all four stars of the quadrilateral at the core of the nebula well separated. This is a good test of a scope, and one which Nexstar Evolution 8 passed easily.
Finally, and with a little apprehension, I slewed the scope at the Moon. I’d never looked at the Moon through an 8-inch instrument before and I didn’t have a filter. Ouch. It was as bright as I’d expected, but very clear and contrasty. I was mostly trying to photograph the Moon (see below), and really hadn’t expected to look at it. The scope has so much light gathering that I was actually able to see a well-focused image of the Moon on my hand. The scope was acting like a projector, showing craters on my palm.
DSLR photography
After looking through the telescope for a while I attached a DSLR. I have a Pentax K3-II, but Nikon and Canon (and other DSLRs) attach in the same way. Celestron also sell a t-adapter for the telescope tube, which can be used to connect your DSLR to your telescope. This screws on to the rear of the tube, replacing the visual back, diagonal and eyepiece. The t-ring for the DSLR screws to the adapter and the DSLR clips onto the t-ring just like any other camera lens.
Using my DSLR without any lens apart from the scope itself, I found that I wasn’t able to get the whole of the moon into one shot.
If I wanted to get a photo of the whole Moon I would have had to take four images, and stitch them together afterwards (I use Microsoft ICE, which is free).
Next, I had a rough go at M42, the Great Nebula in Orion. It’s a favourite test subject at this time of year. I took 100 exposures of 5 seconds each and ISO 1600, and stacked them (without calibration shots) in Deep Sky Stacker. More time on finessing both the original photo (fiddling with exposures, tracking, etc.) would improve this, as would more time with post-processing (with better calibration, etc.). But this gives you an idea as to what the telescope is capable of.
CCD photography
The last thing I wanted to test on this telescope is how well it worked with an astronomical sensor. The one I was using was the Orion Starshoot 5MP, which connects through a USB cable to a laptop. The Starshoot 5MP has a small sensor, making it useful for very small targets such as planets.
To photograph the Moon, I recorded a movie through the scope. This gave me about 1000 frames at 640×480 resolution. I processed the images using PIPP and then Registax and produced this. Visual observation was poor on the night due to the the in the atmosphere and I was surprised that I got this.
Later in the evening (at about 4am) Jupiter rose. This gave me only a short time before the sun rose. I used the same technique that I’d used for the Moon, and got this small image. It’s not a great photo, but this does not reflect on the scope, but rather the poor seeing conditions at the time. If nothing else, it highlights how small and bright planets are!
In order to get a larger image, I would need some additional magnification. This could include a Barlow or an eyepiece projection system. It gives me something to aim for.
Mount
The combination mount and tripod is a good enough size. It’d be perfect for the smaller Evolution 6. If it were smaller and it might not be stable enough for the larger Evolution 8. This is the reason why I wouldn’t recommend Celestron’s Evolution 925, it’s probably too large for the supplied mount.
The mount is heavy and stable enough with the Evolution 8. It withstood a bump without having to re-aim the telescope. In my case, there were two specific bumps. The clumsy nose collision against the eyepiece was a normal thing. The Labrador tail collision with a tripod leg was a little more unusual. (I never thought I’d end up writing that in my career, but our dog is very waggy.)
The tripod legs, like all I’ve come across, have points on the ends. These sunk into my garden a little unevenly, stuffing up the level. I have three bricks set into my lawn for my own scope, and I was able to adjust the tripod so that it used these. I think supplying some sort of pad, like vibration suppression pads, would help here.
Another thing that would improve the tripod legs would be double locking screws for the extensions. It wasn’t long ago that I saw the aftermath of a leg extension screw failing. It wasn’t pretty.
Clearance
The larger Celestron alt-az setups have always had a problem with clearance. Just with the diagonal and an eyepiece, I can look an a target at zenith. I can even do it with a DSLR on the visual back. However, with the tube balanced correctly, the front of the tube has to be a long way forward. This means it crashes into the tray when pointing downwards. Clearly you’re not going to be observing anything below the horizon. However, my experience with the Meade gave me a habit of parking a Cassegrain scope objective-down.
Software and control
You can control the scope in two ways. You can use the handbox that is supplied with the scope, or the Celestron SkyPortal iPhone app. I didn’t get to play with the handbox, so this is going to be all about the app.
I do like the Celestron SkyPortal iPhone app. As I mentioned above, you don’t need to know the names of stars you’re going to align on. This is a big advantage over its major competitor, SynScan. The SkyPortal app also shows a map of the stars. You can slew from this user interface by touching a star or planet and touch “goto”. Again, with SynScan, you need to select your target by name. If you see a star you want to point the telescope at, but don’t know its name, it can get complicated. This is even more complicated if there’s another star not far from your target. To be fair, the SynScan can get around this, but that’s a different blog…
When I slewed to a target using the go-to function, the telescope moved reasonably accurately. By that, I mean it put my targets into the eyepiece. While I didn’t use the feature, you can add alignments to make slewing even more accurate.
The iPhone app provides four slewing rates so you can move the scope around. I didn’t find I needed the slowest rate. This is the rate that might be used for really fine adjustments. These are useful when you’re touring the Moon or locking onto Saturn with the highest magnification. The fastest slewing rate took maybe 30 seconds to move the scope all the way around. While I’m patient enough, if you’ve got a child with you, it might be a bit long.
The app (like all of them) has a “night” setting that turns the screen monochrome red. This prevents the phone screen from dazzling you. However, even with the red screen, I did find it was difficult to slew the mount to centre the stars. I found I had to look away from the eyepiece to figure out which button to touch. I don’t know about programming phone apps, but a swipe might be more convenient. This would allow you to hold your finger on the phone while looking into the eyepiece. Sliding your finger around could adjust the mount without having to find different buttons.
One minor irritation about the SkyPortal app is its US centricity. Every photo (but one) in the app I found was somehow to do with the USA. Either it was the Earth – with North America prominent, or was of a feature within the USA. The exception was a photo of Mount Everest. Not a serious gripe, of course, but there are other countries in the world, you know.
Backlash in slewing
Backlash in slewing was a bit of an irritation. All mounts have backlash, or the gears would grind and seize. When I slewed to the left or right, there was quite a delay before I saw any movement in the eyepiece. The delay was only a few seconds, but I thought the clutch must have been unlocked.
The Celestron NexStar Evolution 8 app has a setting for backlash compensation for both axes. I didn’t look into these, and so I can’t describe how it works or hoe effective it is. I’ll leave it to telescope owners to investigate this themselves.
Tracking
The mount I evaluated didn’t have perfect tracking. As a test, I took a series of 10 second exposures on the Orion Nebula. These showed how the scope tracked over about 45 minutes. The time-lapse is on the Optics Central YouTube channel.
At the start, the quadrilateral in the Nebula started in the middle of the field. But at the end of the time-lapse, it’d wandered off to the left and had nearly left the frame. You might be able to adjust it in one of the advanced settings, but the rate the mount came with wasn’t fast enough.
Clearly an autoguider (such as the Celestron Nexguide, possibly the Sky-Watcher Synguider, or another autoguiding system) will solve this problem. At extra expense, of course. Look, if it takes that long for your target to drift away, it’s not a huge problem.
Apart from tracking errors, the alt-az mount makes the scope unsuitable for long-period astrophotography. Exposures of 20 minutes would suffer badly from field rotation. If you want to take astrophotographs, this is not the mount for you. Rather than the NexStar mounts, I’d be recommending an equatorial mount such as the Celestron Advanced VX for long-exposure astrophotography.
Bill is Optics Central’s expert on astrophotography, telescopes and bird watching. You’ll find him in the Mitcham store on Fridays and Saturdays. Come in for advice on how to get the best out of your current telescope, what your next telescope should be, how to take photos of the sky, or even how to see some rare birds.
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Thanks. good review.
Use to own a se4. Like to look of this unit Evolution8.
I’m in WA. Any suggestions on the best place to purchase, as most of the suppliers are over Eastern Aus.
Thank you.
Mike