AM5 VS HEM27

[peabrain]

i am currently planning an upgrade from my skyguider pro, and i have been looking at the HEM27 and AM5.
the main requirement is small and "compact", since i travel to my location by motorcycle.
and later plan to go to about 800mm FL max 1000.

IF ignoring the price and brand, they otherwise seem close on paper specs.

if we go by specs alone which one would you suggest, the AM5 or the HEM27 with ipolar.

[The Admiral]

This is a bit difficult to answer as neither mount has any real pedigree to refer to, though the AM5 is starting to be delivered (mine on Monday ), so we are starting to get real experience coming through. I'm not sure just how much real information is available for the HEM27. The ZWO Facebook site for the mount has a few user experiences from the early testers, and a production PE curve, so is probably worth a visit. Have you seen this video?

I shall be using mine with the ASIAir, so has the benefit of being of the same brand, and hopefully, they'll play together nicely. That will also mean I don't need an iPolar, as I can do PA through the ASIAir. Currently, the iPolar requires a laptop to use, but my understanding is that iOptron are working on a tablet version, though how far advanced they are I wouldn't like to say. How important the fact that it is a hybrid drive is unknown. What focal length do you intend to use? A broad statement is that long focal length scopes are less suitable for harmonic drives on account of the level of PE.

Sorry, not sure that I have pointed you in the right direction.

Ian

Edited July 2, 2022 by The Admiral

[peabrain]

thx for the input
ATM im shooting a redcat 51 with either my asi533mm or nikon z7ii, and plan to incremental go up to max 1000mm. (next scope will be 500-650mm iguess)
currently i have a tablet windows surface pro with me so no issue there, and i plan to use the bluetooth goto function and guide via the tablet.

the northern danish skies are not the best so super high precision i dont think would matter to much up to that FL.
 

[Shimrod]

37 minutes ago, peabrain said:

thx for the input
ATM im shooting a redcat 51 with either my asi533mm or nikon z7ii, and plan to incremental go up to max 1000mm. (next scope will be 500-650mm iguess)
currently i have a tablet windows surface pro with me so no issue there, and i plan to use the bluetooth goto function and guide via the tablet.

the northern danish skies are not the best so super high precision i dont think would matter to much up to that FL.
 

I am very interested in the new wave of harmonic drive mounts, but I'm sticking with my current gear for at least a couple of years to see reviews and also what turns up from the likes of Celestron and Skywatcher.

If I had to choose between one of the two now, I would probably go with the Ioptron simply because they have a history of building mounts, and the AM5 is (as far as I know) the first mount built by ZWO. If there any teething issues I'd expect them to be more likely in the ZWO model.

[peabrain]

thx for the input
you are right about them being new, and there will be some teething issues.
But from what i gather about them as companies as of late, is that ioptron have been harder to get into contact with. and have been reading about quiet a few sending their mount back since there are some QC issues.
have seen lees of that from ZWO, but as you say it is their first mount and bound to have a few niggles.

as far a spec go they are close and by oct there may be more review data available.

and atm im just trying to figure out how much to budget etc for when the time comes.

[Blueocean]

The FAQ of HEM27 at ioptron has a comparison of HEM27 to AM5 and RST-135. Cable management and power off brake are deal breaker for me.

https://www.ioptron.com/Articles.asp?ID=346

[knobby]

These snippets are thought provoking ...

 

 

The PEC really intrigues me 🙂

And I'd love to see the 15lb payload version in August.

[The Admiral]

1 hour ago, knobby said:

These snippets are thought provoking ...

 

 

The PEC really intrigues me 🙂

And I'd love to see the 15lb payload version in August.

But note that ZWO selects it's harmonic drives to be within a specified PE (40 arc.sec total).

Ian

[knobby]

Yep, yours looks very promising Ian.

[The Admiral]

49 minutes ago, knobby said:

Yep, yours looks very promising Ian.

Thanks knobby, but until the stats come in I can't be sure, even though in my water I feel it will come good 😀. I think if one is very demanding over performance then these harmonic drives, of whatever manufacture, are most likely not to satisfy, but for fairly wide-field applications there is much to like. I guess those with encoders might be a different story, at a price!

Ian

Ian

[knobby]

FLO have sold 1 of their 7 HEM27 mounts ... Hopefully whoever bought it is lucky and it's amazing 🤞🏻

Edited July 17, 2022 by knobby
Typo

[mathieucarbou]

Also to consider:

- Stocks and sells: AM5 mounts are selling like pancakes and are nowhere in stock. HEM27 mounts are in stock and not selling as much

- Support and Community: I am following both FB groups. ZWO clearly stands behind their products. When a problem appears (we saw that with the oil leak), they fix it and own the mistake. The support team and even their devs are answering on the group. They are involving also people in beta testing. I have an iOptron mount and always had quicker (and more relevant) answers from iOptron with emails. ZWO though has a far better community on FB and forums and it is really easy to reach the support team. iOptron clearly lacks a good community and marketing team.

- Risk: both companies are new in terms of harmonic mounts... I don't see iOptron as a less risk factor than ZWO. Also, ZWO is a far superior software company than iOptron is.

- Technology: ZWO went with 2 harmonic drives (RA and DEC) while iOptron went with 1 harmonic drive (RA) and belt drive (DEC), plus some EC versions with sensors, which is not dumb IMO. But considering the final products and specs, I find the HEM mounts really expensive compared to an AM5.

- Testing & Review: far more people are testing and reviewing the AM5 mounts so even if they lack some features or have some drawbacks, the fact that there are less unknowns in those mounts can lead people to buy more of them.

- Specs: I am not impressed with the HEM FAQ. it looks like I am reading a paper to defend the design of the HEM. And what I don't like is that some arguments are made without proof, we just need to be ok with the fact that iOptron "doesn't believe" in such things. I don't throw 2 grands on a mount because a company has some unsupported beliefs, when ZWO team at the opposite explains in technical terms why they did that and how it works. Plenty of info on the website, groups and forums. In the FAQ, the screenshot at the bottom is misleading. It shows an EC version of the mount but guided at 5 seconds. What's the point ? To see the real perfs of the mounts,  we would like to see a HEM guided at a higher frequency (0.5s or 1s) which is typical for harmonic mounts. And also a graph of the EC version unguided to see how the real-time EC works with sensors. None of them are shown. Also, harmonic drives seem to come from nearly the same factori(es). Like iOptron said in their FAQ, they should have the same behaviour. Except that ZWO made a deal to test them and ensure those within ZWO specs will be in ZWO mounts...

- Period and tracking error rate: The period is not the same: AM5 is 432s, HEM27 360s and HEM44 270s. Regardless of the drive type, the longer period the better. Even if a period with a longer period could lead to more absolute diff (errors) in arcs, what is important is not how big the error can be (amplitude) but how quick the error arrive (steep): so simply if the curve contains steep intervals or not. Dividing the length of the steepest interval by its duration gives the limit for the mount in arc-sec. So the longer the period, the more chance to get low inaccuracy rates. A curve that is having a higher frequency will have steeper ups and downs. So the HEM44 mounts I guess will definitely need to be guided at high frequencies. On ZWO group, we saw many users with good PE reports being able to do exposures of 10-15min unguided (with a 400mm FL or less of course).

- Design: this is a very personal opinion, but I like the AM5 design more. They also have a very good ecosystem and quick release system with their tripod and pier.

- Software: considering that these mounts now tend to be less "cable-operated" but more and more driven by technology, software and apps, ZWO has a strong developper team, while iOptron apps are really ugly and not on all systems and devices. I have more confidence for example in doing EAA with the Am5 mount and the ZWO AM5 app (which has an included planetarium).
 

So to me, there are too many uncertainties and hidden facts in HEM mounts that, IMO, make them expensive and a risk far more than AM5 mounts. And I have an CEM40 🙂 So I don't dislike iOptron mounts. It's just that it seems to me they have rushed out the HEM mounts and didn't take the time to properly build a community, have proper tests, reviews, better specs and arguments and technical explanations of their design to make people attracted in them.

That's the thinking process I had when I've made my decision.

Edited September 9, 2022 by mathieucarbou

[peabrain]

sorry for the late responce, ordered the HEM27 earlier this week.
found a deal tha saved me a bit getting the ioptron CF tripod for a cheaper price also.

i plan to find a good template and try and review it kinda. might share it here if some one is interested.

[Shimrod]

15 hours ago, peabrain said:

sorry for the late responce, ordered the HEM27 earlier this week.
found a deal tha saved me a bit getting the ioptron CF tripod for a cheaper price also.

i plan to find a good template and try and review it kinda. might share it here if some one is interested.

What persuaded you to go for the HEM27? You had some concerns about QC issues and the suggestion from others in the thread indicated a preference for the AM5.

[knobby]

I bought the HEM27 recently, choice determined by available funds and a @FLO offer at the right time ...

I'm not really sure yet but I think I like it 🤞🏻

I'm still trying different guide parameters and learning the Ioptron commander side of things.

Attached a guide log from 16th sept. No imaging, just playing with different settings, guide assistant runs etc.

Pe seems to be about 40 peak to peak if I've read it correctly.PHD2_GuideLog_2022-09-16_203828.txt

 

[peabrain]

the price at the shop on hem27 was a little under other, and jumping back and fort about both being new mounts.
i decided to gamble on the cheaper option this time, and being used to the ipolar also kinda gave me an nudge.

after reading about ZWO kinda "forcing" users to only use their products together, gave me a feel that there might be some ecosystem requirements i dont wanna bother with.
Eg the asair mainly only works with ZWO devises.

now i just need to figure out how to setup it up in PHD2 and wait for it to arrive.

[knobby]

It's easy in phd2, just connect the usb to the handset, run Ioptron commander, find the com port from Windows device manager , connect then run new profile wizard.

A little foible I noticed is that the mount mount track until you've done an alignment unlike skywatchers.

[peabrain]

normaly i balance then level then do my PA (although sgp needed a testspin) then i frame then start selecting guide star in PHD2 and let it cali from there.

but might need to start the first HEM session a bit before AP dark to have a go with how it is works with PHD2 on what it is in the dropdown menu selection.

 

[peabrain]

does any one here know the basic of gettign PHD2 setup for the HEM27.?

[baggywrinkle]

I have the AM5 and will control via the ASIair. Hoping to give it a proper outing at Kelling this week...Will use with the 52 mm Cat and hopefully see how it does with an 8"  Edge.

[The Admiral]

On 18/09/2022 at 11:06, peabrain said:

about ZWO kinda "forcing" users to only use their products together,

That's their strategy, but as affective as they are with their own products, it's up to the potential purchaser to decide if that's something they can accept. If not, then there are other similar products/solutions on the market. In theory, by restricting application, they can at least ensure that the product will work properly.

Ian

[peabrain]

11 hours ago, baggywrinkle said:

I have the AM5 and will control via the ASIair. Hoping to give it a proper outing at Kelling this week...Will use with the 52 mm Cat and hopefully see how it does with an 8"  Edge.

sounds like you are heading for a fun outing 😁

 

[baggywrinkle]

9 hours ago, peabrain said:

sounds like you are heading for a fun outing 😁

 

However the weather forecast is not very optimistic..

[peabrain]

same here since i have an m31 and MW shot planned, seller informed they might have a shipment mid this week so hope it might be here start next week.

think my first outing would be a test to see max sub times and test on a simple target like 7sisters.