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CEM26 on astro holidays - am I mad?

iOptron CEM26 Equatorial Mount Harmonic Mount
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GTom avatar
GTom avatar
Asked elsewhere but thought to venture in the mount's dedicated thread where maybe more owners can be found. Has anyone air traveled with the mount? I am getting embarrassingly expensive offers on the "budget" SA GTi, meanwhile second hand gem28, cem26 mounts are getting more and more affordable. Harmonic mounts are getting closer to my affordability limit (e.g. Juwei 17) but I have the feeling that many things are still not ironed out with them, e.g. unguided performance and fool proof handling of pier collisions…

Looking at the specs, the cem26 is "only" 2kgs heavier than the SA GTI, counterweight is defined by the precious cargo OTA = approx same in both case I suspect. That doesn't seem to be a huge difference re portability.
Dave Rust avatar
Dave Rust avatar
I’m using the HAE29EC with terrific success with a lightweight portable rig. Guide exposures at 2 seconds and guiding at .28 to .70 depending on seeing. Reliable, quiet, and lightweight. 

The performance is slightly better than that on my bigger rig with a CEM40, to the extent the two technologies can be compared. 

The CEM needed maintenance after 3 years of constant use. I’m gambling strain waves will go a lot longer due to a simpler design and less concentrated forces.
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GTom avatar
GTom avatar
Correct, traditional gears need regreasing, cleaning every other year, maybe the odd belt replacement. BTW latter might be needed for the HAE mounts too in a few years down the road, hopefully they are standard issue parts.

For this one I've set a sub $1k budget as this won't be my primary mount: it shouldn't break the bank if falls off a rock, gets confiscated by a 3rd world country's customs, or stolen from a hotel room. Also, obviously from the travel mount nature it only needs to carry an airline portable scope, nothing larger. Currently I own three that qualify: a 90/600 triplet, a Nikon 2.8/300telephoto (I'll revisit the dslr market if I could upgrade that to 2.8/400 anytime soon) and a Quattro 150p. Total useful weight in all cases around 7kg/16lbs. These are all fine for a CEM26. However, never held the mount head in my hands, no idea about real life airline portability. Re airline portability: mount head definitely comes on board in the small carryon (I can take one small and one "large" bag onboard), counterweight, tripod can go in the checked luggage.
andrea tasselli avatar
andrea tasselli avatar
Correct, traditional gears need regreasing, cleaning every other year, maybe the odd belt replacement. BTW latter might be needed for the HAE mounts too in a few years down the road, hopefully they are standard issue parts.


I very much don't think so. Maybe every 10 years. And these gears don't wear down, period.
Bob Lockwood avatar
Bob Lockwood avatar
andrea tasselli:
Correct, traditional gears need regreasing, cleaning every other year, maybe the odd belt replacement. BTW latter might be needed for the HAE mounts too in a few years down the road, hopefully they are standard issue parts.


I very much don't think so. Maybe every 10 years. And these gears don't wear down, period.

I second Andrea, period.
Dave Rust avatar
Dave Rust avatar
The CEM40 needed repair after 3 years. Ioptron replaced the worm gear and rotated the RA ring gear to the unworn side. Everything was regreased. The internal electronics were upgraded along the way. 

Performance had degraded steadily for a few months before the unit was shipped in. After repair, the unit functioned even better than new. Roger, my ioptron contact in Boston, had evaluated the issue and his team completed the work in speedy fashion. He said the worm gear had worn unevenly and thusly wore on the ring gear. There was no obvious sign of damage. 

Roger also suggested that deviation from spec can be expected after 3-4 years. 

However, one can’t rule out that the mount was somehow mishandled at my place. It’s possible the scope was bumped or moved by others and the mount experienced stress. I’m in a single family home, so visitors to my garage are few, but this can’t be ruled out.
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GTom avatar
GTom avatar
Dave Rust:
The CEM40 needed repair after 3 years. Ioptron replaced the worm gear and rotated the RA ring gear to the unworn side. Everything was regreased. The internal electronics were upgraded along the way. 

Performance had degraded steadily for a few months before the unit was shipped in. After repair, the unit functioned even better than new. Roger, my ioptron contact in Boston, had evaluated the issue and his team completed the work in speedy fashion. He said the worm gear had worn unevenly and thusly wore on the ring gear. There was no obvious sign of damage. 

Roger also suggested that deviation from spec can be expected after 3-4 years. 

However, one can’t rule out that the mount was somehow mishandled at my place. It’s possible the scope was bumped or moved by others and the mount experienced stress. I’m in a single family home, so visitors to my garage are few, but this can’t be ruled out.

Unless you used the mount every single day moving a scope close to the payload limit, 3 years sounds a little early for significant degradation of a brass gear provided it was always well balanced and taken good care of.
Dave Rust avatar
Dave Rust avatar
The mount was used pretty often…three times a week for long periods. And keep in mind there might have been a quality control issue to begin with. Weight was indeed within spec but on the heavy side. Mounted was a Celestron EDGE 925 and accessories coming in at a total of 30 pounds. Mount is rated for 40 lbs…,so 75% of its capacity.
SkyHoinar avatar
SkyHoinar avatar
I air traveled with my equipment few times in the last two years during the summer holidays and it was fine. I have an iOptron HEM27 mount paired with a 80mm APO, so a reasonably portable setup (I really had this in mind when I purchased it, having that in the area I am living I do not have too many nights with clean sky over the year).
Even before I air traveled twice with my old ZEQ25 mount, which was a bit heavier than the HEM27, but it was also fine to take it on the plane after all.
I think the new strain waves mounts were designed with portability in mind and they are more suitable for (air) travel; the good point with them is that you do not need to carry a counterweight, which for ZEQ25 almost doubles the weight, not to mention the tripod which in the case of HEM27 is a carbon fiber one, very lightweight and it can be easily disassembled to fit into a small cabin baggage.
Performance wise between ZEQ25 and HEM27, at least in my experience, it's like day and night.
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