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CG5-GT StellarTune™
£249.00 inc. tax

£207.50 ex. tax
? Tax based on United Kingdom.


Rejuvinate your old CG5-GT with a tune-up. We can make it smoother and quieter, as well as better tracking to take your Astro-imaging to the next level.


Our three-way UK Courier Service is just £29 fully insured using a tracked service, if you don't have original packaging. Choose this option at end of checkout.

Celestron Equatorial mounts by nature are precision made products. However, due to mass production and to keep the prices lower, they are often not fettled to the best of their ability due to the variances in each mount. Various improvements can be made to transform the performance of your mount from what is a median production build this will save you the need to upgrade to a more expensive mount, providing you are happy with the payload you have. 

Basically, we developed a faster and more accurate way to tune the mounts with consistent results. The GOTO with a 4+2 Calibration after tuning is amazing. We have been testing CG5-GTs AVXs and CGems as well as a CGE-Pro, to shakedown all the issues with these mounts over the past several months, in an effort to replicate the performance envelope we have with the Sky-Watcher's.


We will be keeping a close eye on all Celestrons for feedback, as we do on our existing builds. It makes for a better mount. The results from the Celestron Reference mounts have been encouraging, and have formulated special builds for each mount, as they all have different solutions. You will not find any references to sanding down components here! We have always taken a far more engineered approach.

The Celestron mounts generically suffer from drivetrain harmonics which affects its periodic error which is well documented. I have largely been able to reduce this by reworking the reduction gearboxes, and reprocessing some of the internal components to eliminate internal stiction. Its a different architecture to the Sky-watchers which we have had much success with, and Im now focusing my energies in doing the same with the Celestron EQ Mounts. There is a lot more engineering work needed with all the Celestron EQ mounts, and this makes them more labour intensive (but have to say more interesting) as the way the drivetrain works makes it harder to get a desirable PE profile for guided or unguided work. That said, it is possible to go up to 45min exposures with the use of QHY Polemaster.

EQ mounts are subject to being outside and often in the damp, so renewing the grease is often a first port of call, using a better type of grease more suited to our climate can help reduce friction. This means the motors can drive the mount a lot more accurately both unguided and guided compared to a stock mount. We service the gearboxes from what we have developed with our Ambient tuning techniques, and in doing so make them run quieter and smoother.

Also, with much more care in adjusting the worm-gears and motor drive train, they can often be made to run smoother and quieter throughout, which also benefits better tracking and periodic error reduction. 

What's the difference between a Service and a Tune and a Repair?

Our Mount Servicing is effectively to bring your tired mount back to a factory fresh setup with backlash adjustment and using standard greases and oils. However, if there is any damage, or wear, then new components may be required at extra time and cost to put right. Like a car, you cannot tune a sick motor, so we evaluate every mount before we attempt to tune it. 

Our Hypertuned mounts are better than new, with more response and less friction than a factory mount. This equates to better guided and tracking performance, as proven by our customers PHD2 guide data and their amazing images! Not only are nearly all mounts independently tested by our customers, they paid to find out how good they are. The guide logs we get back from them have helped us produce what is the most cost-effective and reliably performing mount that gives an EQ8 a run for its money!

Check out how your mount compares in our performance charts.

Our tuning methodology provides a more detailed approach, using higher performance lubricants that help the mount perform better, which have been tested extensively over several years. 
We also clean up the castings and can upgrade the worm-gear bearings for a better drive response.

If required, we can also upgrade the main DEC and RA axis bearings as an option, but  this is rarely needed if the mount is new, as they only rotate 180º. We also load test the mount and take sound profiles, as well as stripdown/rebuild photos and video as part of the tune-up record.

What difference does your Tuning make? 
Our latest DarkFrame Generation Tuned EQ6/NEQ6-AZ EQ6 GT mounts typically run at a Peak-to-Peak Period Error of circa ±8 ArcSec), which is 3-4x better from factory spec. Guided, all our mounts are now sub-arcsecond capable under PHD2, running typically 0.5 arc-seconds RMS, with a guided PE of ±1.5 arc-seconds, depending on seeing. This is proven Customer supplied data across several mounts, not a factory test.
Our tuned EQ mounts become nearly twice a responsive responsive to guiding due to a lack of stiction in the mount, requiring less quide command input. Our unparalleled experience in EQ mount tuning comes from a scientific approach to development over the past thee years. it's not black magic or just a bit of grease! It is engineered to be better, with data to prove the difference. The new Celestron CG-X moves the game on but is an expensive option to upgrade to.


We have independent customer/owner supplied PHD data and images that demonstrate these facts across a broad spectrum of EQ mounts on a variety of payloads and real world data. So, if you're happy with the payload you currently have, we can improve the mount you already have and save you hundreds, if not thousands of pounds in buying a new more expensive mount upgrade. More importantly, you save more images and time! Please check out how your mount currently compares in our performance charts, especially if you're thinking of a more expensive move upwards.

Hypertuned EQ6 PE Data
PEC Data of NEQ6 to Build Type 6.3.2 (Bonneville).
What's the lifespan of your tuning/servicing? 
EQ mounts need checking seasonally depending on use, but most mounts we service are usually 3 years old or more. By 5+ years every mount we have come across has amassed considerable backlash and other issues associated with age, such as greases drying out or becoming contaminated, so losing their lubrication and dampening qualities. With the work we do, your mount should be fine for three years or more, and we warranty them for two.  New tuned mounts should be fine for 5 years. The condition of our 2 year old Reference Mounts support this timescale after a recent Build Type upgrade to v6.3.x (Bonneville).
When can I have my mount back?
Turnaround for our services is currently within 10 - 15 working days when booked in advance, and subject to condition Our builds are meticulous. They take an average of 3-4 hours with another 4-6 hours of run-time to bed in the mount. If it doesn't pass our test routines, it's doesn't ship until it does. We tend to get busy from the Spring onwards, and we limit our production to keep build quality high, so booking in advance is advised. We offer an easy three way collection and delivery service for £59 anywhere in the UK/EU. We send you a reinforced box, collect your packed mount and deliver back to you your smoother, better performing EQ mount.

Servicing, repairs, customisation and Tuning is available Celestron mounts using OEM parts.


Celestron Tuning Notes:

The CG-5-GT mount typically runs at 20-60 arcsecs from new unguided in independent tests. Once tuned our mounts run circa 4-6 arcsecs, and circa 1.0 arcsecs guided is often reported by our customers. In PHD2, your hypertuned mount is up to twice as responsive to guide commands. Backlash is virtually eliminated, which also improves point accuracy. EQ6/NEQ6 have a specific customised build called v6.3.3C which generates the NEQ6 as a benchmark for all our mounts, a providing consistent level of engineering across the range in this Build Type. It is possible to belt-drive this mount, but requires a lot of rewiring which outweighs the cost/risk benefit vs performace. 

Our latest DarkFrame Generation Tuned EQ6/NEQ6-AZ EQ6 GT mounts typically run at a Peak-to-Peak Period Error of circa ±8 ArcSec), which is 3-4x better from factory spec. Guided, all our mounts are now sub-arcsecond capable under PHD2, running typically 0.5 arc-seconds RMS, with a guided PE of ±1.5 arc-seconds, depending on seeing. This is proven Customer supplied data across several mounts, not a factory test.

The worm-gear shaft just spins with upgraded low-friction SKF bearings compared to the standard bearings, and even better still with our new Hybrid Ceramic bearings. These reduce the end-float, and provide a very solid feel to the mount, which in turn virtually eliminates the well known rocking motion in both RA/DEC. We calibrate the end-float to an accuracy of 0.01mm, to ensure a consistent dial-out of backlash and minimised play in the gear-train. 

Cleanup and de-burring of the castings is often needed as they are quite rough in places, and the mating surfaces contribute to better engagement of the worm-gear. We don't often change the main axis bearings, but we test them and replace if not smooth. These only move 180º over the course of an evening, so replacing them with ones tested to 20,000rpm is largely academic! :)

Once tuned, 10-15min subs are more than possible with this mount with very few if any lost frames. 30 minute exposures is near the mechanical limit but is achievable with lighter OTA setups with this mount without substantial re-engineering of the mount or the worm gears. This is currently under research and development. 

The AVX is better engineered, and tests have shown this to run up to 40 mins but is largely unwarranted the UK, unless you're narrowband imaging, or running long focal lengths. Check out our testimonials page, for examples of our work.

Add an optional Geo-Position Pack or Geo-Guide Pack, which includes as standard StarGPS and QHY Polemaster to your Celestron and your imaging is taken to a whole new level, especially when guided. See related products  below.....

Celestron Performance:

Upgrading the worm gear bearings to Hybrid-ceramic items and belt-driving the motors substantially reduces backlash and improves periodic error. Tuned mounts run typically at circa 5-6 arcseconds RMS, and can be autoguided to consistently perform sub-arcsecond tracking with practice, especially when allied to a QHY Polemaster, and well driven via PHD2. We will advise you of the new settings as a basis to get the most out of your rebuilt mount.

We have CG-5-GT, AVX and CGem Reference mounts that are utilised to constantly improve our Zero Drop Frame tuning methodology, and demonstrate the benefits of enhancing the mount. That's the point, you can do more imaging with our mounts.

Here is a customer supplied PHD graph of one of our EQ6 Mounts. Other customer supplied examples are available upon request, and we will be updating them with Celestron versions as they become median values.

PHD Graph of Tuned EQ6 Mount

Work includes:

Each Celestron EQ Mount is examined externally for any damage and owners are notified for any extra-parts if needed. We photograph dis-assembly and reassembly of key components, and video before and after with a sound check that creates a unique sound signature for each mount. A unique report is available for an extra charge.

The Mount is stripped back in both axis to component level, inspected for damage or wear, and degreased. Owners are notified if any extra-parts are required or upgraded by request.

Axis bearings are degreased, checked for wear/damage and ultrasonically cleaned and re-lubricated, as are the bearing cone surfaces checked and cleaned in the mount. The Crowns are StellarDrive™ reprocessed to reduce friction in the casting, and to promote smooth running. We do not use sandpaper on brass, or endorse it's use in any of our mounts.

All external threaded bolts on mount and tripod (if supplied) are degreased, ultrasonically cleaned and re-lubricated. 

Mount is reassembled using upgraded greases and oils which operate in all temperatures from -25ºC to +50ºC (we use them in our Export Service and our own products so have been tested at these temperatures!). 

The Mount is then bench tested and adjusted to dial out backlash and to ensure operation of mount, for 4-6 hours to bed the mount in, then checked again prior to boxing for dispatch.

GoTo Handset and Mount is checked for Firmware updates and updated with latest code as required and tested for operation.

Free fitting of QHY Polemaster adapter if purchased and camera test to ensure correct focus and operation.

In the case of axis repairs and tuning we carry out a load test on every mount with either an 8 inch reflector or 100mm f9 refractor - or 70mm refractor for smaller mounts. Worm backlash is then dialled out as much movement a possible so to ensure the mount is performing as it should under real-world conditions. 

Mount is then readied for shipping/collection. Our three-way UK Courier Service is just £39 fully insured, using a tracked service, if you don't have original packaging.

The mount is videoed/photographed during evaluation, disassembly and rebuild, with a soundwave check to confirm drivetrain signature. A Mount Report is available for and extra charge. All work carried out is now covered by our 24 month limited warranty.

E&OE - Mount Build Specification and components used subject to change without notice. Example EQ mount tracking performance is not guaranteed, and is subject to the age and condition of the Donor Mount.


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Product Code
- cg5-gt-gen0
Product Condition
- New


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    11 Drift Road, Clanfield, Waterlooville, Hampshire, PO80JJ, United Kingdom
    +44 23 9257 0283
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