REVIEW:
StellarDrive X 6R PRO mount – DarkFrame Optics
First published February 2026
Intro
This review documents my experience with DarkFrame Optics, after sending my Sky-Watcher EQ6-R PRO mount to them for conversion to a StellarDrive X 6R PRO. It focuses on the upgrade process itself, my reasons for choosing this modification, and how the converted mount performs in real-world urban astrophotography use.
DarkFrame Optics
I bought my Sky-Watcher EQ6-R PRO mount back in September 2022. It worked well, and was a good fit for my heavy Askar 130PHQ telescope. I could generally track in the 0.6 – 0.7″ range, and on the best nights it could dip even lower. However, after two and a half years of use, I started to notice the quality of its tracking was going downhill. 0.7″ become a distant memory. Six months later and things went from bad to worse, with guiding spikes so severe and frequent that the mount was essentially unusable. Disaster!
I did some research and discovered this isn’t exactly uncommon. These mounts require maintenance after a while (typically three to five years) for a number of reasons, such as the grease inside them seizing up.
So, what to do? There are plenty of DIY maintenance tutorials online, including for well-regarded Rowan Belt upgrades. However, I’m not mechanically-minded, and the thought of opening the mount up didn’t fill me with confidence.
Then I came across DarkFrame Optics. This is essentially a one-man operation run by David Woods, with admin support from his wife Sharon. Based in the UK, but with customers internationally, David performs maintenance and tuning on a huge range of mounts, with the idea being that they’re returned to owners better than new. Could this be the answer I was looking for?
PRO or ULTRA?
I dived into the DarkFrame Optics website and don’t mind admitting that I was a little overwhelmed with the sheer amount of information on offer. It was a bit difficult to find exactly what I needed; i.e. the options for fixing and tuning my EQ6-R PRO. I emailed DarkFrame Optics, and received a reply from David the next day (even though it was the weekend).
David outlined the best options for me, which boiled down to having the mount essentially rebuilt to become either a StellarDrive X 6R PRO (for £669) or a StellarDrive X 6R ULTRA (for £1199).
- Both have a payload capacity of 25kg (up from a stock EQ6-R PRO’s 18.3kg).
- Both have fluid balance in both axis.
- The sealed OEM axis bearings are replaced with heat-treated open bearings
- Both feature StellarDrive SPX worm gears (the existing gears reprocessed to a sub 7 ArcSecond Periodic error.
- Both feature upgraded drive belts, but the ULTRA upgrade motor pulleys to eliminate and drag on belt sidewalls, while the StellarDrive X version retains the pressed alloy ones.
- Bolts and screws are replaced with A2 Stainless Bolts and screws. The worm gear block are threadlocked to hold backlash.
- Brass gear rings are cleaned and super finished.
- The ULTRA has a honed and polished RA casting treatment, plus lapped and hobbed worms and gears for each axis.
- The PRO is capable of guiding around 0.3”, while ULTRA is expected to be in the 0.16-0.25” range.
I thought carefully about the best option for me. I decided I’d be happy with consistent guiding under 0.4″, as that would be good enough for me to use my data unbinned. Anything better would be nice for sure, but I rather suspected that at this point the turbulent skies above Bristol would be the limiting factor. Shaving an extra ~0.15″ off for an additional £530 seemed a bit extravagant. If I had really crisp skies then I may have gone for the ULTRA, but in the end I opted for the PRO.
Timeline
After making my decision I was sent a PayPal invoice, which included £39 for door-to-door courier delivery. (It would cost more for international customers). I packaged my mount up and 24 hours later, it was on its way. Note that if you don’t have your mount’s original box, DarkFrame can supply one for an extra £10.
So, the mount was shipped to DarkFrame on 15 December 2025. David said he was working over Christmas, and I should expect it back the first week of January. This came and went, but no sign of the mount. Slight stress set in… I sent a message but didn’t receive a reply. Stress levels increased… I had David’s phone number so gave him a call, and was assured that work was progressing. It would be great if DarkFrame had some kind of customer portal system, where you could log in and see what’s happening with your mount. Even if it’s just a sentence or two, to keep you in the loop.
Eventually the mount was delivered back to me on 16 January 2026 — almost exactly a month after it was sent. I guess timings will vary based on how many mounts are being worked on at any given time, so that timeline won’t apply to everyone. I think a month is fine though, considering it included Christmas and New Year.
The mount was packaged well, and came with a certificate from DarkFrame Optics. The exterior of the mount looks essentially identical to before, albeit with lovely new red RA and Dec clutches; and some snazzy StellarDrive logos attached.
I eagerly fastened the mount to my pier, and then attached the telescope. The RA and Dec axis were so fluid, after getting the balance right it was like the telescope was floating.
There was a note in with the mount about letting it run in for as long as possible before use, so I set it tracking a random point during the day, and awaited the first night under the stars…
Initial tests
On the first clear night I had to begin with the less than glamarous task of polar aligning my mount; something I only rarely do, as it’s more-or-less permanently mounted on its pier.
Once that was done I selected a point in the sky, slewed there, and started tracking and guiding. To begin with I decided to try my old guiding set-up, a William Optics 50mm guidescope and ZWO ASI 120MM guidecam. Everything is controlled via an ASIAIR Plus. After running the calibration routine, I sat back and watched the guiding graph. And… was a bit disappointed. The total RMS was generally hovering around 0.7″, but frequently shooting up much higher, well above 1.0″. I tweaked all available settings, but just couldn’t get a satisfactory result.
Frustration building, I decided to ditch the guidescope system entirely. So, off went the guidescope and guidecam, and on went my new Askar M54 OAG and ZWO 220MM guidecam. I rebalanced the whole rig, fine-tuned the OAG focus, and recalibrated the guiding. The results… better, but still not incredible. Total RMS was around 0.7″, as before, but a little more stable. Honestly though, still not up to my expectations.
Then I noticed something: only a single guidestar was selected. I’m used to seeing lots of stars circled in green, so having just a single one was odd. This was a clue, for sure. I went into the guiding settings and increased the guidecam’s gain to High. Suddenly the guidecam could see lots of stars, and multi-star guiding commenced. The improvement was immediate, with guiding in the 0.3″ to 0.4″ range. This was more like it!
I spent some time tweaking the ASIAIR’s guiding settings, and things got even better. At one point the total RMS dipped to 0.22″, which is a personal best. Generally it was between 0.25″ and 0.35″, occasionally spiking a little higher.
I appreciate that for a proper, thorough test, full guiding graphs would be useful. I can’t see how to get these from the ASIAIR, though. I read that you can access them if you hook a laptop up to the ASIAIR, and I tried this, but no joy. The real benefit of long-term graphs is that you can go beyond just using the total RMS as a rather blunt measure of success, but actually see how steady the guiding is over many hours. In lieu of this data, I have to make do with snapshots of the ASIAIR graphs. Hopefully they give a reasonable indication of the mount’s performance. Remember, this is from a Bortle 8 city centre, and it was a fairly windy night:
Entire night test
As soon as the skies properly cleared (more or less!) I put the mount through its paces by imaging M81 and M82 for an entire night.
As mentioned already, I’m not able to save guiding graphs of the entire night, but I did check my ASIAIR’s display periodically. I’d say that the total RMS was between 0.3″ and 0.4″ about 90% of the time. It occasionally went higher, but not beyond 0.6″, and there were no suspicious spikes. High cloud and wind were probably causing some issues, but I can’t say for sure.
Eventually I gathered 105 5-minute subframes, although PixInsight‘s Blink function revealed that passing thick clouds rendered a hefty chunk of that data unusable. 72 subframes (six hours) were unaffected. I think that the mount performed brilliantly when cloud wasn’t a factor; stars were consistent and tight. No dropped subs due to the mount, as far as I could tell. I’d expect around 20% from my stock EQ6-R (although that was with the guidescope rather than OAG). So, very promising!
I found data of the same galaxies I took almost exactly two years ago, using the same Askar 130PHQ telescope, ZWO ASI 2600MC PRO camera, and Optolong L-Quad Enhance filter. I then integrated the best six hours of data and processed this alongside the new StellarDrive data, in the same way, just up to and including stretching, in order to compare. Obviously this isn’t really an apples-to-apples comparison, as the data were collected on different nights.
I’ve made two slider-view comparisons below. Stock EQ6-R PRO is on the left, while StellarDrive is on the right. I think that the StellarDrive looks a little better, but there’s not much in it, and it could be accounted for by local atmospheric conditions. The EQ6-R PRO data was cherry-picked from a much larger pool however; it just couldn’t match the StellarDrive’s fantastic consistency. I suspect that’s where the biggest benefit is.
I then decided to really zoom in on a single star. I’ve had an issue for a while, in that brighter stars look a bit “funky” — like they’ve got little spikes coming out of them. I was worried my telescope might have pinched optics. Another possibility was that the guiding issues in my stock EQ6-R PRO were wobbling things enough to create these aberrations. Below is another slide-comparison, featuring an extreme zoom of a single star exhibiting this behaviour. (Hopefully you can see it on your screen; a computer monitor may show it better than a phone screen). Good news: the effect completely disappears in the StellarDrive view, with the glowing halo looking perfect. This is a big win, and makes me very happy!
Conclusion
I’m really impressed with my StellarDrive X 6R-PRO mount. The very accurate and responsive guiding is attention grabbing for sure, but it’s the fact that it’s so consistent over an entire night that truly makes it a game changer for me. Dramatically cutting down on the number of dropped frames, while simultaneously increasing the quality of the data, means I can obtain long integration times faster, and will have a tangible improvement on the quality of images I produce.
I often say that when planning astro rig upgrades you should consider what will give you the most bang for your buck. £669 for this upgrade is a bargain! It’s worth stressing though that a DarkFrame Optics upgrade needs the basics right in order to work well: your mount needs to be well balanced, polar aligned, and (as I found) be equipped with an appropriate guiding system. I do wish I’d tried my new OAG and guidecam with the stock EQ6-R PRO, as I suspect that would lessen the gap, but I’m still confident that the StellaDrive would be a comprehensive improvement.
It’s a shame that communications with DarkFrame Optics is hit-and-miss. There’s no arguing with the final results though, and I’m definitely a happy customer.
Gallery
Build photos
David kindly provided these photos of my mount during its build process.
All photos courtesy of David Woods / DarkFrame Optics.
Where to buy
Affiliate links from Astroshop.eu and High Point Scientific help support the site at no extra cost to you. I don’t receive any commission from DarkFrame Optics.
Mount: StellarDrive X 6R PRO
Buy EQ6-R PRO from Astroshop.eu
Buy EQ6-R PRO from High Point Scientific
Rebuilt into a StellarDrive X 6R PRO by DarkFrame Optics.
Askar M54 Off-Axis Guider
Read my review
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ZWO ASI 220MM Mini
Read my review
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