iOptron CEM, an iterative story; CEM40 review

[@johnmheaton]

Well done for documenting these changes to the mount. I'm sure it will help a lot of current and future owners.

[@KopLamp]

Thanks. It sure was enlightening to me 😅

[@alexbell3765]

Thank you Martin for this very forensic review. I've toyed with getting a CEM40 but due to non-availability, coupled with the myriad variants has put me off to date. Thanks for describing the mount in such detail.

[@KopLamp]

Thanks. It is a wonderful mount. I am very happy with its performance.

[@whiskyexpertsvideos]

I have a CEM40EC and couldn't be more happy. I seldom do tracking anymore, at least with focal lengths below 1000mm. If polar alignment through the ASIair is very good (less than 10" combined error, which is achieveable in a few minutes), the system is perfectly doing what it should do.

[@giuseppececere9815]

Hi Martin, I recently received a new iOptron CEM40 mount and successfully assembled with the Asiair pro. I had the same problem you reported when connected the mount via the 294MC-pro. What worked great it was plugging the usb cable of the mount into an unpowered usb hub that in turn connected to the Asiair pro. Hope this helps. Clear skies!

[@KopLamp]

Yep, a hub is what apparently is needed. I use the hub in the 294MC Pro for this. Works (when using a proper USB cable). The problem I addressed was that the old mount can conveniently connected without a hub, but the new ones for some reason need one in between.

[@SterrenKijkenInDeStad]

You are welcome, I am still enjoying your CEM25P :-)

[@OlliesSpace]

Hey Martin - Wow they're really are many iterations of this mount. Thanks for the overview. It's interesting how they have gone specifically for the NUC compatibility. Cheers Ollie.

[@KopLamp]

They did, haven't they? I am curious if that NUC model would also be good for the ASIAIR plus.

[@mas5867]

@@KopLamp Your title is not descriptive enough except for users of telescopes. Was a wasted click for me. I/we hate that. At the very least something like, "Telescopes: iOptron CEM, an iterative story"

[@KopLamp]

Sorry. Is there any other use for an iOptron CEM mount other than telescopes?

[@OlliesSpace]

@@KopLamp Not that I know of Martin ......maybe they've just branched out into toasters 🤔

[@KopLamp]

🤣

[@s.l.3918]

Hi Martin, got my CEM40 yesterday. it works perfectly with the original cable provided by iOptron and I connected it directly to the ASIair+ ... the only thing tho the CEM40 only likes a USB3 and no USB2

[@KopLamp]

Happy to hear!

[@richardspiek1401]

EXCELLENT ! Was considering what after watching this video turns out to be an original version CEM40. Never knew of all these models except for EC. Now I have LOTS to think about before spending the cash. Thank you for this GREAT and through comparison. ...Rich

[@KopLamp]

Glad I could help! Curious what you eventually decide(d).

[@michael.a.covington]

I have a very early GEM45 and it is the same story -- there have been many engineering changes in rapid succession. We almost need to do what stamp collectors do, and publish checklists of varieties and distinguishing features! The GEM45 and CEM40 are of course twins internally -- same circuit boards -- at least initially.

[@KopLamp]

Well I have my ‘stamp collection’ posted in this video (and submitted as an article to CN - hope they’ll accept) 😅

[@michael.a.covington]

@@KopLamp An article for CN is exactly what I was going to suggest!

[@RussellsAstrophotography]

Great video Martin, some interesting progressions and I am sure that anyone looking to shop for a CEM 40 will find this video really helpful . It's strange that the latest versions has connection issues with the ASIAir. I'm not sure why they would have made the inclusion of a hub necessary.

[@KopLamp]

I am not sure either. I still don’t know if it is due to the firmware changes or if it is the hardware causing this. I also don’t understand how including a hub would solve it. AFAIK hubs are just dumb devices.

[@clearskiesastro1028]

You can connect the new CEM40 USB directly to the AAPlus without having to use a USB hub. I havent tested it with my older AAPro, but with the Plus no need for hubs.

[@KopLamp]

Will test that. That makes the claim that the old Pi kernel is to blame incorrect. AFAIK the AAPlus uses the same kernel as the AAPro.

[@joepremkes]

@@KopLamp The ASI Air Plus uses a Raspberry Pi Compute Module, that has no native USB port. There is probably a dedicated USB Hub chip on the motherboard that is different from a regular Raspberry Pi 3/4. Which explains the difference with the earlier ASI Air versions (and my Astroberry RPi4), and the latest ASI Air Plus

[@Ambress]

I've got an AAPlus due to arrive Sunday and will be interested to see how things change, but with the AAPro I definitely found that a USB hub was required for the CEM40 USB2 cable plus a USB FTDI serial to RJ9 cable for the hand controller. Oddly, something about the AAPro's USB ports seemed sub-standard, as using the 2 USB2 ports wouldn't support the CEM40 and hand controller connections, yet an active hub/splitter on a single USB2 port worked, as does my current solution of a passive hub/splitter on a USB3 port. I assume with your AAPlus, your hand controller still requires the USB/RJ9 adapter cable?

[@KopLamp]

​@@Ambress I used an FTDI to RJ9 cable on my CEM25p, but on the CEM40 (2019 model) I didn't require one and needed to plug it directly in the mount+AAP (or AA+). AFAIK, that RJ9 plug is only used nowadays for firmware upgrades of the handset. Speaking of which, I hardly have the handset plugged in anymore ;-). Only once, for an initial setup of the meridian flip behavior (No flip and 5 degrees after).

[@Ambress]

@@KopLamp thanks, perhaps that was because I've been using only a DSLR. I just know with my 2021 version CEM40, the AAPro did not recognize the mount until I had also connected the hand controller with USB FTDI/RJ9 cable. ....Well, surprisingly enough, as I returned here I saw yet another KZbin video where someone addressed the same problem with the CEM40, and their solution was only that a USB hub/splitter was needed, yet NOT to also host the USB FTDI/RJ9 cable as I've been doing. I just tried to control the mount without that cable, and sure enough, that worked fine! Always good to get rid of unnecessary cables. I guess I'd just seen enough on the issue I was trying to solve that I thought the FTDI cable was still needed. After all, why use a splitter for one USB connection? Why indeed...but that's just a foible of USB support on Raspberry Pi apparently, and use of a hub solves it!

[@joepremkes]

Hi Martin! I have the CEM40G, bought new in the summer of 2021. I have the same USB issue (need a hub) when I use the Raspberry Pi with Astroberry, so that doesn't seem to be related to the ASI Air specifically.

[@KopLamp]

Thanks for that piece of info. I am inclined to thinking it has to do with a firmware change they did somewhere in 2020. They also state that you’ll have to use a specific iOptron commander version, should you want to control the mount that way.

[@ASTROindi]

Thanks for emplaning the evolution of cem40 mount, I have ordered CEM40G, due for delivery in Wk4. 22. How much of guiding accuracy you have achieved on your newer CEM40 ?

[@KopLamp]

Guiding accuracy is similar - if not the same - as on the older model. With my 60/280 guidescope and an ASI120MM mini camera I achieve an RMS of around 0.6" But a better judgement are my stars. You can find results on my telescopius profile and zoom in to see the star-shapes. The last two images were with the newer CEM40.

[@kennethkirvan9478]

The latest cem 40 as of oct 2022.To connect to the asiair plus i used the usb 2(printer cable).no issues, asiair found it straight away.

[@JonnyBravo0311]

I have the original 2019 version of the CEM40 mount. No iGuider or iNuc or iEC or ... ok, it does have iPolar, which I never use :). I have everything powered by a Pegasus Pocket Powerbox Advance and controlled by a Beelink mini PC. I have exactly 1 cable running from my mount to external power - either 12V via a Jackery 500 battery or via AC/DC adapter to my house mains. The one thing I've noticed is the USB connectors on the mount itself don't seem to hold the USB cables very snugly. Thus far, it hasn't been an issue, but I would certainly feel better if those cables were held in a bit more tightly. I wish the azimuth adjustment knobs were larger. Trying to turn them to get fine adjustments, especially on cold winter nights, can be frustrating. Oh, and the knobs on the saddle... would love for those to be larger as well. I'll have to try out the hex wrench trick you use!

[@KopLamp]

I have yet to use iPolar too. Had the mount for over a year now 😅 For me the reason is that I do my Polar Alignment using the ASIAIR only 😎

[@WindyCityAstrophotography]

Great overview, Martin! I have the original CEM40 which I tried to get without iPolar, but none were available. I have actually never even used it, having always been happy with the ASIAir polar alignment. Once the weather is warm again maybe I will try it out 😀

[@KopLamp]

Same here. Never used iPolar due to the easy PA on the ASIAIR.

[@studywithme8055]

@@KopLamp Ik heb een vraagje: wat zou je aanraden de cem40 of skywatcher eq-6-r-pro? Tevens mag ik vragen waar je tweedehands telescopen vandaan haalt en waar je meestal nieuwe koopt?

[@KopLamp]

Eq6 of CEM40? Dat is een heel persoonlijke keuze denk ik. Ik had hiervoor een CEM25p en dat was denk ik de grootste reden om bij iOptron te blijven. De EQ6 is ook een heel populaire mount dus die zal ook zeker goed zijn. Vergelijk de specificaties zou ik zeggen. Ga je veel op pad met je gear dan is mogelijk het totaalgewicht van de mount een meewegende factor. Ik denk dat de CEM mounts daar een voordeel pakken. Tweedehands telescopen in Nederland vind je het makkelijkst online. Wordt lid van astroforum.nl. Facebook is ook interessant daarvoor (daar is een gelijknamige groep). De website te-les-koop.nl is ook niet te vergeten. En natuurlijk good-old Marktplaats. Kijk wel uit (zoals altijd) want er komt nog wel eens iets voorbij wat too-good-to-be-true is. Nieuw kopen kan in Nederland bij Ganymedes (Amstelveen), maar ook bij Robtics (Leidschendam) of online bij astromarket.org of teleskop-express.de

[@studywithme8055]

@@KopLamp Erg bedankt voor je snelle response, ik heb de eq6r-pro gehaald. De ioptron was net teveel geld vond ik. Een andere vraagje: welke weers app/website gebruik je? Ik gebruik clear outside maar die klopt vaak niet. Alvast bedankt voor je antwoord.

[@KopLamp]

ClearOutside baseert zich op modellen die niet erg accuraat zijn. Best is om meerdere te gebruiken. Zijn ze het allemaal eens, dan is de kans het grootst dat het klopt. De app “Weather & Radar” vind ik erg fijn. Die geeft namelijk een duidelijk beeld van de wolkendikte. Dat is de app versie van wetteronline.de

[@RazorChrist]

I actually just got a CEM25P this weekend. It was used and didn't come with the pier unfortunately. Of course, it rained this weekend, so no first light on it yet. I had a question about the clutch releases. Did yours feel like really cheap, light plastic? Mine feel like they might pop off at any moment. I was hoping there was some kind of latch that you could replace them with that feels sturdier, but so far, I haven't found anything. Otherwise, I'm super happy with the mount.

[@KopLamp]

Indeed... On the CEM25p the clutches feel a bit clumsy. But they are really effective. I had to get used a bit to releasing the wormgear first (with the silver knobs) and then release the clutch. Also tightening the wormgear and then loosening it again for 1/8th of a turn is a bit cumbersome. The successor of the CEM25p has the same clutches as my CEM40's and I really like them better.

[@JoesAstrophoto]

Informative video Martin, I'm sure it will help those looking into CM40 mounts.

[@KopLamp]

Absolutely. Thanks!

[@Nate88it]

Great comparison! I've been using the CEM40NUC with a non-NUC minipc for about 6 months now. I really enjoy using short cables with no chance of snagging as the mount slews. The mount works well with N.I.N.A. and my guiding error consistently stays below 4 arcsec. My only real complaint is that I use an iOptron focuser on my RC 8" telescope and both it and the GPS module use the same port. It would be extremely beneficial for me if the mount had a dedicated GPS port in addition to the iPort.

[@KopLamp]

By the sounds of that RC8 I am guessing you are not very mobile with your setup. In your case I would store the location in your NINA profile and skip using the GPS module.

[@Nate88it]

@@KopLamp haha unfortunately, I do have to be mobile to get dark skies. I usually just leave the GPS module on until I have finished polar alignment and all the other setup steps, then I switch to the focuser. It works, but I would rather have both plugged at once. I tried a splitter but it didn't work.

[@avt_astro206]

Interesting video Martyn!! Happy New Year🎉

[@KopLamp]

Clear New Year 😅!

[@avt_astro206]

@@KopLamp haha!! Excellent😃

[@penguin272]

thanx for the review at the right time for me. Need to replace my avx and plan a cem40 for that. a question on payload. did you try it with max load of 40lbs or what is your max recommendation?

[@KopLamp]

I need to do some maths because I don't speak lbs... so hope I am correct; The unofficial rule for telescope mounts is that with astrophotography you should not exceed half of the max payload. 50% of 40lbs = 20lbs (around 9 kg) Center balanced mounts are different though and you can exceed that. I would not go higher than 80%. Which is 32lbs (around 14kg - rounded down) My EdgeHD incl peripherals is 9kg, so I am already maxed out perhaps as officially the max payload is including the counterweights (I think). Still I get round stars at 10+ minute exposures.

[@penguin272]

@@KopLamp payload is with counterweigts? guess you're wrong as teleskop defines it as telekopweight only " Tragekraft bis 18 kg (reines Teleskopgewicht)"

[@KopLamp]

I am mistaken indeed. I saw it mentioned somewhere as including counterweights, but iOptron themselves state it is EXCLUDING. Thanks for correcting me! www.ioptron.com/product-p/c401a1.htm

[@s.l.3918]

@@KopLamp "... I don't speak lbs ..." hahaha 😂🤣😂🤣

[@clungebucket23]

Really informative video.... I have the first iteration. It took me many months to work through its niggles but i am very happy with mine... I would love to get my guiding down from 0.9 to 0.5... But at 478 FL, its not a major issue.

[@KopLamp]

I love it very much too. Same guiding numbers. I use a 60/280 guidescope. Even when imaging at 1500mm’s with my EdgeHD I get nice round stars with up to 10 minutes of exposure.

[@clungebucket23]

@@KopLamp it's easy get obsessed over total RMS. My guidescope could be improved though, asi120mm + 50x230 isnt great... The optics in the WO 50mm guidescopes are just as basic as generic unbranded ones given away with many OTAs. I might upgrade to a 60mm doublet.... Even a cheap one would be 1000% better. WO might look pretty😬? I recently added a IR/UV cut filter, no difference though. There is A LOT of movement in those mounts and at least a dozen points of flexure... I have to repeat PA after a slew. I use NINA.

[@KopLamp]

I only look at the results, not focussing that much on the numbers indeed. Flex you say? Haven’t noticed that yet.

[@AttemptingAstro]

Just got a CEM40EC with the 8410 hand controller and newest firmware (which removes star alignment from the HC btw) and it does indeed still need a usb hub. Luckily, I have one on my setup anyway but thanks for pointing this out as it saved me a lot of time troubleshooting!

[@KopLamp]

You're welcome! Wow, the encoder version. I've heard very good stories about those, not even requiring guiding and such. I have the non encoder one. Must say, I don't have the HC connected at all as I am running things over USB and the ASIAIR primarily.

[@AttemptingAstro]

@@KopLamp that's my hope with the guiding as I live in Bortle 9+ skies and sometimes finding a guide star with an OAG is impossible haha. Still waiting for the "new equipment clouds" to clear to test though. Anyway thanks again and clear skies!

[@jenslankamp6433]

Very informative Martin. Thanks for sharing!

[@KopLamp]

Graag gedaan!

[@KJRitch]

I guess you replaced your CEM40 with the AM5. I read the PE of the AM5 up 20”. I have a C8 and was looking into a CEM40/GEM45. Is your guiding on the AM5 as good as the CEM40 whose PE is supposed to be under 7”?

[@KopLamp]

It definitely is just as good as the CEM40. With guiding. Unguided is impossible due to the PE.

[@exif6839]

That seems to be a little bit chaotic in the difference of this CEM40 sub variants. Therefore does it make sense to upgrade from a Vixen GPD2 with ESCAP motors and LFEP control system? Maybe not…

[@KopLamp]

I don’t have any experience with Vixen mounts, so your guess is as good as mine. What I do know is that both my CEM40 variants are very good mounts. Mount land has been very dull for many manufacturers. But there is a new thing on the horizon. Seems to me that harmonic drives is the new hype. I think you can expect a review of one, on my channel this summer.

[@exif6839]

@@KopLamp Hello Martin, thanks for your answer. And yes, I have seen that there are new „HEM“ mounts on the horizon, also from iOptron. From the price point very interesting and additional with encoder in RA axis. Lightweight and stiff. Maybe the best for my purposes: The photographis and visual use for a TeleVue NP101 refractor telescope or for my other device, a Celestron EHD 800. Both systems with camera and small guide scope, all together below 10kg.

[@cliffhalliwell9955]

I think they also changed the power input socket from 5.5 2.1 in earlier versions to 5.5 2.5. Correct?

[@KopLamp]

I first noticed it in my second CEM40. The 2019 model still had the 2.1mm center pin. Looked up the manual of a CEM26 and there it still says 2.1mm

[@astro-optics]

I have a CEM 26 and a CEM 70 . Mini PC a did my self. 😊

[@KopLamp]

Mini PC should work perfectly. Just as my ASIAIRs.

[@siriusalpha6353]

My CEM40 arrived in Dec 2021 so it is a new one. One week ago I was able to setup the ASIAIR plus on the CEM40. Easy as 1, 2 and 3.... Nope, really not that!!! I just finally arrive on a mid solution to make the PLUS work well on the CEM40. Today I just viewed your video and you said to use a none powered hub between the PLUS and the mount. It is half-working. I need to start the asiair plus WITHOUT the usb of the mount. Then when the wifi has started well then I can plug the USB of the mount and all works well. So why cant I have the mount USB plugged to the PLUS? Well because the WIFI (and even a internet cable) is not starting up. Wow it was not fun. I even send an email to ZWO but no response at all, not even an "accuse-de-reception" from their part. Anyway Martin, thx for the "no-powered hub" trick.

[@KopLamp]

I haven't had much time since making that video unfortunately. I will need to test out a lot of things to be totally certain, but my ASIAIR Pro seems to be unable to control the mount without using the camera as a hub. The ASIAIR Plus however (I own both) seems to be able to control it directly. I also had a faulty USB cable provided with my new CEM40 mount, so you might also want to try changing your cable, if problems persist.

[@siriusalpha6353]

@@KopLamp Hi Martin. Thx for the feedback. I have passed the cable mount by the CMOS camera and yes it works but not completely. Naturally I need to connect directly my guide scope to ASIAIR PLUS but it doesnt work when you start the ASIAIR. Now I cant start the WIFI of the ASIAIR when the guide scope AND/OR the mount cable (which pass by the CMOS camera). So I am using an unpowered hub connected to the Mount cable (which pass by the CMOS camera) and the guide scope which I remove from ASIAIR before I start it so that I can wait to the WIFI (or Lan cable) to work. After the WIFI is on then I plug the unpowered hub cable into the ASIAIR and all is working fine. So my conclusion is that it is not a CEM40 bug that stop the WIFI to work but an ASIAIR PLUS Oper Sys bug. for the moment I will keep this setup/procedure because it is working. Well it is better than nothing :) See ya!

[@Miguel_Noppe]

I'm a Skywatcher owner, no rapid iteration here 😅

[@KopLamp]

That is a good thing and a bad thing at the same time 😅

[@Astronurd]

@@KopLamp If it’s ain’t broken, don’t fix it!

[@KopLamp]

Very true indeed.

[@pstanyer1]

Great review but for a partially deaf person the background music needs removing.

[@KopLamp]

Hi there! Sorry, for that. To make up for it, there will also be a written version of this on Cloudy Nights one way or the other. I'll also try to see how this subtitles thing works on KZbin. Would that help?

[@stevenpanish1115]

@@KopLamp Interesting review but I agree that the music is negative. Distracting.

[@Astronurd]

Too much chopping and changing for my liking. I will stick to a EQ6R pro

[@hael8680]

Anyone uses a USB 3.0 camera in the Ioptron world? Why is this company ignoring USB 3.0 still in 2022?

[@KopLamp]

I am an ASIAIR user, so I don't really care about the USB type of the mount... But USB3 is on the more expensive iOptrons.

[@geomatrix5452]

Because they're CHEAP CHARLIES!