Cem70 or AM5?

Topic starter

Jul 12, 2023

Hello,
im getting back into AP and after selling all my gear a few years ago I’m trying to decide on what mount to get. I used to have an EQ6 used primarily with a C6(which I also sold). I currenty have an old etx125 OTA, an Evoguide scope, and couple of Canon Rokinon and Tamron lenses that performed well in the past for wide field and large object AP. I plan to get an edgeHD 8” at some point with a cooled camera.
I’m having trouble deciding between the AM5 and the CEM70. I know they are in a different class in terms of drive tech and load capacity but I believe both will be able to handle my current and potential future setups.
I would go with the CEM70 without thinking but where I currently live, my backyard has a limited FOV due to trees. So while I can do some basic visual observation and some planetary and general large object AP, I would likely need to take the setup to a nearby park for a better view of the sky. This is where the AM5 comes in since it’s much lighter than the CEM70 and seems to have decent specs and possibly better quality control.

Appreciate any advice!

Engaging

Björn Arnold

Jul 12, 2023

I have a CEM40 which carries my EdgeHD800 with ease and very good guiding results. Maybe an alternative/3rd option to consider?

David Nozadze

Jul 12, 2023

AM5 is an amazingly capable little mount, easy to set up, very lightweight and compact. It carries my Takahashi Epsilon 160 with ease. But, in general, it is recommended for the focal lenght below 1000 mm.

If you will use your Edge HD in Hyperstar configuration, AM5 is the way to go. At full focal lenght - I don't know…. I would still go for the AM5 and try to have very good guiding during the sessions.

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Reg Pratt

Jul 12, 2023

I will always vote to get the highest capacity mount you can. The CEM70 head is only 30lbs so its still very portable. In the future when you want a larger telescope you'll be glad you don't have to also upgrade your mount.

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Eyecon

Topic starter

Jul 12, 2023

Reg Pratt:
I will always vote to get the highest capacity mount you can. The CEM70 head is only 30lbs so it’s still very portable. In the future when you want a larger telescope you'll be glad you don't have to also upgrade your mount.

Future proofing the setup is definitely a good point and something I’m really thinking about given the cost of both mounts. The other thing that’s making me lean more towards the Cem70 is unguided accuracy vs the AM5…I know it’s great guided but as published by ZWO, has high PE. To me this means the CEM70 will allow for quicker setups for visual and wider field AP with “native” mechanical tracking without having to always having fiddle with guiding which I understand is mandatory on the AM5.

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Reg Pratt

Jul 12, 2023 · Edited: Jul 12, 2023

All harmonic drive mounts to my knowledge have higher PE than their belt/gear driven counterparts. The cem70 is a great and time proven mount though so it's a pretty safe purchase. My CEM70 has been great and hasn't required any tuning from it's factory state. Guiding also has been quite effortless. I just ran guiding assistant, applied the recommendations, and it's been solid. I also have 2 gem45 mounts that have been equally painless so I have a high opinion of iOptron.

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GergoB

Jul 12, 2023

I personally know people that got a bad AM5 then a bad replacement AM5 after that and they ended up with iOptron after 2 bad copies. Many of them have 20+ arc sec guide spikes. Assuming you get a good copy however, it won't perform in the wind as well as a Cem70. The Cem 70 has more capacity, more accurate guiding, and more space for a long OTA. The AM5 looks better and you can pick it up with 1 hand.

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Minh Lết

Jul 12, 2023

The CEM70 will shines on a permanent pier while AM5 is for mobile setup. It's just simple as that. As yourself "Will I move this frequently" if yes is the answer then go for the AM5.

andrea tasselli

Frequent contributor

Jul 12, 2023

Minh Lết:
The CEM70 will shines on a permanent pier while AM5 is for mobile setup. It's just simple as that. As yourself "Will I move this frequently" if yes is the answer then go for the AM5.

Or buy neither. Get something else.

Eyecon

Topic starter

Jul 12, 2023

andrea tasselli:
Minh Lết:
The CEM70 will shines on a permanent pier while AM5 is for mobile setup. It's just simple as that. As yourself "Will I move this frequently" if yes is the answer then go for the AM5.

Or buy neither. Get something else.

Suggestions?

Nick Grundy

Jul 12, 2023

i've got 2 CEM70's and I love them, but I don't think you want to travel with that. If your primary imaging will be in the backyard, they are a great option (good payload/weight ratio). With good guiding, you can get anywhere from .5" to .8" rms usually.

If you will need to bring your rig inside at the end of every night or travel with I'd look at the AM5 or something similar. I have a HEM44ec that I use for that purpose and travel and it does well.

The CEM will guide better, but hauling that tripod, counterweights and a 30lbs mount around costs you in back pain.

tough call. buy both and sell the one you use less ?

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andrea tasselli

Frequent contributor

Jul 12, 2023

Suggestions?

Vixen SXD2 PFL. Or the Avalon Zero if the scope is going to be a compact one.

Eyecon

Topic starter

Jul 12, 2023

Nick Grundy:
i've got 2 CEM70's and I love them, but I don't think you want to travel with that. If your primary imaging will be in the backyard, they are a great option (good payload/weight ratio). With good guiding, you can get anywhere from .5" to .8" rms usually.

If you will need to bring your rig inside at the end of every night or travel with I'd look at the AM5 or something similar. I have a HEM44ec that I use for that purpose and travel and it does well.

The CEM will guide better, but hauling that tripod, counterweights and a 30lbs mount around costs you in back pain.

tough call. buy both and sell the one you use less ?

Indeed a tough call, I'm leaning more towards the CEM just because of the lower PE unguided, mainly because of wider field AP and visual observation in addition to the weight capacity of course.

Nick Grundy

Jul 12, 2023

I researched as much as I could before I went with the CEM70. I had to upgrade from the EQ6-R when my payload got over 30lbs. (mount seemed to struggle and I was tired of carrying that beast)

the payload of 70lbs is nice because you really don't worry about it anymore. Most scopes that I can carry around aren't big enough to be an issue for it at all.

The avalon zero looks really cool, but I don't have any real knowledge or it directly.

Let me know if there's anything you are curious about on the CEM70 before you buy. Happy to share

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Eyecon

Topic starter

Jul 12, 2023

Nick Grundy:
I researched as much as I could before I went with the CEM70. I had to upgrade from the EQ6-R when my payload got over 30lbs. (mount seemed to struggle and I was tired of carrying that beast)

the payload of 70lbs is nice because you really don't worry about it anymore. Most scopes that I can carry around aren't big enough to be an issue for it at all.

The avalon zero looks really cool, but I don't have any real knowledge or it directly.

Let me know if there's anything you are curious about on the CEM70 before you buy. Happy to share

Thanks! I was looking at some pictures of the mount, is the base of the mount really open showing a portion of the circuit board?

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Ashraf AbuSara

Jul 12, 2023 · Edited: Jul 12, 2023

AM5 for me no question. 30lbs mount vs 11lb is going to make a huge difference if you are going to be carrying this around. Not sure why people are sharing stories about someone getting a bad copy or two. I am sure every product that ever existed has a similar story. The vast majority of AM5 owners are extremely satisfied with their mounts.

If you are not going to be using autoguiding then I would consider steering away from harmonic drives all together due to high PE. But there is no question that the AM5 has allowed me to image far more than I would have otherwise. I store my equipment on my second floor indoors, and carry my setup every day to my backyard. I also setup in different locations in my backyard depending on the target I shoot. I carry my Am5 attached to the PE200 and my TC40 tripod all together. Very light and easy to move around. So far the heaviest payload I have put on it is my AT130EDT with total payload after adding accessories of about 30lbs. Total guided tracking error was 0.3-.5" on routine nights.

The weight of the Am5 is not the only advantage. The fact that it is a harmonic drive means balancing is not important at all. Anything upto 13kg can be managed without a counterweight. If you are going to use something heavier then you can slap a 10lb counterweight without worrying about balancing it.

I don't think the AM5 should be relegated to "if you are traveling get it, otherwise get something else". I think it is a fine mount for any setup as long as the payload is within declared limits.

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tjm8874

Jul 13, 2023

AM5 +1, AM5 can handle 130mm APO easily and great guided accuracy.
One more option is iOptron HAE69 (this is new product) + TriPier for your future heavy scopes.

EdFromNH

Jul 13, 2023

I have an AM5 and love it as I always have to travel (no yard). If I had bought a little later I would've seriously looked at the iOptron HAE29EC because the encoder corrects for the high PE in the harmonic drive. Best of both worlds. They have a few larger models as well with the same dual strain wave and encoder arrangement.

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Dave Rust

Jul 13, 2023 · Edited: Jul 13, 2023

The AM5 looks terrific.

There's an even lighter alternative if all you need is a hand-carried travel rig. iOptron makes hybrid drives where the easier-to-guide DEC mechanism is a standard motor.

Advantages of these hybrid strain waves from iOptron is that they include a built-in iPolar PA scope. The hybrids use a conventional worm gear on the DEC axis, making the vertical chassis hollow and leaving room to feed cables through (not possible on a double strain wave). This also makes the mount less expensive.

I've placed the HEC15 in my wishlist. 6 pounds (as opposed to AM5's 11 lbs). Carbon fiber tripod: 5 pounds. My existing WO GT71 with attached accessories: 9 pounds. Makes a nice travel rig for wide field with a total weight of 20 pounds!

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Nick Grundy

Jul 13, 2023

Thanks! I was looking at some pictures of the mount, is the base of the mount really open showing a portion of the circuit board?

it's not totally closed, but there's no circuit board I can see. (just looked at mine)

MarcoPalaferri

Jul 13, 2023

I purchased the AM5 in November 2022 and it is excellent. Its portability and load capacity are unmatched. I use it with both an RC8 (around 10kg in weight) and smaller telescopes, with the ZWO tripod, and without counterweights. I am able to achieve guiding below 0.5. The build quality is outstanding, and my back thanks me. I highly recommend it, as it is my ultimate mount choice.

All the images I have uploaded are taken with the AM5. If you need any information, feel free to ask.

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Eyecon

Topic starter

Jul 13, 2023

Thank you all for the replies. The AM5 is out of stock everywhere I looked in Canada but I found a good deal on the CEM70(600cad off for the base model I was looking at). Still more expensive than the AM5 but I guess I can start with the 70 for now because I’m not only planning to do AP. Am I correct in understanding that the CEM70 will track better unguided?

daywalker

Jul 13, 2023

not necessarily but in theory it will give you more headroom in terms of payload!

Ashraf AbuSara

Jul 13, 2023

Thank you all for the replies. The AM5 is out of stock everywhere I looked in Canada but I found a good deal on the CEM70(600cad off for the base model I was looking at). Still more expensive than the AM5 but I guess I can start with the 70 for now because I’m not only planning to do AP. Am I correct in understanding that the CEM70 will track better unguided?

Yes it should. I would never use the AM5 unguided due to PE.

Yuxuan

Jul 15, 2023

Get a CEM70 and a scope buggy. Takes me 5 minutes to haul the whole thing out and polar align.

Which mount would you get if you had a similar setup?