HARMONIC DRIVE Mounts Showdown! HEM27 vs. AM5 

The reason you are able to work full time from your channel is because you are excellent at your objective. This review was second to none. Thanks again.

Another excellent and thorough review. Thanks for doing all the work needed to put three mounts to the test as equally as possible. Well done!

Very nice. I always appreciate field testing of gears and not just reading specs. Good job

I've had an AM5 for a couple of weeks now, and I'm very pleased with it. The portability is great, and a hand controller would just get in the way. I have an ASIAir Plus, and I don't even plug in the supplied joystick. I started with a Sky-Watcher AZ-GTi a year ago, align with a laptop/ASIAir+, and have never even used a polar scope, so it was a natural transition for me.

You really know how to review stuff, amazing job covering all the features!

Again a very thorough comparison. And what a work you have put into it. Experience really shows compared to how I struggle to get everything right for just one setup. LOL. Thanks for sharing and showing how it needs to be done.

Thank you Nico like always the details in the video are above and beyond. Thanks for your efforts. Clear Skies. This video helped me in deciding my next upgrade!

As far as I know your review is the only side by side comparison. Very helpful.

Awesome review! I own a HEM27EC and as for the polar alignment, I pretty much just hand tightened the lock screws and I don't ever have to touch them again as you can still adjust the ALT/AZ and use the hex key inserted into the knobs for more more torque. It doesn't move through the night either. As for guiding, I had issues at first but after I figure out how to reset the iPolar and have the mount auto-calibrate the RA axis (EC mount) I am getting usually around .5 arc second average. The DEC axis is the typical iOptron backlash free worm drive but I don't know why it is called that because I always have backlash even on my CEM26 so you just have to use the guiding assistant to figure out the backlash or just dither in RA. I so far am up to 30lbs on the mount and found out the hard way that I needed a counterweight. The strain wave is powerful but if you park and you have over 29lbs the RA starts to back drive not good! I also was starting to have tracking problems. Added the 5kg counterweight and no more back driving, tracking issues, or odd popping noises 😳Thanks again for the through review! Clear Skies and Happy New Year!

Nico, thanks for taking your time for evaluating these mounts, I’m planing to get one, waited in pre-order more than 8 months for AM5 and cancelled because is not serious, I still planning to buy one, thanks for honest review, will be nice to see a test without guiding to see tolerance.

By far the best review I have seen for these mounts !!!!!!!! Thank you !!!

This was really REALLY well-done! Very thorough and easy to understand. Thank you and I’ll be joining your Patreon!

Wonderful review. Thanks Nico. I am getting the same performance with the EQ6R and the AM5. I would just say that the AM5, handling a small telescope, as a RedCat, gives incredible results. Consistent total error below 0.45.

Thanks heaps for the very practical revelations. A great comparison very informative for panning future upgrades.

Just astonishing that what used to be clock drives (lesser quality) or worm gears (higher quality) when I started the hobby in the 1960s, has advanced to digital stepper motors and belt drives, and now harmonic drives. All the while the prices have remained relatively constant in real dollars.

Thanks for your great presentation. Absolutely brilliant and clarifying. I love my AM5. All the best, clear skies and shine on from Chile, Cluster One Observatory.

Great comparison review. I have to say that I loved seeing a little rust on the EQ6... such character :) These harmonic drive mounts look interesting.. especially for the portability. I think for a semi permanent location like my backyard.. I'd prefer to have the heavier EQ6 though. CS!

Thanks so much for the review - very helpful!

Thank for this video. I was thinking about upgrading merely because of the size and portability

Hi Nico! Very good review, much needed for my planning. Have a Happy Holiday and Happy New Year!

Thank you Nico. Your comparison videos are really scientific. I guess the only difference is in the long-term wear of the gears, where the harmonic drive might perform better.

Awesome as always!

Nico, another superb review/comparison; thanks!

Thanks for the comprehensive comparison. I am actually looking for a second mount to optimize my sparse clear sky hours. I have been leaning to the EQ6-R, which was my original choice before I purchased a GEM45G, but opted for the shortest back order time. If I had to pick a winner from the video, it is clearly...flying unicorn tie-dye!

Thanks, your videos and tutorials are the best in my opinion due to the easy and detailed way that you explain things. Thanks

Great review! Thanks for spending the time to make such a thorough review. Now I have more EQ to drool over. :)

Great in depth review! Wishing you all the best for the next year and good luck to you in your new full time job :-) Clear Skies!

Outstanding review. This is comprehensive and useful information. Well done!

Im new into astro photography and put myself on a 4 month wait to buy anything before i pulled the trigger on anything you and @astrobiscuit have helped me huge amount, getting into the game.

This video is perfect! Exactly what i was looking for, this new mount tech is great!!

Wow. Excellent review. Thanks very much.

Excellent review. Thank you.

Superb piece of work.... You're one of the best astro folks on RU-vid. Thanks for a great job.

Excellent review of mounts and performance.

Great review and happy to see one comparning three mounts, with different payloads. I've had my AM5 for a few months now and love it. I was a Celestron AVX user, and looking at getting the EQ6R when the AM5 was released. I'm getting older (a bit!) and I have to move my equipment in and out of the house a lot, so was willing to take the risk of the AM5 preorder. So glad I did! Thanks again for the review :)

Great review

Great review. I'm an EQ6R guy myself, and my back has had enough.... :) AM5 looks good, thanks again for the valuable info

thanks for the comparison, it would be an interesting to see if the two Harmonic drive mounts tested with a C8 next

Love the curtain reveal! I wish I could've seen more of the rho complex. Great video tho!

thank you so much! this is valuable

Love the comprehensive review. iOptron made good mounts, but the sheer number of knobs and tools needed to fiddle around during polar alignment makes using it a bit of a hassle. My thought is that, unless you are used to iOptron mounts, with the Allen wrench that can drop accidentally, get a plastic mat or even a thin plastic table cloth that is white and stick it beneath the tripod legs and spread it flat - so that if the wrench slipped from your hands it won't be lost in the grass or dirt in the dark. Regarding the EQ6-R mount AC plug, the same kind of 12mm aviation plug is used in AZEQ5, I made one from 12mm aviation plugs I ordered so that it can use 12V DC output from my power box instead of dangling with a power brick or using a cigarettes' light plug.

Ok... well thanks Nico ;) I have an AM5 review video in the works, but you now made me realize I am nowhere near finished with that video. Hahaha. I'll do mine in Dutch primarily, but your video made it clear I have skipped a few very important things to share.

Thank you for this review. It helped me.

Very nice review.

Great job being first to put together such a great review. Really helped me make a decision here

Great video!!! Thank you!! I am surprised you didn't run all 6 tests on the same night !?!? 😲🤣 I am sure you could have managed 6 mount assemble and dissemble no problem 😉 I'll remember this video when I am annoyed by dissembling my mount after my session.💪

This is the best review of these mounts I've seen! Thanks! One thing I'm still curious about is what they looked like when cabled up. Cable management is a pain with my current set up (HEQ5).

You read my mind! I was looking for a video like this just a few days back. Thanks a lot. I am considering to buy a harmonic mount because I am planning a trip to Atacama and I don't want to bring my heave EQ6-R. One thing that I was looking into you video but there was no comment about it is the compatibility of the AM5 with NINA. I don't want to use ASIAIR and I heard that the AM5 cannot handle two different "external" softwares at the same time, like NINA and PHD2. Amazing video, thanks again!

13:58 My Pegasus power box came with both 5x2.1 and 5x2.5 cables. Which was a nice surprise. I really like that all the cables on the HEM27 go into the back, out of the way. Also, my hand controller came with a button battery installed (maybe the supplier added it?). I have my NUC mounted on the tripod behind the mount connections, using a 3D printed bracket, the power box is next to it, on another 3D printed bracket, which feeds the mount and the NUC, plus the two heaters, using a 12v 10a power supply. The mount feeds power to my IMX 571 via it's 12v 3a output on the DEC axis, plus the ZWO focuser is powered and controlled via the mount USB2 connection on the DEC axis. I then run the guide cam USB2, IMX571 USB3, and the two heater cables, down to the NUC and the power box, in one nice tidy group, bound together with some 3D printed cable tidies. The focuser USB2 comes out of the back of the mount and straight into the NUC. I could run the guide cam and focuser through the IMX571, which has a USB2 hub, but that would only eliminate one USB cable and would potentially slow down my USB3 data speed. I could get a USB2 hub and run them both through the USB2 on the DEC but... meh... why bother? If the mount had USB3 I could run everything together through the mount and eliminate two of the cables. But it was not to be.

I was a member of PPA many years ago when I had my photography business. I knew some of my friends who were members and had cause to use their insurance, and it saved them $$$$$.

And Nico drew his weapon : the 130PHQ ! A dream scope. It seems that payload isn't a problem. I'm reassured : my 160 mm scope in the procces of being manufactured will be fine ( 14Kg with collars and dovetail ). Thank you Nico for this very informative video.

Thanks!

That's cool. I just learned about harmon drives last year, on a couple of other maker and robot oriented channels.

Good review/overview. Thanks! I have the HEM27 and I’ve grown to really like it. At first I was also put off by needing the little allen key wrench for alt/az adjustments, but I’ve gotten used to it. It is a pain when you drop it though. I was also surprised by the inability to bypass the hand controller. Honestly, you pretty much called out all of my annoyances with the mount when I first got it. What I do like is the pass through cabling, and compact size. I also own a RST-135 which like the AM5 has cables and power plug into the declination, and I really don’t like having my power plugged into a moving part with an unsecured plug. I also like that I can throw any of my small to midsized telescopes on it without worrying about dealing with a counterweight.

I bought the HEM27A and the carbon fiber tripod to go with a petzval type scope for a checked bag airplane friendly travel kit. That thing is amazingly lightweight.

I look foward to a full evaluation of the Ioptron HAE29 which uses the harmonic drive for both RA and DEC.

One part I would like Nico consider to test is to keep the OTA setup weight within both HEM27A/AM5 maximum payload without counterweight and use a long OTA to compare with the short StellaVue OTA test. The second set of tests changed more than two variables (OTA weight, FL, camera and the counter weight)

Excellent review as always. I think that many, me first and foremost, are also interested in knowing the settings you would give on Asiair plus for harmonic frames: exposure time (apart from 0.5 sec for the iOptron), calibration step, Max Dec and Max RA duration, RA and Dec Aggr with both scopes you used for the test and viewing conditions during your test. Thank you very much

The fact that the HEM27 requires an allen key for mechanical adjustments just frustrates me. It reminds me of when Celestron came out with the CGX and decided to engineer the mount around the use of an allen key. It just feels like a downgrade from previous workhorse mounts like the CGEM and AVX. Appreciate how in depth this review was, fantastic video as always!

What a wonderful video mate, your methodology and presentation are a real inspiration! 😀 I've seen all of these mounts individually in person, yet nothing can prepare you for the side-by-side view, haha! It's near unfathomable that these all have the same payload capacity! I was impressed with all three, but the am5 stood out most to me in this group comparison, I'd like one of those some day. Thank you for your work in putting this together Nico, amazing work as always!

Thanks again Nico....I now own an AM5 with ZWO's "free carbon tripod" sale.

Very excellent Video . Thanks Nico !/SRK

Also, you are able to adjust the volume of the sound that AM5 makes; when set to lowest, it becomes quite silent.

I’ll stick to the EQ6R pro as that extra weight is great if there’s any wind about

Just for the record, the EQ 6R was about $1500 pre-covid times. I wonder if these mounts would cost the same if we wouldn't have this crazy inflation.

Couldn't have come at a better time

I have two Astro Physics mounts in observatory....900 and 1100 that run either a 6" APO or 11" SCT with Hyperstar. For remote imaging that is a lot of gear and weight to deal with. I recently desided to get a AM5 ZWO mount and their ASI AIR plus which will be used with a couple of refractors but not the 6"....generally 80 or 85mm APOs. If you go with the AM5 you have to use their cameras, and their autofocuser and motorized filter wheel or they won't interface with the ASI AIR plus. I don't mine that as since they developed the system they should be able to gain some financial pay back. The ASI AIR does work with many other mounts though incluiding Celestron and my AP mounts. Other than the weight the main reason to go with the AM5 is the ASI AIR plus.....it indeed takes imaging to the next level. That one box and your cell phone or tablet replace ALL your software, stacing, focusing, autoguiding, etc. are all do ne from those two pieces of equipment. The ASI air now does polar alignment by looking anywhere in the sky and doing a plate solve. An on screen view in the app shows exactly how far you are off and lets you adjust both axis easily until perfectly aligned. Main con is that they recommend to stick to a maximum focal length of around 900mm. My small refractors are fine as is a Hyperstar equiped SCT. The other huge advantage of these harmonic drives is the ease of setup. I have the mount, cameras, autoguide scope and its camera and all wiring in one assembly. The tripod is the only other piece of equipment other than a power source (I use a wheel chair battery). I can take the battery, mount, and out of my car and have it running in about 2 minutes. The ASI AIR plus has wireless operation so I can have the scope out on my patio and operate it from my nice warm kitchen (here in Michigan Winters that is nice) Finally you can also use Sky Safari to control the mount and switch to the ASI AIR app for image capture, autoguiding, stacking, etc. Although the ASI AIR plus app has its own planetarium program. There is a 10# counterweight and a short 9" counter weight bar that is used when you get over 28# load and want to carry up to 44#. I don't believe the weight is needed for balancing of the mount so much as keeping the losd from getting off to one side during tracking and toppling the whole thing over. I use a different tripod than the one WZO sells for the mount since I had it already and it is a bit heavier duty tripod. the mount uses a standard 3/8" screw common to most camera tripods.

You have to love the EQ 6R Pro. Looks like it's made out of cast offs from a cheap washing machine conglomerate operating out of a junk yard in Shenzen, with parts from a neighbouring breakers yard. One point about port positions: Ports should not be facing upwards (take note ZWO) because they will catch any condensation, rain or dew, and short out your connections. Water can also get inside the mount through the ports

Purchase a set of "uxcell 3mm Ball End Hex Key T-Handle Wrench Spanner, Metric S2 Steel 2 Pcs" off Amazong for the HEM27. There is a 3mm hex head inside both Azimuth knobs for polar alignment. you can insert these wrenches inside the knobs and have much finer control.

Excellent in-depth comparison, Nico, thank you very much! A bit disappointed that the HEM27 isn't cheaper than the others (that would have been the point of using strain wave gears for only one axis...), but glad to see that mounts are working great! I assume you used multi-star guiding in PHD2 right?

The good thing about this mount you take it easy on vacation with asiair and a tablet. I like the EQ6-R pro but that's to heavy for take on vacation. So in the future I think to buy this mount for when i go on vacation. Last February I got my 2nd scope the edge Hd8. But I miss the clear sky in the Netherlands now

Man I love your shirt!!!

I've found Alt-Az mode is great for planetary imaging, too. You don't have to worry about meridian flip, and for low-altitude planets, you can more or less keep the ADC angle constant. In Eq mode, you have to constantly rotate the ADC so that's it's horizontal vis-à-vis the horizon. The former advantage would've come in really handy to those farther east of me the other day when Mars was occulted by the moon. While I wouldn't have had a big issue here in New Mexico since the main event occurred well after meridian, for those on the east coast, the crucial main even occurred right around meridian. Obviously mounts can go past meridian, but it would've been hairy. AM5 would've worked perfectly in Alt-Az mode :)

Hi Nico first of all happy new year to you And i am a big fan of you and your videos about astrophotography i just love them.I was wondering if you could make a video about astrophotography without a motorized or tracking mount,but with a manual eq mount with a 6inch newt on it. This will help beginner astronomers like me a lot..🙂

The HEM27 lock screws can be replaced with adjustable handles. They come in many screw sizes in both metric and inch. Also different screw lengths. McMastercarr sells these as do other companies. They tend to cost anywhere from about $5 for the smaller ones to about $9 for the bigger ones. I use these in most machinery I build, and often replace locking screws on commercial machinery with them as well. This is a very interesting review. Even though I’ve been interested in astronomy since high school, living in NYC doesn’t give one the best (best, ha!) viewing conditions, so I’ve never gotten involved.

Great comparison of "old" tech and new! I really appreciate the graphs (as an engineer) and calling out the pros/cons of each mount. I personally have an Orion EQ-G (HEQ5) and have been thinking hard about replacing it with a AM5 soon. The one thing I didn't really see addressed was balancing of the scope/mount. The EQ6R is a no brainer... what about the balancing of the other two? The HEM has at least one clutch so I guess DEC balancing is pretty standard but how do you balance your scope on a strain wave setup?

I always wonder if there is a technical reason why the companies don't use fine threaded bolts for the polar alignment adjustment.

Really nice Nico, thanks! Thats great. Exactly what I was looking for. After doing my back in (again!) two weeks ago, I'm thinking again of retiring my venerable EQ6 in favour of an AM5. Glad to see confirmation that they can all take my EON 130APO and are all comparable options. I would love to know if tools are needed to attach the harmonic mounts to their tripod with/without pillar? I have a bit of a hand disfunction (so basically setup and tear down has to be something I can still manage one handed - including dismantling to pack into their box at the end of the night).

Hey Nico Can you do a video about an OTA Setup with guiding using a DSLR(bc its heavier) just under 11lb to use with the SA GTi.

I would think mounting the AM5 on a Tripier with adapter would be the best of both worlds for stability, clearance, portability and weight.😀

The HEM27 has conventional stepper Belt Drive on DEC axis. Where the HEM5 has Harmonic on Both axis. Slow Dec time recovery. Thanks Nico

Jeez, I've been thinking about getting that eq6-r pro ,but it seems to be huge. I totally understand the payload capacity and all other stuff but still .

Really interesting, and educational. I hope you get the chance to run the HAE mount to compare! With the HEM27, did you balance the declination in the first imaging? I'm very interested in the HAE43. Thank. you!

Hey, non releated question. i took 600 photos of the sky at 18mm but when i put them into deepskystacker the street lights and house lights get detected as stars i think so the whole process get thrown off and i end up with a picture which shows just red when stretched. Is there a way too fix this or do i just have to not have artificial lights in my photos.

You mention a couple of times the problems of working in the dark. That may apply to visual astronomers who have to aclimatise their eyes, but for imaging that's not necessary. I have my garden floodlit if setting up after sunset, and switch off for imaging.

Hi Nico, the other reason to use a counterweight (at least with the RST-135) is to ensure the altitude stays fixed in place with heavier OTAs. I have had it slip with an Epsilon 130D, and there are even reports of it slipping with much lighter OTAs, like an FSQ85.

What tripod did you have these mounts sitting on? I think a beefier tripod will improve guiding, especially when using the big scope.

Thank you Nico for putting this together. Did you use counterweights when you did the test with your Askar 130 and ZWO AM5?

Good review. I realize it would be a logistical nightmare, but it would be nice if you could image from all three mounts at the same time to eliminate the varying seeing conditions.

very nice analysis, thank you! Regarding the Dec-behaviour (spikes + slow damping time for the smaller load) of the HEM27: do you have balanced the dec axis? This is probably not needed for the AM5 and the RA axis, but since Dec is a traditional belt drive ...

Hopefully can find those comparison photos on your website soon

Have you ever done astro with a Dobsonian or any type of reflector telescope? I would be interested in seeing a video on that subject. Also, one that has a mount for a Canon R6.

Great thorough review and comparison video Nico, I would be curious how those lightweight mounts would perform with a little wind. Although ZWO says that 900mm is the maximum for the AM5, but you had a good result with the 1000mm Also curious how those harmonic drive mounts would perform after a few years of use, because they always have to pull/push the complete weight because they are not balanced, what do you think ?

just FYI you can definitely use an iPolar with EKOS on a raspberry pi using the V4L driver and the polar alignment assitant - we did it for quite some time but it's a pig as it shows a lot of noise when aligning and it's far easier to just use your guidescope instead.

Looks like harmonics can be placed to replace traditional goto mounts. They're light, and can carry huge payload. Imagine they release a smaller harmonic that can match a HEQ5 Pro, but the mount is lighter. They can pretty much replace small mounts like SA2i all the way up to HEQ5 Pro. Except in pricing though, because they will be more expensive lol.

Good review. Honestly a more apples to apples comparison would been with the HAE29, not the HEM27.

Many thanks for this comparison. Which guiding exposure times did you use for the different mounts?

The trouble with the Ioptron altaz locking bolts is that tightening them throws out your PA.. The 'knack' is to tighten each one slightly in turn, back and forth pushing it back to centre each time until it feels solid... Another one of ioptrons many foibles

i would love either the AM5 or the HEM27, the big reason im frustrated is the fact the AM5 with tripod is 3400 Dollars here in Europa, which is insane (HEM27 is around 3100 Dollars aswell)

So, it really comes down to the size of the mount according to me, as the guide graphs seems quite alike and has more to do with the specific circumstances during the shot. It would how ever had been interesting looking at the values in "Subframe Selector". If i would pick one, it would be the AM5 over the standard HEM but nothing beats encoders. I don't know if HEM EC versions can track without guiding but that is one thing I love with my ASA DDM.... but that one is HUGE and heavy as f**k. /Daniel