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05/18

Catseyecollimation Logo 75mm x 26mm - 1200 DPI clbr 8k Complete SX SMLLLogo 8k Complete SX SMLLLogo OPT-front-page-logo_6bfc163f-8f79-44ad-82ad-053c67b30457_250x Capture zwo_brand_logo ISSUE57 PUBLISHED

Now just from the title you'll probably think I'm being biased! But actually it's impossible to beanything by pragmatic. I've published so much data on this you can really see the differencesyourself. However, the question isn't just about which ones better on paper but one of economics.Like any hobby it comes back to that cost vs use equation. The more time you use something thecheaper it gets. If you only spend 10 nights a year imaging and $4000 on your gear then that's not exactly a cheap night out! Of course, that's an extreme example. But the elephant I the room, when it comes to astronomy equipment, is about life span.Telescopes are actually very simple devices and in that respect, providing they're perfectly stored in a dry, dust free environment then there's no reason why an aluminium tube telescope wouldn't last decades. I know of a 120 year old Cooke Refractor made of brass whose F15 brass tube was displaying 'stretch' marks 

Hypertuning vs new mount

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as gravity started to take it's toll. But it still held collimation and provided stunning views for it's age. Though a SkyMax 102 Maksutov was proof of how far modern mounts had come by comaprison. The physics of telescopes remain unchanged and immovable through the passages of time. Mounts however, are far more complex.It's just not the physics needed to make them that make them suchspectacular pieces of engineering but there is a natural obsolescence to these mechanical mounts.

Here is the inside of a Celestron Gearbox. Some of the harmonic generated in Celestron EQ mounts come from here and while it’s possible to reduce the amplitude with better lubrication, the original grease will breakdown. It’s actually the transfer drive gears that cause the problems. Now you know why they can be noisy.

Quite simply, they will wear out. It's not such a revelation if you think about it.Up until now one has really had any data on how long these mounts actually last for. Modern EQ mounts over the past 20 years have a lineage tracing back to the 1950' & 60” (and older). And as astrophotography started to take hold in the mid 1990's, with Meade in particular developing Schmitt-Cassegrain telescopes for the masses, photography was only ever going to become more popular. However, they were Alt-Az based and required a wedge for any longer exposure imaging. The disruptive technology to all of this was the advent of Digital SLR's coming on to the marketover a decade ago.

 

Since then there's been an explosion of rapid advancements in astro-imaging, processing, and of course DSLR's.The problem has been that around the same time the venerable SkyWatcher EQ6 was seen as the benchmark for an astro imaging EQ mount. It's still holds this mantle to today, even though it's design has changed little since launch. It still remains an effective mount. With EQ MOD and various iterations of belt drive kits supplied by third parties, strip down and re-build guides started to appear. Ed Thomas of Deep Space Products was the first company to commercially launchHypertuning in the USA. Basically, he 'invented' and his trademark 'Hypertune' has now become part of the language. With Astrotroniks arriving a few later, both have different methodologies in mount tuning, and are worth checking out if you are Stateside. Other smaller mount tuners have come and gone since then and their main failures have been due to their lack of understanding of how to service a mount properly, and being unable to convince people that it can work.  New mounts are built on a production line to a median build standard. If they spent as much time as I do sometimes rebuilding a mount then their production would grind to a halt. There's a lot of engineering in mounts, and this is often not understood or appreciated by many. PHD is a guiding software that people use to benchmark the performance of their mounts, as do we.It's more than just about Arc seconds and periodic error though, it's also about taking reliable images.

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There's absolutely no point having any mount that drops 30% to 60% of your frames over an imaging session. With a new mount or even one that's been rebuilt, there is a 15 to 50 hour running in time. I state this quite simply because these gear driven mounts have to bed in and the worm gear/crown ring have to lap into each others threads over time. Given the slow revolutions of these drive trains that takes a long time to happen. Some mounts willsettle from new and often this is when backlash occurs. On all modern EQ mounts with worm gearsthe adjustment of this using the manufacturers instructions will improve matters greatly. This can be achieved by loosening off the work gear casting in either axis so that the bolts are loosened just enough to allow the casting to slide. Using the grub screws which provide a push/pull arrangement, you can alter the engagement of the work gear to crown. Word of warning though – engage too much and the motors will bind, too little and you'll get backlash. Once you have adjusted this, so the motors are not straining and have a constant even tone whilst slewing, then you have achieved your goal. Please always refer to your Owners Manual for more details on how to adjust your worm gear as each mount is slightly different. Eventually though, you'll be trawling forums for more information and for more advice and wondering why your mount feels overdamped and tight. There's a reason why manufacturers use a very stickygrease - it's there to dampen the movement and provide longer service. The thing is, that this greasenot only smothers performance but it degrades over time just like all greases do.So when online strip down guides for EQ6 were published by people who thought that servicingwas a great idea and anyone could give it a go, many owners took the opportunity with varyingoutcomes. I'll buy a pint for for more advice and wondering why your mount feels overdamped and tight. There's a reason why manufacturers use a very stickygrease - it's there to dampen the movement and provide longer service. The thing is, that this greasenot only smothers performance but it degrades over time just like all greases do.

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So when online strip down guides for EQ6 were published by people who thought that servicingwas a great idea and anyone could give it a go, many owners took the opportunity with varyingoutcomes. I'll buy a pint for  the first person than can show a blog or posting that shows where it all went wrong. On the internet, success is democratised, but failure is seen as failure - not learning.Going by the sheer number of basket cases we have had in our workshop over the past three years, there are a lot of mounts out there that aren't as successfully 'rebuilt' as some of the forums claim... In fact, my hands are somewhat tied. I have read some truly horrific advice on how to take apart a mount, involving boiling water, hammer and saws! I'd love to respond to these posts but forums see me as a trader or manufacturer and therefore automatically 'touting' for business. But actually it serves the entire community if people understand that these are precision instruments and not lawnmowers.

 

What's worse, is that these tuned mounts usually end up with me...If you can imagine what would happen to your car if you didn't service it for 10 years, or even abicycle. No one has ever stopped to think that these mounts might not go on for ever. But if they did would you buy a new one? So here I write - playing Devils Advocate - and you're probably going to wonder what all this blathering is all about. Take a deep breathe – here goes.....Think of your equatorial mount as a Tracking Engine.Unserviced, an EQ mount may last up to 20 years or more, however, it will require a minimum of servicing every 5 years.  If it's under heavy payload or in damp environments, you can reduce that to three. If anyone has any data to dispute this then we'd welcome it. :)  I'm sure the other few mount tuners world wide would probably concur with their experiences too. If you use bicycle grease (!) orsome other automotive lubricant then the only way you will prevent wear over any period of timewill be re-building the mounts bi-annually. The greases used are not available outside original equipment manufacturers (OEM) in small enough quantities to make it viable for people to buy.The lubricants we use work out at about £3.00 per gram and many people would not want to spendthe amount of money needed to properly lubricate a mount. Hypertuning has always been seen as 'snake oil', which, of course it's not – it's a range of solutionsfrom simple fixes to engineering science such as Tribology. We are the only mount tuning company to publish totally independent data from our customers on their own mounts. Our customers have paid us to find out how good their mounts are – remember?

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Celestron CGEM-DX. This mounts grease had already degraded, and was not the original type. When contaminated grease will turn black.

Tribology is an engineering science based around lubrication and surface interaction, so the originalmounts tuners had the right ideas it's just that it's now been taken to a higher level. This level of surface finish is normally reserved for more exotic mounts at considerably higher prices. A lot a what we do now is encapsulated under our StellarDrive range of mounts which uses a patentable process that makes it more cost effective to apply to low end mounts (Col. Sanders watch out!).It's also a case of 'Triggers' broom. You know – the reliable broom that's last 20 years but has had 4 new heads and 3 new handles, and was the most reliable broom he had ever owned! I guess that's where Hypertuning came about too, because you can take a stock mount and you canmake it perform amazingly well – we've proven that. Though in the early days it was met with much scepticism partly because the majority of owners don't really understand how their mounts work. But with the ever unstoppable advancement of digital imaging mounts are now being seen as the important hub of any imaging rig. It takes a long time to develop new mounts and the marketplace, in commercial terms, is quite small. Some of the newer mounts coming on to the market do perform incredibly well. But it's more of anevolutionary thing than a new generation.

In Northern European skies, which are getting milder every winter, the key factors are not about outright performance, but that of reliability.  Being able to access long exposure guided images on a continual basis means that you can image for deeper, longer and more often than before. New mounts may or may not provide this, because they are built to a median level of quality control.

 

Newer mounts like the EQ6R benefit from architecture that makes them more reliable but there's no point spending huge sums of money on more expensive mounts unless it's payload you're after. I've just finished tuning an EQ3-2 and the thing for me, as with all our mounts, is to work on unguided performance. If it can do that well, then guided performance should therefore be a doddle.Our HEQ5's and EQ6's have already been tested to 600 second exposures with an 80mm ED refractor and the target during 2018 is to improve this to 15 minutes if we can unguided and for small mounts like the EQ3-2 and EQ5 to run to 10 minutes unguided. Once polar alignment, balance and levelling are managed then all a mount has to do is to track a Star. On these moreelemental mounts lubrication becomes all important, an EQ3-2 has about 106 Arc seconds peak to peak periodic error which is the main reason it struggles with unguided imaging, even from new.It's possible to do long exposures with fairly short focal lengths, but it quickly falls apart once you start using anything other than a camera and lens. However, once tuned the EQ3-2 can prove to be quite an amazing device with a periodic error to match a stock EQ6! EQ5's are often sold with a 200P telescope and as stated in last months Editorial – it's often overwhelmed. Now the key take away from mount tuning is that instead of losing a third to half of your payload when imaging, if it'sdone properly you should be able to use all of it.SkyWatcher have positioned their EQ6-R as a full 20kg payload mount for imaging, whilst demoting the NEQ6 and AZEQ6GT to 18kg depending on where you read. We've tested the AZEQ6GT and the NEQ6 to 20kg at sub-arc second imaging and unguided both mounts run sub-arc second per minute! Meaning – they track incredibly accurately – it's pot luck if you can match that with a stock mount. The internal stiction is too much for the mount to track properly and besides most people are running at the wrong voltage anyway.

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Lithium Grease. Too much is really bad for your mount and we see this a lot. This poorly HEQ5 was rebuilt and validated to 60 minute images!

As you can see from some of the images with descriptions – we've had some really horrific mount rebuilds in from customers over the years. Usually they're done on a much older mount as new ones generally perform quite well. We have noticed a natural pattern that people start to rebuild their mounts after 5 years anyway, supporting my advice for servicing. So – here's some tips if you're going to attempt Hypertuning yourself....Be aware that greases do degrade over time and like cars have different viscosity ranges. Not all of them are suitable for use in telescopes. Lithium is not a bad alternative but can emulsify, dry out or separate over time. Using low melting point axle greases is not a good idea, neither is engine oil(!) because they can also contaminate the surfaces. If you do decide to use a Teflon (like TF2) based grease – just remember that it's performance will tail off after 18 months to 2 years. Getting the right bearings for the worm gears and axis will improve your mount, they alsocontribute to periodic error and harmonics. Polishing removes material. Yes, it does. I've seen on one forum someone gleefully exclaiming that he polished the outside of the DEC sleeve bearing for a Celestron AVX, but basically he polished the clutch! You'd have thought he just invented Milk. Then everyone else does the same.

If you don't know what you're doing – do not attempt to refurbish a mount. Online Advice is based usually around one mount, one solution, but rarely will you read the result. Regardless of what some people claim these are precision made instruments which are trying to track a star on a revolving, tilted Planet often using batteries.If anyone thinks that it's easy to rebuild a mount, especially an older one, try spending 4 days fixing that mount in a fully equipped workshop and then try claim it can be done on the kitchen table!Older mounts take more time to revitalise, and realisitically providing useable performance ratherthan something mind-blowing. It comes down to cost.As the population of mounts become older then more problems will arise as astro imaging becomesever more demanding. The smart move is to start thinking now about how you will be imaging in the future and how you'll be looking to upgrade.New or Hypertuned – You've always had a choice, now you have the reasons why.

 

David Woods

 

www.darkframeoptics.com/

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