iOptron CEM40 Mount Overview

The iOptron CEM40 is one iOptron's most popular mounts they sell. It is widely popular due to its precision tracking, stable platform and huge following behind it. The CEM40 features a 40-pound capacity for astrophotography and a wide variety of optical tubes.

[@Wolfie6020]

Thanks for a very detailed and informative review. This looks like a fabulous mount

[@otrondal]

Thank you for a nice video. I love this type of new technology mounts. I have a 10 inch SC on an old Opticraft Maching mount. Way to slow slewing speed. Time for me to upgrade (And I bite nails too).

[@KJRitch]

Looks like current CEM40 ship with the 8410 hand controller which has no serial or USB port. ASIAIR and NINA would connect directly to the mount USB port.

[@SKYST0RY]

I am planning to purchase a mount next week, and have it narrowoed down to the Sky-Watcher EQ6-R with wifi, the new ZWO AM5 harmonic drive or the iOptron CEM40. I was really glad to come across your review. I plan on focusing on deep sky objects and will be using mainly reflectors such as my SCT with between a 1400 mm and 2100 mm focal length. Do you feel the CEM 40 would be adequate? I've also heard a few stories about the CEMs have delicate gears that can easily be cammed and damaged. I'd love to know your thoughts.

[@MaximumAstronomy]

Hello! I have not tried one of the new harmonic style mounts but I do know they seem to have a little bit more periodic error than traditional mounts with counterweights. It’s not major or big differences but it’s something. The CEM gear problem was mostly early days on the CEM60 where they had lots of problems but these newer CEM40/70s are tanks. I take mine everywhere and I love how easy it is to take anywhere. Solid. Stable. Really good guiding performance. I use my C8 on it often and runs like a workhorse. The bearings are so easy to balance just right too which is a dream. The Sky-Watcher is a tried and true mount as well with great results. But the CEM40 is more portable as it’s half the weight of the EQ6R but similar in terms of payload and performance in a smaller profile. I’d go for a CEM40 if I was purchasing all over again, but ultimately it’s your choice! Clear skies!

[@SKYST0RY]

@@MaximumAstronomy Thank you for the info. I am leaning toward the CEM 40, or perhaps the slightly newer GEM 45. The GEM seems to have somewhat better cable layout and a bit more payload, and people are reporting insanely high accuracy, even unguided.

[@KJRitch]

Do you still have this mount or did you replace it with the AM5? I want to upgrade from my AVX. I have a C8 and with my image train the mount is close to 19lbs. Do you have to connect the ASIAir or a NINA MiniPC to the handset to control the mount?

[@MaximumAstronomy]

I just barely upgraded from this to an AM5, but I will say I have had a few issues with it with performance. I’ll be making a video this week actually on that topic, but I LOVED my CEM40 and honestly wish I wouldn’t have gotten rid of it at this point. To control the mount you just need to plug everything in and then connect to USB. I didn’t try without the hand controller to see if it was possible.

[@KJRitch]

What is the advantage of the CEM40 vs the GEM45. Both the same price. $400 more now since three years ago. Thanks. I guess with a 20lb payload I would need to order and additional 11lb counter weight. Thanks.

[@MaximumAstronomy]

@@KJRitch Basically just the design, if you’d like a traditional EQ with the GEM45 or the center balanced variant (CEM40). Both are going to do basically the same job, so it’s preference thing. And yes you’ll need another weight likely to balance properly.

[@malanstecker]

Nice review! In the latitude/altitude window where should the number lie? At the top, middle or bottom of the window? I do not see an index mark, so is the latitude value only accurate to plus or minus 15-degrees?

[@jcims]

Look again, there's a small arrow on the left extending from the back surface of the hole.

[@MrGuilletv]

Great vídeo and review. U think cam40 canción handle a 9.25 SCT?

[@MaximumAstronomy]

For visual it should be able to handle the 9.25. But for deep space astrophotography it might be a little challenging

[@ManishFrenchStudio]

Superb 🇮🇳💖💖

[@astropetev]

Nice review, thank you. The design seems to give plenty of clearance on the telescope side. So will this mount cross the meridian to extend an imaging run without having to do a 'meridian swap'? And can it GOTO the 'wrong' side, within safe limits of course?

[@MaximumAstronomy]

Plenty of clearance and it will track about 25 degrees past the meridian, but there is no hard stop there and it will collide with the mount so it’s best to set it in the hand controller to go past a certain amount and then it warn you to flip. GoTo will always go on the proper side of the meridian the target falls, and I don’t think there is a way bypass that.

[@astropetev]

Very promising, thank you. Fair enough, no wrong side GOTO. I wonder if it is possible to manually drive the mount to a target on the wrong side while reading RA and DEC coordinates on the handbox screen? I've seen that done on an EQ6 Pro mount. Obviously it doesn't really matter for visual use, but if imaging when the target will be crossing the meridian within an hour or so it's a pity to have to wait and lose data.

[@freeandcriticalthinker4431]

Nice video, hey question for you from a Newb…. Can you polar align , without huge frigging around with it, without the Ipolar as I have this mount, which has never worked from Day one? Meaning that the Ipolar would never connect and this CROOKED company like their usual MO (and plenty of other companies from that country….. (yes it’s their culture. CUTHROAT…) has left me high and dry with no factory support. Long story on that, but I had some huge long drawn out chronic health issues where I had to lay low for a couple years and they used THAT opportunity to deny me a warranty for a brand new mount I bought AND I had reported the problem using the Ipolar not connecting many times early on. Replacing the camera did no good, as I managed to do it myself. It’s put me off so much, that I am on the edge of just giving this whole nightmare up and releasing my hope in humanity that I kept hoping would show their face to uphold that basic value….. but nope, didn’t happen and I am torn on what to try and do, needless to say if I buy another mount you know which brand that I will not at all consider. Any of your own experience with their “CS” that you have had and would be willing to share…. Regardless thanks for your video, good job. Cheers

[@yf222000]

Hi. Great setup. Can I ask what is the total weight of your imaging OTA setup? Thanks.

[@MaximumAstronomy]

It’s about 25 pounds

[@yf222000]

Maximum Astronomy. Thx. My current setup on this same mount is about 19 lbs. my future rigging is going to push the limit of this mount to the very edge at 33-34. 🤦🏻‍♂️

[@penguin272]

@@yf222000 keep in mind that CEM40 has very easy axes so you may add weights to balance DEC carefully. if you are already at 33lbs better go for the bigger brothers

[@area51xi]

Just got my CEM40. I'm at lat 34.5. Should I use the 0-35 or 25-60 range position?

[@area51xi]

Actually, looks like it doesn't really matter...

[@astroterrace]

Nice detailed review.

[@frankskeen1310]

Planning on getting this mount myself and I enjoyed your video. It was done well and video was sharp. I have a Skywatcher HEQ PRO and this looks like it will be a nice upgrade to use my 8 inch Meade SCT ACF scope. Weight will be close. Did your come with 1 or 2 counter weights ? Just wondering.

[@MaximumAstronomy]

It comes with 1