Data Updated: 25 Oct 2017
If you want to know how good our mounts are compared to everybody else's you've come to the right place. I try to update at least once or twice a month, to refine the data and add to it. This is independent data unless specified. You can do your own research, but none of this is skewed.
Not just hypertuned mounts (as no other tuner seems to publish any data for comparison to stock mount on this scale...), but ALL equatorial mounts and compare them online. It makes it easier when making decisions about which one to buy, or whether to tune your mount. Is it that easy? Of course not, this is Astronomy! I have included the native periodic error too, as this is causing the most consternation amongst some owners. The claim is that this figure is the true mark of the potential of a mount from a quality perspective in terms of build and assembly, and that less mounts don't make the grade. Most people guide though with these mounts though. Top of the tree are the Paramounts with 7 arc-seconds RMS (±3.8 arcsec) across their range, although our StellarDrive 6's exceed this...
Now let us manage a little expectation here and a disclaimer. Pretty much any well set up EQ mount that can guide via an ST4 port 'should' guide when properly set up down to circa 2-3 arcseconds, which discussed elsewhere is enough for longer exposures under UK skies. Well, under any skies actually. Oh, it needs to do it with your telescope of choice, DLSR or CCD, guidescope and guide camera. This is where it gets a bit fuzzy but I'll simplify where I can. Primarily, it's all about how it's assembled and designed. With guiding, some mounts are more equal than others. Yes, you should also get what you pay for.
All the information supplied is independent, real-world data unless stated. Your mileage will vary. But before you beat up on your dealer/manufacturer for supplying a lemon of a mount, and it is statistically likely it won't be, it's down to you to demonstrate it as fact. So, if your mount doesn't do as stated, check your set up first. On a good night, it should be in the realm of what you see in the tables. If it's 0.3 of an arc-second or so off, that isn't the time to launch off with a flurry of forum posts or lawyers letters to fix it. If you're guiding or just tracking within or under your limits of seeing, then you are doing really good. Everything comes into play, for long exposure - Polar Alignment, Balance, Guide setup, backlash even voltage! That's 13.8v/3 amps dedicated power supply for you EQ6'ers by the way, not a laptop adapter...
The common rule of thumb is to take off 1/2 to a 1/3 of the stated maximum payload of the mount, if you're astro-imaging. S'not fair you cry! But it makes sense. Sort of. This applies to any worm-driven EQ mount, and should typically be set up slightly east-heavy to provide the mount with an attitude of a controlled fall, so that the RA motor is dictating that precise movement. Your guider by looking at a star dictates sidereal movement, that your motor corrects to. Our tuned mounts can run at full payload and still be sub-arcsecond. It really is down to the build in all cases.
Have a read of this data table: http://lambermont.dyndns.org/astro/pe.html
This list which has been around for awhile lists over 120 mounts stated and independently quoted via owners and forums. It's not quite up to date but illustrates cost in Euros, Payload (max), Period Error (PE) and after PEC training or other control. There's no quoted guide performance here as it doesn't account for that, but useful none the less. If you mount isn't in the tables below then try here.
So why is guiding such a mixed bag? Guiding is needed for exposures longer than 60 sec and EQ mount with a lens or telescope over 400mm focal length. The best I got unguided was 8 mins unguided at 320mm fl lens and Canon EOS450D on a Sky-Watcher Star Adventurer, and also using an AstroTrac TT320X-AG. However, that's because it's light and my Polar Alignment was god-like (it normally is, but I also have to work on my modesty), after 15 minutes of tweaking. Start using a small 70mm refractor even at f4.8, or a 150mm f5 Newtonian and it will start to fall apart quite quickly. Auto-guide and your exposures are transformed from 1 minute to 5, 10 or even 20 minute exposures. As you do this your signal to noise ratio drops, and you are rewarded with more detail and resolution as you gather more of those much travelled photons. However, weather dictates all. Seeing is the speed limiter on this visual highway.
But your mount is now having to work harder when guiding. Remember all mounts should be able to guide down to 2 arcsecs? Heck, even a well sorted EQ5 will guide down to 1.4 arcsec RMS with a lot of practice and fettling, https://stargazerslounge.com/topic/243782-expectations-with-guiding/ ) so what's the deal with these more expensive mounts?
Short answer: Payload and Focal Length vs Exposure.
If you read the above thread then 10 minutes means that you can guide forever? Well, your skies will ultimately dictate that, but your mount has to track the sky, not for 10 minutes but for a few hours if you want to gather enough meaningful image data to create those amazing images. 4 Hours is usually what most pro-imagers say is the minimum. That's where reliability comes in and the closer you get to the limit, then the less more critical your balancing will need to be as your telescope changes orientation. We load test our tuned mounts to ensure that the mount is operating to how you use it. It means the performance will be consistent as you will be guiding for longer. Every time you use it.
The venerable HEQ5 and NEQ6 are seen as the benchmark EQ mounts upon which all others are judged. As well as our reference mounts our customers send us regular data, so not is this only independent, they paid to find out how good their mounts are improved, and they usually had data before and after so here it is as an average in a table.
The PE Factory/guided values are out-of-the-box as independently published on the Internet and customer supplied. The first figure is the peak-to-peak unguided figures for the respective mounts, the second under PHD2, then the third is the overall RMS. Home Modded, is usually owner modified mounts, run via PHD2. DarkFrame tuned data are either our own or customer Reference mounts. We have verifying RA values further, as we have acquired a Telescope Drive Master system and a range of adapter to test and tune various mounts, using PecPrep, to see what's going on under the hood. This system can reduce the PE (in RA only) down to just 1.4 RMS arcseconds on an EQ6. Mounts like Avalon, Paramount and 10Micron (Table 3) are by their nature a better engineered platform with unguided periodic error figures typically into single figures that may match a TDM, for the ultimate unguided performance?
How do I makes sense of all this data?
Some mounts are more equal than others. So think of it like a racing car, where 1/100th of a second determine Pole Position and second place. The simplest example is how we evolved our EQ6 mounts. They've gone down from tracking 0.42 Arcseconds (HEQ5) to just 0.16 Arcseconds RMS (NEQ6) in our latest StellarDrive build. Doesn't sound much but it equates to 72% more accurate guided tracking. Remember, you're tracking a star light years away so the movement is so tiny you can barely see it, less than the twinkling of a star in fact. That's more than double the performance of our previous EQ6 rebuild. So at this level, reliable consistent and accurate tracking is all both guided and unguided. It's how easy you can access that performance consistently which is just as important.
Image: Cropped Single Frame 72mm WO Megrez 72+0.8xFRIII (537mm focal length) modded EOS450D ISO100 3600secs on DarkFrame Hypertuned HEQ5 guided with QHY5L-II mono with 50mm WO Guide scope. On Dual bar with WO ZS71/EOS40D Guided Payload 9KG ©2016 David Woods/DarkFrame Ltd
Table 1 (25/10/17) EQ Sky-watcher - Arc-second Unguided/Guided Performance over 300 second exposures
|Sky-watcher Mount||Payload Kg||±PE Factory||±PE Home Modded||±PE DarkFrame Tuned**||Tested Payload Kg||@Focal length|
|AZ EQ6 GT||20/18*||20-30/2**||28/0.8**||7/2.0/0.3^^||20.3||2000mm|
Key: *Recommended Imaging Payload **Avg Guided RMS (Customer supplied- StellarDrive) @Focal length (tested OTA's on reference mounts/customer data) *** Build Type: 6.5.5 (Flat Earth) ^^ Build Type: 6.3.x (Bonneville)
Table 1.1 (12/04/17) Maximum guided exposure time vs dropped frames (4 hour session @900sec)
|Sky-watcher Mount||Payload Kg||Dropped Frames**||Max Exp**||DarkFrame Dropped Frames**||Max Exp**||@Focal length|
|Star Adventurer||5+3||25-70%* (@4kg)||120 sec||Unguided<10% <5% (guided only)***||900 sec***||537mm|
|EQ5||9/6*||30-60%**||600 sec||Unguided<10% <5% (guided only)**||900 sec||500mm|
|HEQ5||18/12*||10-40%**||900 sec||5-10% (Gen1) 0% (Gen2)||3600 sec***||537mm|
|(n)EQ6||25/18*||10-20%**||1200 sec||<5% (Gen0) 0% (Gen2)||3600 sec***||2000mm|
|AZ EQ6 GT||25/18*||10-20%**||1200 sec||<5% (Gen0) 0% (Gen2)||2700 sec***||3200mm|
|EQ8||25/18*||5-10%**||1800 sec||>1%||1800 sec||1600mm|
Key: *Recommended Imaging Payload **Avg Customer Data ***tested OTA's on Reference Mounts to BT v6.3.x
Table 2: (20/04/2017) EQ iOptron - Arc-second Unguided/Guided Performance over 300 second exposures
|iOptron EQ Mounts||Payload Kg||Factory ±PE||Owner/Tested**||DarkFrame Tuned||Test Payload||@Focal Length||Max Exp|
|CEM60||30||4-6/>1||tba||In Development||18**||2000mm||1800 sec|
Key: **Avg Guided RMS (Customer supplied) @Focal length (tested OTA's on reference mounts/customer data)
Table 2.1 (20/04/2017 EQ Celestron Arc-second - Unguided/Guided Performance over 300 second exposures
|Celestron EQ Mounts||Payload Kg||Factory ±PE||Owner/Tested**||DarkFrame Tuned||Test Payload||@Focal Length||Max Exp|
|AVX||15||15/>2||tba||In Testing||11**||500mm||600 sec|
|CGem||22||15/>2||tba||In Testing||14**||1000mm||600 sec|
|CGem DX||22||15/>2||tba||In Testing||16**||1000mm||900 sec|
|CGE Pro||25||30/>2||no data||In Testing||15**||1000mm||600 sec|
Key: **Avg Guided RMS (Customer supplied) @Focal length (tested OTA's on reference mounts/customer data)
Table 2.2 (29/10/2016) EQ Capable Meade mounts - Arc-second Unguided/Guided Performance over 300 second exposures
|Meade EQ Mounts||Payload Kg||Factory ±PE||Owner/Tested**||Test Payload||@Focal Length||Max Exp|
|LX850||40||--||--||--||2845mm (14")||900 secs|
Key: *With EQ Wedge **Avg Guided RMS (Customer supplied) @Focal length (tested OTA's on customer data) More data please!!!
Table 3 (25/10/2017) Higher end EQ mounts Arc-second Unguided/Guided PE Performance
|Manufacturer||±Native PE (peak2peak)*||PEC^||Guide PE Peak*||Guided RMS**||Max Payload||Cost|
|Pierro Astro EVO6||8||1.6||2.2*||0.6*||20kg||£2250|
|Celestron CGX-L||5-10 (mfrs*)||tba||tba||tba||34kg||$3650|
|Celestron CGX||5-10 (mfrs*)||tba||1.5*||0.25*||25kg||£2350|
|iOptron CEM60||4-6* (mfrs*)||tba||2.0*||0.42*||30kg||£2300|
|Takahashi EM200 Tekka II||7||1.4||3.2*||0.25*||18kg||£5300|
|DarkFrame NEQ6 (6.3.x)||7.5 (±28 ∆)||1.4||2.0 (5.9)∆||0.25 (1.5)∆||20Kg*||£499|
|DarkFrame AZEQ6GT (6.3.x)||7.5 (±25 ∆)||1.4||1.0*(6.5)∆||0.25 (0.8)∆||20.3Kg*||£529|
|StellarDrive 6 Series||3.25-5.0 (mfrs*)||1.4||>1.0*||0.16-0.25*||20.3kg*||£799|
Key: *Customer/Test data ^PemPro/PPEC/TDM **PHD Data ∆ (stock)
Have a read of this data table for other brands and models: http://lambermont.dyndns.org/astro/pe.html
Table 3 is a new table This answers the question concerning real Periodic Error (PE) performance. This data will make you think: Why bother buying a more expensive mount? Well, as you can see they do offer serious performance. For a serious price. The limiting factor is our wonderful UK Skies. If you are thinking your needs are more than your EQ6 can handle, start saving. Payload is the biggest advantage these more expensive models offer as well as amazing design and build quality. What is interesting is that our mount Bonneville EQ6 rebuilds meet the Pierro Astro EVO6 head-on with similar PE of circa ±8 arcsecs. The EVO6 has impressive performance from a geared platform, and with a precision RA worm gear. Ours though is with the stock worm gear. StellarDrive's have precision worm-gears in both axis that take the periodic error circa ±5 arc-sec and matches the Takahashi EM200 of which it is an almost copy of.
Interestingly, the new Sky-Watcher EQ6-R is shaping up to be a great mount. Heavier than the other 2 sixes, (that'll explain the handle then), it's higher build quality and architecture moves the game on. Like the others, I'm sure it will have quirks of its own, but we've too noticed a re-calibration of the payloads to make the EQ6-R look better. It does perform better than stock, matching a tuned EQ6, but we have also improved the performance of the StellarDrive 6R, nearly doubling its performance, perhaps making it the ultimate 20kg class imaging mount. It is worth upgrading from your EQ6? Not really if you look at the sums. A tuned EQ6 will match it though and is few hundred cheaper. Is it worth it over the AZEQ6GT? If you don't need the AZ feature then yes, and in the UK market it is a lower price than the AZEQ6GT. I'm certain they wanted to pitch the EQ6-R at a higher price, but again a tuned EQ6 mount is a great leveller. In the UK and Northern Europe at least, the skies are the speed limit.
Our efforts with releasing more performance from Celestron mount has really started to bear fruit, especially on older mounts. Our recently launched StellarDrive AVX-R is already slotting into 15-20min guided images with ease, with 30 minute exposures now in reach. We can't wait for definitive data to publish!
What is proven beyond any doubt is that we have defined that tuning your mount works! The data proves the fact, with data to back it up. Now, the skeptics among you have doubted this, but this is fact over opinion. Mount tuning was always seen as a slightly dubious affair, but these results prove there is now a genuine alternative, that allows you to access more of the Deep Sky at lower cost.
The previous upgrade path of jumping from an EQ6 straight to an Avalon/Mesu 200 solution is now thrown sharply into focus. It isn't always needed, unless you plan for bigger telescopes. There's more choice in the middle now. I've added the new Celestron CGX, CGX-L, Skywatcher EQ8, and the iOptron CEM60, as they are newer intermediate class of mount, and all over £2200. Our New StellarDrive 6 is a new Sky-watcher based platform that meets that higher end mount performance envelope at a ground breaking price below all of these, with aerospace grade components such as our SPX Worm-gears in both axis. Just as accurate and cheaper.
If you search the web, you'll find similar data on the mounts listed in any of the tables. These tables are not skewed to make any mount look more favourable than another, not even mine! No point boosting/trimming the figures, anyone can with a guide camera can test their own mount for themselves. However, your mileage will vary, as how you set up your mount is more important than your seeing conditions.
We have had to recall and validate customer mounts with 60 minute single images, because they doubted the capability of our mounts. We found nothing wrong. We did this under warranty, which means our mounts have proven to be very reliable tracking platforms. In fact, latest data illustrates this with 0.9 arcsec per minute drift, at 5000mm (5 meters) focal length on Jupiter and just 0.66 arcsec/min sidereal. Unguided.
We took several customer tuned mounts with similar 4000-5000mm focal lengths and ran the same tests on Jupiter and Sidereal, and came back with equally similar results. We're still testing, as the less than 2 pixel per minute drift (@ 0.36arcsec/pixel) on sidereal means we can in the future calculate an unguided exposure vs focal length...
However, as illustrated in these tables it proves that your existing Sky-watcher can be brought up to date and refreshed very cost effectively, to match other EQ mounts costing at least £1200-£4000 more from new. Importantly, our mounts are much more reliable (and quieter) over longer exposures than a factory mount, because they have been setup and optimised individually. Data on our latest Build Type v6.3.x with its enhanced build package improve guided performance by up to 0.3 of an arc-second over the previous build type, and at least twice as good as any Rowan Belt Kit install you'd attempt yourself. All of this contributes to more reliable imaging, even in poorer seeing conditions. It's not just all down to the figures though. Like any mount, it's how well they are made. That is what you are paying for, and the high end mounts are worthy of such distinction.
I have both Celestron and iOptron tables updating as an ongoing basis as well. We have enough comparable independent customer data to publish built up over the past three years to go with the above, but less PHD2 data than we would like on tuned mounts. We have also started modifying more of these mounts which in time formulates a viable Build Type, for consistent production values. Also my research online to find more comparable data is also added in to the median values stated. Please send any guide data you have on your mount especially Meade/Celestron, and I'd be happy to add it to the tables so that others can make more informed buying decisions.
You can e-mail me at email@example.com for truly unbiased advice.
Hope you find the above useful.