Data Updated: 14 NOV 2022

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If you want to know how good your mount is compared to everybody else's you've come to the right place. Or, if you're thinking about a new mount or tuning the one you have and need to decide if it's worth it.

I try to update at every few months or so, to refine the data and add to it. This is truly independent customer data unless specified, in one place. You can do your own research, and please do, but none of this is skewed, as you'll find similar data elsewhere in online owner reviews and forums. It has come to light that some keyboard warriors on several forums worldwide have disputed this data. However, if do your own research, will find that this data is real, accurate and achievable. 

We have also conducted our own tests with our own specially developed SIDAC-36M test rigs, which we use for tuning QC/QA and modelling solutions for our own mounts. These are very high resolution physics based, repeatable tracking tests. Data integrity is all, so it serves no purpose at all to mislead anyone with inaccurate data. If you think any mount is misprepresented here, please e-mail and let me know. I'm sure we're all interested in real-world results, not factory claims.

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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 less than 2 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, with a DLSR or CCD/CMOS, guidescope and guide camera or OAG.  Your Imaging Pixel Scale/ Guider Pixel Scale Ratio dictates tracking success! No point having a mount that can't achieve balance, or track erratically or worse than your imaging pixel scale. With guiding, some mounts are more equal than others when achieving this. Yes, you should also get what you pay for. If you can balance and polar align precisely, then you are halfway there. sadly, this isn't always the case. 

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All the information supplied is independent owner averages over a 4 hour session. It is real-world data unless stated. Your mileage will vary. But before you beat up on your dealer/manufacturer (or us!) for claiming to supply you a lemon of a mount, (and it is statistically likely it won't be) it's down to you to demonstrate it as fact with some tests yourself. 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. You won't. 0.36 of an Arc-second is a 10,000th of a degree! Work with your supplier/dealer if there is a genuine problem with your mount. Most of the time, it's something simple.

All EQ Mounts do benefit from running-in and good practice, be it from us or from a dealer. 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, Focus, lubrication and wear, Age of mount, Balance, Guide setup, backlash even voltage! That's 13.8v/5-8 amps dedicated power supply for you EQ6'ers by the way for a much less spiky RA graph, not a 1.6A laptop adapter... ;-)

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The common rule of thumb was to take off 1/2 to a 1/3 of the stated maximum payload of a low-end mount, especially if you're astro-imaging. S'not fair you cry! But it makes sense. Sort of. All mounts have a sweet-spot. This applies to any low-end 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. DEC is positional, so a flat(ish) DEC line in PHD demonstrates excellent polar alignment, and mount that should track really well.

Most low-end mounts are not fully optimised as they built on a production line, to a median build standard, for consistent output. Our rebuilt mounts can run at full stated visual payload and still track sub-arcsecond, so it moves them often at least one class up. This is because each mount is fully optimised indivdually, and that can't be done on a volume production line. So an EQ6 with an 18kg payload can now image at a full 25kg, very reliably to the point you can go to bed... when you wake up, you'll have a stack of useable images with very few, if any lost.

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Have a read of this data table too: http://lambermont.dyndns.org/astro/pe.html

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This list which has been around for a while and 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.

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So why is guiding such a mixed bag? It's your sky that's the real culprit, and to be blunt, your own ability It's a physics based hobby so you need to understand whay stuff works, and why it doesn't. It is the equaliser of all equipment, the low and the mighty. 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 8-10 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. Not only that, but your guiding to imaging scale is crucial. No point having a guide camera guiding at 9.2 ArcSec/pixel, when your imaging camera and 10" f5 telescope is pushing 0.34 ArcSec/pixel. Don't, just don't. It will not be fun.

Best to start using a small 70mm refractor even at f4.8, or a 150mm f5 Newtonian or 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, seeing is the speed limiter on this visual highway. Pixel Scale affects all of this too...

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If you read the above thread then 10 minutes tracking 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. Keyword is consistency.

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. So, yeah, that's about as independent as you'll get.

Some have even bought a mount from another dealer, obtained benchmark data (and don't tell us), then send us their mount! 

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, are owner modified mounts with PHD data. These are averages too, as they are all basically just bearings and a regrease, with various levels of outcome depending on the quality of the build. We see a lot of these mounts in the workshop, usually 3-6 months after they go off the boil. DarkFrame tuned data is our customer Reference EQ Mounts. 

Mounts like Avalon, Paramount, MESU 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 (Telescope Drive Master) Adapter, for the ultimate unguided performance.

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How do I make 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 and EQ6-R mounts. They've gone down from tracking 0.9 Arcseconds (HEQ5) to 0.36 ArcSec RMS and from 0.5 to just 0.16 Arcseconds RMS (EQ6-R) in our latest StellarDrive ULTRA builds. Doesn't sound much, but it equates to over 3x more accurate guided tracking.

Remember, you're tracking a star light years away so the movement is so tiny you can barely see it, it's 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.

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Image: Cropped Single Frame 72mm WO Megrez 72+0.8xFRIII (537mm focal length) modded EOS450D ISO100 3600secs (yes, 1 hour) on DarkFrame Hypertuned HEQ5 guided with QHY5L-II mono with 50mm WO Guide scope. I then took 2 more... On Dual bar with WO ZS71/EOS40D Guided Payload 9KG  ©2016 David Woods/DarkFrame Ltd

PLEASE Note: All StellarDrive/StellarTune/Sky-Watcher data is the Total PHD RMS value over 4-7 hours session. Other manufacturers data may not be, unless stated, and is being verified as data becomes available.

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Table 1 (21/08/22) EQ Sky-watcher - Arc-second Unguided/Guided Performance over 300 second exposures

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)

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Table 1.1  (21/08/22) Maximum exposure time vs dropped frames (4 hour session @900sec)

Key: *Recommended Imaging Payload = 2/3 maximum  **Avg Customer Data  ***tested OTA's on Reference Mounts to Bonneville Build Type v6.3.x/v6.2.x

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Table 2: (08/07/2022) EQ iOptron - Arc-second Unguided/Guided Performance over 300 second exposures

Key:  **Avg Guided RMS (Customer supplied)  @Focal length (tested OTA's on reference mounts/customer data) 

Table 2.1 (08/07/2022 EQ Celestron Arc-second - Unguided/Guided Performance over 300 second exposures

Key:  **Avg Guided RMS (Customer supplied)  @Focal length (tested OTA's on reference mounts/customer data) 

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Table 2.2 (15/11/2018) EQ Capable Meade mounts - Arc-second Unguided/Guided Performance over 300 second exposures
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Key:  *With EQ Wedge  **Avg Guided RMS (Customer supplied)  @Focal length (tested OTA's on customer data) More data please!!!

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Table 3 (21/08/2022) Higher end EQ mounts Arc-second Unguided/Guided PE Performance

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Key: *Customer/Test data  ^PemPro/PPEC/TDM   **PHD Data  ∆ (stock)

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Have a read of this data table for other brands and models: http://lambermont.dyndns.org/astro/pe.html

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Table 3: This should answer 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/European 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 rebuild meets the Pierro Astro EVO6 head-on with similar PE of circa ±8 arcsecs. The equivalent 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. It also means that a StellarDrive 6 GT can image sub-arcsecond at full 25Kg payload, instead of deducting 7Kg for a stock mount. The EQ6 version is still a little lower 20Kg due to its geometry, and build. The EQ6-R is a hybrid of the two internally, with some casting changes. Is it better than the EQ6? Yes, but not as great as the data proves.

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What is proven beyond any doubt is that we have defined that tuning your mount works, but ultimately there is a limit The data proves this fact. 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/EC, as they are newer intermediate class of mount, and all £2200+. The Celestron CG-X looks better value than the revised and price hiked EQ8-Pro. 

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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 "Bonneville" 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 (Flat Earth), 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.

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To Sum Up

High End mounts still have their place and always will do. Tuning your mount not only extends it's payload and usability, it helps train you for that jump to a bigger mount. Running your existing mount at higher performance, is the most cost effective step by showing you how you imaging improves with better tracking and guiding. Most importantly, it saves time.

The reliability that should be a given for more expensive mount, is now the same for a tuned mount. You can almost double the data in some cases, with no lost frames. That's the point, a good mount makes good images, but a precise tracking EQ mount, will help you make some truly great images.

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You can email me at dave@darkframe.co.uk for truly unbiased advice or to help add to this data.

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Hope you find the above useful.

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E&OE ©2022 David Woods/DarkFrame Ltd. All data is indicative of mount model performance and for illustrattion purposes only. Your mileage will vary with your own mount, and cannot therefore be used as any guarantee.  None of this data or content is to be re-published without the owners consent. All Rights Reserved.