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I got my CEM70g in November last year, I have used it a few times now. Using short focal length refractors and 150mm F5 Newtonian I have had excellent results with the guiding much better than teh resolving power of the scopes. But then I had good results with my HEQ5 also. The challenge is with my 250mm F4.8 Newtonian, I want to achieve consistent sub 0.5 arc second guiding. At the moment I can rarely achieve 0.6, its mostly 1-1.2 arc second rms. Hopefully some of my experiences will help others: USB I have a CEM70g. For several weeks I was having random problems with my laptop not detecting the mount or the ipolar/iguider cameras. It all seemed very random. But I found a solution that always works for me:
I use an old laptop so my conclusion is the drivers don't load correctly if the CEM70g is already powered. By following these steps everything has been reliable for me. If I reboot the PC and don't switch off or disconnect the CEM70 the connection problems come back. ipolar PA I have found that the ipolar v2.5 software does not work correctly - it gives bad information. PHD GA was telling me PA Error was very bad 12-70 arc minutes! I decided to use Sharpcap with the ipolar camera. It works very well, PHD GA reports less than 1 arc second error and guiding is much better. DEC performance This is one area I still have problems with. Every 2-3 minutes DEC will spike with a 2-3 arc second shift. It does not seem to be periodic. The rest of the time DEC is under 0.6 arc seconds rms. Running PHD GA several times in a night gives different DEC backlash values, varying from 250ms to 2500ms. |
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ipolar PA Did you calibrate it? |
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USB My mount was also from November. I had to send my CEM70G back in to get the USB repaired. It was always a crapshoot on which device would load. I would have 15-45 seconds to do ipolar alignment before ipolar camera connection was lost. After a 30 minutes dance of rebooting and unplugging everything every single night it would work. The mount refused to even connect through one of my computer's USB ports. After sending it back in, I haven't had any USB problems and both USB ports work on the laptop. |
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Linwood Ferguson:ipolar PA ipolar did work very well, but since upgrading it has seemed quite bad. Yes, I calibrated it several times, going through the 2-step process. Always iguider said things were good but rotating RA I could see the centre cross rotating about a different axis. Each time I calibrated it PHD GA gave me a different but large PA error report. Using Sharpcap with the ipolar camera has been very easy, quick and accurate. |
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Linwood Ferguson: I recently noticed my CEM70G is having this exact issue. I have star elongation in the RA direction, which is most severe near the Celestial equator, while the RMS error shows ~0.3". I was scratching my head, and then realized that the guide camera simply could not pick up the rapid oscillation. In live-view mode, I could direct see the oscillation, once a bit fewer than a second. Did you get the issue resolved? I read the whole thread but did not find a solution. Thanks! |
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Linwood Ferguson: In my case it was an oscillation measurable at about 1.7hz. If you use something like sharpcap on a really bright star with small ROI, you can capture video fast enough to analyze and see it at that and multiples of that harmonic. It also corresponds to the "tick" sound some people hear while tracking. This issue dates back to the early ones. Sometime (going on old memory) late in 2020 they started offering board swaps for both RA and DEC boards, initially they were doing hand fixes, swapping a part and grounding an etch to one chip, later I think they were sending newly manufactured boards. In my particular case they swapped the board, the "tick" sound got much less, and the problem got better. While it varied night to night in amplitude, originally it was around 1" or so, and after the fix maybe half that. iOptron told me no further fix was forthcoming, I returned my mount. It is really worth noting, as some will say "who can see 1 arc second", that the issue is that it is on only one axis, not random (like seeing bloat). So a 3" star that would be round becomes 4" x 3" and you notice. But since PHD2 is averaging out, you get the bloat while having a nice fractional guide RMS. I spent many nights working on video capture to convince myself what was happening, and separate it from other issues (e.g. I also had some fan vibration, which will often settle into one vibration mode and also bloat in one direction, so if you are testing this, also try it without the fan). |
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Linwood Ferguson:Linwood Ferguson: Thanks I think it is exactly what I'm having, a ~1" and ~2Hz RA oscillation that my guiding camera cannot capture. At high frame rate in live-view, the oscillation is apparent. I can also hear and feel the tick near the RA axis. Yeah, 1" is definitely significant -- it makes the 0.3" RMS guiding error I am getting moot. |
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I have detected the same oval stars on long focal length, long exposures. I contacted the reseller of my mount about getting the RA and DEC board swapped out, they then contacted Ioptron who responded the same day. They said I should send the mount serial number to tech support and I could swap boards at a discount price! So I sent my details, and I didn't get a response! |
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| If they aren't the new boards, it is worth doing. It's fairly easy, though (if I recall) one wire in the connector on the RA will likely come loose from the molex connector. At least a lot of people had it happen. You just have to fish out the pin, re-crip or solder, and put it back. |
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I have detected the same oval stars on long focal length, long exposures. I contacted the reseller of my mount about getting the RA and DEC board swapped out, they then contacted Ioptron who responded the same day. They said I should send the mount serial number to tech support and I could swap boards at a discount price! a friend of mine just noticed this too. He was able to get new boards for feee (he got his Klimt maybe in March ?) they sent the bee ones out while he still had the old ones. Just needed a $150 deposit which was refunded when he sent the old ones back. The ticking went away |
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Nick Ambrose:I have detected the same oval stars on long focal length, long exposures. I contacted the reseller of my mount about getting the RA and DEC board swapped out, they then contacted Ioptron who responded the same day. They said I should send the mount serial number to tech support and I could swap boards at a discount price! That would be great. I already emailed iOptron and am awaiting their response. |
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| Update: ioptron sent me upgraded low-emi versions of ra and dec boards for free, and the issue of fast oscillations in ra and occasional swings in dec have been eliminated. I’m very happy with the ~0.5” rms error with a ~50lbs payload! |
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I got my CEM70g in November last year, I have used it a few times now. @pharscape This is kinda late but I had the same issue with my CEM70 and found a video on balancing third axis I notice I have the same issue but only when pointing north which is where it is unbalanced anywhere else in the sky it guides very well here is the video if you are still having this issue or anyone else: https://www.youtube.com/watch?v=zmla32ksH_I |
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| Sorry if I missed it, but is there any information available about the power delivered by the USB3 ports? I am asking specifically because of the re-designed EAF motor focus by ZWO. That one now draws power from the USB port rather than via a seperate PSU. Needs about 5V, according to the documentation. |
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Hi, I do own the CEM70G, was very nervous setting it up first times, given all the criticisms on the net. But I must say, it is a beautiful mount. I am coming from a NEQ6 with a total RMS never better than 0.7 even with drift align. now with the same setup I do reach 0.3 total RMS at best without drift align! And only with like 5min polar alignment… insane! My shots have gotten way better. And the mount is working without any flaws at night…love it!  |
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Lorenzo Siciliano: I would have thought that with spring loaded worms that backlash would be next to non-existent. Is there any physical slop in the DEC axis? I have read that there were a few problems with loose shaft bearing retainers, perhaps needs more preload? |
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| @Paul Muller No, there's no slope in dec axis. I'll double check, however. I had a little improvement by doing the third axis balancing procedure. Now the dec guide seems to be better. |
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I am in the market right now and the CEM70 is top on my list. There will almost always be issues with a mass produced product that may need user, dealer or manufacturer intervention, not great but that's life unless we buy a 10 Micron or Paramount (and you still may have issues). I currently own a AZEQ6 GT mount, tracking can vary but on most nights, I can average 0.4-0.7 less the 'spikes', inherent to out-of-the-box Synta mounts. What made a World of difference was getting the DEC and RA balance exactly right. On the AZEQ6 GT, you always go East-Heavy but in an exaggerated way, not slightly East-Heavy....very East-Heavy and adjust the counter weights after a flip, works like a dream. I also always balance the DEC first while the RA is horizontal to ground (sprit level) and go slightly camera side heavy and then do RA balancing. Even after adjusting any backlash via the worm gear screws, very East-Heavy was still required. My point is that I wonder how many of these issues, despite best intentions are really just poor polar alignment or poor balancing or a combination of both. Add to this, you're seeing conditions and not so ideal PHD2 settings. After all, we are only Humans using computers, relying on software, looking through glass and mirrors at a sky in constant flux :-) Just being the Devils advocate here and not trying to discount the issues people are having (although the 'ticks' could be a worry) - Even though I want to upgrade from the AZEQ6 GT to the CEM70, the former is now giving me great and consistent results and this is due to getting the setup right despite me originally thinking that the mount was bad...the mount was not bad, I was bad but it took a while to figure that out :-) Cheers, Bill. |
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I am still happy with my CEM70G, using an OAG on my 10"F4 Newtonian and the PHD2 PPEC algo the guiding is pretty obviously sky limited, sometimes in the 0.3X" range, often in the 0.4X" range and usually in the 0.6" or better. I can get round stars at 1100mm and 20 minute exposures unless the wind interferes. When the guiding changes by 0.3" night to night with absolutely no changes to the rig it is pretty obviously not the mount limiting things. I do not balance anything like as carefully as others do. If it sits still or only moves very slowly when unlocked and started from scope level and counterweight bar level on both sides, good enough. When moved back to the home position it does not stay there. Regards the AZEQ6, I have the Orion version of that mount as well and balancing those mounts is tricky on both axes. I found when I started imaging with it that to balance it properly you have to rotate the RA until it is noticeably counterweight high to do the Dec and for the RA you need to drop the mount altitude as low as it will go. The weight of the counterweights and payload sits on the clutches otherwise and makes them drag. To make the axes move without removing that weight form the clutch discs needs them to be quite unbalanced I have found. You can move the RA to counterweights level, unlock the Dec and it just sits there, but rotate the RA a little more so it is counterweights high and the Dec comes free and runs away. |
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| I have fitted new RA and DEC boards, now my stars are round. Just waiting for clear skies to use it for more than test shots! |
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I have had problems with usb3 connections, not recognizing camera and eaf. Also lost connections during imaging, due to usb errors and no physical disconnects. After buying HQ usb3 cables the problem has resolved, I connect my nuc, and is runs smooth as it can be. No lost connections. One thing to note is that the new ZWO eaf draws power from the usb, try to connect it to the camera hub and that will solve also some issues I think. guiding with an 8 inch F6 Newtonian 28 lbs load total, guiding is usually around .5-.6 with AAP. Should be able to improve it a bit more with PHD on NUC, not tried it yet , clouds clouds and clouds lately. CEM70 to AAP works fine, as long a you connect the main usb3 cable from the mount to a USB2 port on the AAP. Overall, after getting HQ usb cables, I am happy with the mount. Only small cosmetical issue is the rust on the ioptron tri pier bolts after some humid nights that is too bad for an otherwise perfect math for my CEM70G. CS |
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Well.....yes... I bought mine 8 weeks ago. Cem70G not one night since then without an usb fail and disconnects.. Tried everything, cables, reinstalling ascom nina windows etc. Finally ioptron responded after 4 weeks and told me to open the usb hub. What I found was shocking. After opening lots of white dust like sticky residue came out. Looks like acid from a battery but there are none. Inside the mount housing also everywhere white dust particles and some rust. I have no idea what this is. Bad quality control for sure, but the origin as I am clueless. No reply from ioptron yet but this one has to be taken back. The wiring is affected and the chips are most of all partly corroded. If you have any issues , please open the usb hub where the main mount usb3 comes out, two little Allen key openings on the side. you could have the same. Will let you know what ioptron will do to make up for this. I am in shock that this can happen with qc , or better the lack of it. Cheers Dick |
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That is a shocker, I wonder if it could have gotten contaminated somehow after assembly? It is hard to fathom what a contaminant like that would be from manufacturing, particularly something that might visibly damage IC's. I have had mine apart to check board revision numbers (Before iOptron sent out new revsion motor boards, I know of peopple who have had full new board sets sent out rather than just the motor boards) and the main board was as clean as the proverbial whistle and no sign of any significant contaminants there even after several months of field use and dewy nights. |
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This is what it looks like inside.... Cem70g |
