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Tracking and guiding accuracy

iOptron HAE69C EC Harmonic Mount Equatorial Mount
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Tobiasz avatar
Tobiasz avatar
Hello,

I like the idea of high resolution encoders in strain wave mounts the reduce the bad periodic error. I searched for information and reviews about this mount and only found one review from Dark Sky Geek, which was disappointing. The mount he reviewed had large backlash and a peak to peak periodic error of 30" in RA.

But this is at a sample size of one and that's why I wanted to open the topic here.

I have the following questions for people that OWN the mount:

What is your guiding accuracy? At which sampling/focal length and payload?

Did you do a frequency analysis in PHD2? Whats your PE with the encoders?

How much is your backlash?

With its price and payload with CW (36kg) it might be still an attractive option, but if the numbers don't match the price I think there are better options out there.

I am looking forward to your feedback!

CS
Tobi
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Ashraf AbuSara avatar
Ashraf AbuSara avatar
Hello Tobi.

I have owned and used the HAE69ec now probably more than most (I also have the HAE69c without the encoder). I have used it for more than a year.  I watched Dark Sky Geek's review, and frankly the one thing that bothered me with that review is he really never bothered to correct his PA because it was "not as straight forward" as his CEM70 or CEM60. I agree with him that the PA process can be a little finnicky, but I never had trouble getting my PA down to under 1' in my backyard in less than 5 minutes, once I got used to its behavior. So it puts some of his other tests after that in question if his PA was never under 40' through out the testing.

I have put multiple scopes on it, most the AG Optical FA12 (55lb payload) with a sampling of  and now I have it housed remotely with a TOA-130 on it, and it has been imaging almost every night. 

AG Optical was sampled at 0.49"/px, and the TOA-130 is sampled at 0.783"/px.
What is your guiding accuracy? At which sampling/focal length and payload?


Guiding accuracy on average is 0.4-0.45". Often it is under 0.4" under good seeing conditions for targets slightly farther away from the celestial equator. This has held true for both the TOA-130 and the AG Optical FA12. 
Did you do a frequency analysis in PHD2? Whats your PE with the encoders?

To be clear, there is only one encoder on the RA axis, and it is a "high precision encoder" not an "absolute encoder". The are no encoders on the DEC axis, and it really does not need it. When measuring PE using guiding assistant, I find a native PE value in one period about 3” peak-peak (or +/-1.5”) .


How much is your backlash?

I have tested Backlash in PHD2, and I got some wildly variable results, anywhere from 100ms to 2000ms. When I applied the Backlash compensation settings in PHD2, especially if I used the higher recommendations that are more than 700ms, the guiding actually significantly worsens, and demonstrates that there is significant "overcompensation". I have been guiding without any backlash compensation and it worked much better. I think in reality the backlash is small, but there is something in that test that is producing erratic results. I haven't checked this in a very long time. I might give it another try. 

Bottom line, this mount is a step above any other non-encoder based harmonic mounts. It retains the benefits of SWG mounts of being excellent Payload / Mount weight ratio, and the need for CW is optional. Personally I kept using a counterweight on it anyway to improve wind resistance, but obviously no balancing is needed.

Don't expect performance similar to a Mach 2 or a 10micron with absolute encoders. But it has performed well out of the box for me. 

In terms of reliability, I have had one issue with the mount. The mainboard failed and it had to be replaced under warranty. iOptron was quick to respond and fix it, and the turnaround was about 3 weeks. I haven't had any issues since. 

Hope that helps.
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Tobiasz avatar
Tobiasz avatar
Hi Ashraf!

thank you very much for your in-depth feedback about your mount. I appreciate it very much and this was exactly what I searched for - first hand experience and data.
[...]never bothered to correct his PA[...]

Indeed, this was one of the points that raised my eyebrow during the video and also one of the reasons why I posted in the equipment forum of that particular mount.
Guiding accuracy on average is 0.4-0.45". Often it is under 0.4" under good seeing conditions for targets slightly farther away from the celestial equator. This has held true for both the TOA-130 and the AG Optical FA12.

Excellent results, which I kind of expected from that mount. You did not have a permanent setup with a pier right? 
When measuring PE using guiding assistant, I find a native PE value in one period about 3” peak-peak (or +/-1.5”) .

Fantastic, with such a small PE the mount is definetly an option for very high focal length imaging. 
Don't expect performance similar to a Mach 2 or a 10micron with absolute encoders. But it has performed well out of the box for me.

Yes, you are right. What is so appealing to me is the combination of high mobility and RA precision of the mount. As far as I can tell this is an unqiue selling point that only iOptron has. This is especially important for mobile astrophotographers (like me).
In terms of reliability, I have had one issue with the mount. The mainboard failed and it had to be replaced under warranty. iOptron was quick to respond and fix it, and the turnaround was about 3 weeks. I haven't had any issues since.

Good to know.

Well, thank you very much for your feedback and (unfortunately) that takes me back right on track regarding the mount, because it is a very attractive option for mobile astrophotographers that have to travel to dark sites but still want to shoot with heavy payloads and high focal lengths. I have a WD-20, which is working very well but I can't get rid of that itch that let's me think the HAE69CEC might be a more future proof upgrade. I am shooting at 2000mm and sometimes it can be iffy with +-30" PE and not so perfect conditions.

Regards
Tobi
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Rick Krejci avatar
Rick Krejci avatar
I had the HAE69EC  for about 6 months.    It was quite a good mount, but I do agree the PA was quite finicky especially with heavy loads.    Since the mount+scope is not in balance on the pier, when you loosen the adjustment screws, it shifts in elevation.    You can work around this once you come to know and compensate for the behavior (adjust az first, tighten and then adjust el).   It worked well with ASIAir, which was a pretty slick system with low learning curve.

I really didn't like the fact that there are no clutches.    If something messes up and the scope hits the pier, the high torque and no clutch can cause serious damage.

The USB on the mount was very flaky.  IOptron send a new USB chip and that addressed it,

Guiding could be quite good, but I was getting occasional spikes at regular intervals.     It changed as the weight shifted while tracking…would be great for an hour or 2 and then start spiking several arcseconds every few minutes, even unguided.   I suspect it was related to gear meshing.    I dealt with IOptron support for several months.    They usually took between a day and 2 weeks to respond which was very frustrating.    Eventually I sent the mount to IOPtron for adjustment and it seemed to work better after that.

I ended up buying a used Mach2 GEM mount with absolute encoders.     It's a lot more expensive (less than double comparing used Mach2 and new HAE69EC) and heavy for sure, but it's light-years ahead in quality and workmanship.    And I can sell it for at least what I paid for it, whereas I took a big hit selling the HAE69EC.  I can loosen the clutches and move the scope around and it always knows where it's pointing.    The polar alignment scope gets me within 1' in a minute and the adjustments are easy and accurate.   There is no Periodic error due to the encoders.   You can model the dec arc of your target and track unguided for 10s of minutes no problem, but I use subs between 1-3 minutes and it handles those unguided no problem without modeling.   It did not play well with ASIAIR, so I got a small Mele micro PC and learned to use Nina…no regrets there at all.  It just does what it's supposed to do and is transparent.   Support from Astro-Physics is incredible.

I had both mounts on an IOptron tri-pier which is pretty good.    With my 10" Newt, the whole HAE69EC, tri-pier and 10" newt was too heavy to carry out each night so I got a JMI Wheeley bar to wheel it from the garage to driveway.    I use the same thing for my Mach 2, so weight wasn't much of an issue for me.

But if you want a more portable and capable mount, the HAE69EC is quite nice.   If I had to carry it around rather than wheeling it out, I'd probably still have it.
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