The 4th Pier: Galaxy Scope, Part 2 - The Mount!
Date: March 8, 2025
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Where We Left Off
Based on my first post on my project to put together a galaxy scope, I made decisions that pretty much describe the OTA I would build.
That post can be seen HERE.
The Optical Tube Assembly will consist of:
Sharpstar SCA 260 V2 (1300mm @ f/5) Scope
ZWO ASI2600MM-Pro Camera
ZWO EFW 32mm x 7
ZWO AOG-L
ASI 174MM-Mini Guide Camera
ZWO EAF Focus Motor
The Mount
But the mount was still a very open question.
At the time, I was leaning towards a SkyWatcher CQ350 Pro or perhaps a SkyWatcher 150i Strainwave Drive.
As I continued to research this question, I was plagued by two main doubts:
The CQ350 is a relatively new product, and little performance information is available. Would this work well for me?
Strain wave is cool - but is it the best solution for the observatory environment? Is it the best mount for the loads being considered?
Asking For Input
Finally, I decided to tap into the greater Astrophotography community's Hive mind for wisdom!
I posed the question to several Astrophotography Interest Groups on Facebook and sat back to see what input I might receive.
Here is my post:
My plea for Help!
I ended up getting a pretty significant set of responses!
This must be a common question that folks wrestle with, and I received a lot of very good input - all of which I really appreciated! You can follow the link Here and see the responses yourself, but let me summarize the input here.
The first takeaway is that there is a broader set of mounts that I might want to consider. In fact, several of the mounts mentioned were offerings that I had never heard of before!
Let’s look at the various recommendations made.
Astro_Physics and 10Micron
I had several people suggest that I go the high-end route. There is no doubt that these would be excellent solutions, but they are well outside my current budget reach. Sure, that would be nice, though!
JTW Astronomy Friction Drives
I had three people make this recommendation.
I never heard of JTW before, and I was fascinated to learn about their offerings.
These friction drives seem very high quality, and those with them seem delighted. The price is very reasonable for the quality they seem to offer.
Again - this is a bit outside my current budget.
Sky-Watcher EQ8-R
I had identified this heavy-weight mount in my first post. However, I did not get a single person recommending it in the responses I got.
I must admit that I was a little surprised by this.
But, had already eliminated it as it was outside my budget.
Agena Astro Link:
Sky-Watcher EQ6
I had two people recommend this mount.
It is a classic mount, but I think the weight I will ultimately be dealing with is a bit heavy for its rating.
Some people are using this successfully, and I don't doubt that - but for me, I would prefer something with a larger weight rating.
Agena Astro Link:
https://agenaastro.com/sky-watcher-eq6-r-pro-computerized-goto-telescope-mount-s30300.html
Sky-Watcher CQ350
I was already interested in this one, and I heard from five people who loved it and highly recommended it.
I also heard from one person who thought it was awful!
His concerns?
“Dangerous to your fingers due to its design, locking knobs tend to fall out for no reason, very hard to cable manage due to the design, “mid” guiding performance, and if it’s more expensive than cem70.”
I would say this is still a very interesting mount that is within my price range.
Agena Astro Link:
https://agenaastro.com/sky-watcher-cq350-pro-head-with-counterweights-no-tripod-s30820.html
Celestron CGX-L
I had two people recommend this mount.
It is certainly heavy-duty. It has also been around for a bit, so it is proven.
However, the hand controller is the only way for your computer to connect with it. I had a CEM26 mount that worked this way, and I found it clumsy and awkward. I would not like to repeat the experience.
I have no doubt that it does a great job, but, I would prefer to go the other way.
Agena Astro Link:
https://agenaastro.com/celestron-cgx-l-computerized-mount-no-tripod-91531-2.html
Losmandy G11
These mounts are glorious examples of machined metal. I had two people recommend this option.
I have an older version of one of these mounts, so I have some experience with them.
There are three aspects here that I do not like.
They use a slip-clutch design. I would align and sync the mount; then, when walking around it, I would bump it and lose my alignment. I found that frustrating.
In my experience, cable management can be a bit of a nightmare with these.
I also thought the Gemini 11 control system was outdated and awkward.
So, this was not the right choice for me.
Ioptron CEM120
This is a beast of a mount, and I know several people who are using them and getting outstanding results.
With a 120 lbs rating, they can handle my load and any future load I could imagine.
I also think they are an outstanding value at their current price point.
But, alas, the price is still outside my budget.
Agena Astro Link:
https://agenaastro.com/ioptron-cem120-center-balanced-goto-eq-mount-head-7300.html
Ioptron CEM70
Six people recommended this mount.
It fits my budget. It had a 70 lbs load capacity.
It's been around for about 7 years, so it is a tested design.
That sounds perfect - right? Well, I have been unsure. I have heard reports of DEC backlash due to belt tension. Correcting this consists of loosening the dec stepper motor mounts, leveraging it with a screwdriver, and then re-tightening the mount. Not exactly a precision method! It was also similar to how you had to do it on my CEM26, and I hated that. So I was unconvinced.
However, no one who had the mount that recommended it had any backlash issues, and at least one person suggested that there was a big step up in quality between the CEM26 and the CEM70, so I should not be overly concerned.
We shall see.
Agena Astro Link:
Rainbow Astro RST-300
Now we get into the strainwave drives.
This one was one of the very first.
One person recommended it, but it is well outside my budget.
Proxysky UMi 20S
This is another mount that I was not familiar with.
It is a Strainwave mount and was recommended by three users.
It sounds like it has several features that some of the other mounts do not - such as a collision avoidance system.
It would fit my budget.
But is a Strainwave the best solution for me right now?
ZWO AM5N
This now classic mount had five people recommending it.
It seemed to me to be a bit underpowered for such a load, but obviously, some people are using it successfully.
I have one and absolutely love it. But is it the best choice for a larger load with a long focal length?
I also saw two different videos showing the AM5/N stalling when slewing such a load.
It seems to me to be underpowered for heavier loads - to me. Others would argue and show amazing images that validate their choice.
Agena Astro Link:
https://agenaastro.com/zwo-am5n-strain-wave-equatorial-mount-head-new-am5.html
Sky-Watcher 150i
I had two recommendations for this one.
It is priced roughly the same as the AM5, but it is rated for a heavier load, has superior cable management, and finally - has the ability to loosen locks on the axes so that true balancing can be done.
I find this to be a very interesting offering!
Agena Astro Link:
https://agenaastro.com/sky-watcher-wave-150i-strain-wave-drive-mount-s30905.html
Warpastron WD 20
This is another Stainwave solution that stands out from its peers.
First, the fit and finish of the machining is superb.
Second, it is one of the few mounts out there using a direct servo drive with motor rotation encoders rather than a stepper motor/belt solution. This provides superior torque, quieter action, and supports a heavier load.
It is a very interesting mount.
The are some downsides:
It’s about $1000 more than the other Wave Strain mounts mentions
It uses OnStep driver software - which is a little odd to work with using non-standard nomenclature and other oddities.
It also requires a narrow and regulated power supply and cannot handle power of more than 13 volts. Many 12v systems are very forgiving of voltage range, and this one is not.
Agena Astro Link:
https://agenaastro.com/warpastron-warpdrive-wd-20-strain-wave-eq-alt-az-mount.html
So Where Does That Leave Us?
By necessity, I must eliminate those mounts that are outside my budget. That leaves two traditional mounts and three strain wave mounts, which I was interested in.
The Traditional Contenders
Sky-Watch CQ350 Pro
Seems like a nice design
some dumb electrical cabling decisions were made in the design.
Not common - they are becoming more known, but it is early in their life cycle
It seems to have an intelligent Backlash adjustment system using a screw mechanism
IOptron CEM70
Now, 7 years into its life cycle - there is much experience in the field with them.
It’s had a lot of success in the marketplace.
There are some limited issues with backlash - and while I am not crazy about the adjustment method, it appears not to be a big issue
Few people seem to have problems with it.
The software driving it is pretty solid and Familiar to me as a user of the CEM60 mount.
Mounting it will be easy and inexpensive as IOptron offers a cost-effective Top Pier Plate.
The Strain wave Contenders
WarpAstron WD-20
Interesting design
There is no way to balance easily
OnStep software is weird and seems to have issues that must be navigated.
No maintenance belt-free system
Solid PA adjustment mechanism
There is a need for a well-regulated 12v supply required - nothing over 13v
It has not been around long
It's as expensive as some traditional mounts.
ZWO AM5N
Commonly used
Excellent track record
Attractive price
It is a little lightweight for larger scopes, though people are using it for larger loads
Videos of it stalling reinforce heavy load concerns
There is no way to balance easily
Cables attached to the moving head
Belt drive - so some future maintenance is assumed
Sky-Watcher 150I
Good design
Easy balance
heavier load than AM5N
Attractive price
Belt drive - so some future maintenance is assumed
It's pretty new - not much of a track record.
My Final Choice
My first decision is that I will not go with a Strain Wave drive at this time.
Why not A Strain Wave?
Lots of people are using one with this class of scope, and I like the technology - but:
In my humble opinion, they seem better suited to portable applications and smaller scopes than to larger scopes in an observatory setting.
Many Strain Waves have not yet stood the test of time. How will they age?
On most models, I would be eating up a lot of weight rating right off the bat with little room for heavier loads, so perhaps it is not as future-proof as others.
In many cases, the software is still a little dodgy.
So - A More Traditional Mount - But Which One?
I’ve decided to go with the IOptron CEM70.
Why The CEM70?
It is one of the most mature designs and seems to be standing the test of time.
It has plenty of extra weight capacity for future-proofing
It is similar to my current CEM60 mounts
which have been rock-solid
and would be very similar in operation and use
The software and drivers are mature, stable, and familiar to me.
Mounting on my custom steel piers will be very simple by leveraging IOptron Top Pier Plates, which are inexpensive.
It fits in my budget - and in fact, I think they are a good value
The supply chain has them available - where others are tougher to find.
The biggest knock I had on the CEM70 was DEC Backlash issues and the clunky re-tensioning of the belt drive. It seems this is less of an issue, and the adjustment is not such a big deal. Many mounts use belts, and over the life of ownership, I think it is reasonable that some maintenance will be necessary. I have come to terms with my concern here, and as there are many other positive issues for me, the decision becomes clearer.
This seems like the best choice for me - but it may NOT be the best choice for you and your circumstances. I thought I would share my thought process, hoping it may help you make your choice as you make it!
The Order
I will be ordering the following items:
A basic CEM70 mount with IPolar
An extra 21 lbs weight
An Ioptron Top Pier Plate
I’m holding off a bit to see what our tax bill is this year, but my intention is to order one as soon as I can so that I can beat any additional tariff nonsense that may affect pricing down the line!
Stay Tuned!
I will be posting on my efforts to assemble this platform and get it into operation!
