iOptron CEM40 Center Balanced Equatorial GoTo Mount
iOptron CEM40 Center Balanced Equatorial GoTo MountiOptron CEM40 Center Balanced Equatorial GoTo MountiOptron CEM40 Center Balanced Equatorial GoTo Mount
iOptron CEM40 Center Balanced Equatorial GoTo MountiOptron CEM40 Center Balanced Equatorial GoTo MountiOptron CEM40 Center Balanced Equatorial GoTo Mount

iOptron CEM40 Center Balanced Equatorial GoTo Mount

  (5 Reviews)
✓ 2 year warranty


1x in stock shipped 1-2 working days

About this product

Model:  iop_cem40_head_ip_hc
Part Number:  C402A

Next-generation design! 

The iOptron CEM40 is a remarkably capable centre-balanced equatorial mount and the first to feature iOptron's next-generation design.

Weighing in at only 7.2 kg (15.8 lbs), it can support a payload of up to 18 kg (40 lbs), which is remarkable! 

Features include iOptron's integrated 'iPolar' electronic polar finder scope, which ensures accurate polar alignment even when the pole star is obscured. 

Large Clutch levers on the quick-lock drive engagement system make it easy to lock the gears into place. 

Innovative iOptron Technology

The patent-pending Universal Self-Centering Saddle 'USCS' accommodates Losmandy and Vixen-style dovetail plates. It also accepts Sky-Watcher & Celestron dovetails.

In addition, the CEM40 features an ultra-quiet, stepper motor drive system for precise pointing and tracking. 

Computerised Mount Features

Using iOptron's Go2Nova® 8410 GOTO hand controller, you can automatically point to and centre any celestial target (depending on date and location) in its 359,000+ object database! 

With the included tripod, 5 kg counterweight (8027) and computerised GOTO technology, observers are just a telescope away from an impressive viewing experience!




  • New design, centre-balanced equatorial mount (CEM) for maximum payload and minimum mount weight
  • Designed for both visual astronomy and astrophotography
  • Maximum payload of 40 lbs (18 kg) with a mount weight of only 15.8 lbs (7.2 kg)
  • All metal and CNC machined with red/black anodising
  • Easy-to-use quick-lock gear clutches
  • Integrated iPolar electronic polar finder
  • Low periodic error (< ± 7 arc seconds)
  • Permanent periodic error correction (PPEC)
  • Precision stepper motor for precise GOTO and accurate tracking
  • Go2Nova® 8410+ controller with Advanced GOTONOVA® GOTO Technology with a built-in heater
  • Integrated ST-4 auto-guiding port
  • 32-channel Global Positioning System (GPS)
  • USB communication port
  • Cable management system
  • New 8” Losmandy/Vixen saddle
  • Optional 1.5 or 1.75" inch heavy-duty stainless steel tripod (5kg / 8kg) 
  • Optional WiFi for mount control via SmartPhone/Tablet/Computer

Go2Nova Hand Controller 8410

  • 200,000+ object database
  • 8-line, 21-character backlit large screen LCD
  • Low-temperature operation as low as -20ºC
  • User-friendly interface
  • Nine-speed slew control with quiet mode
  • Large object database

What's in the box

Supplied in two boxes. 

  • CEM40 mount head
  • CW shaft
  • GO2Nova 8410+ hand controller with cord. 
  • 1x 11lb (5kg) Counterweight (if ordered with a tripod)
  • 1.5" or 1.75" steel tripod (if selected)


Mount Center-balanced Equatorial Mount (CEM)
Max Payload 40 lb (18 kg), excluding counterweight*
Mount weight 15.8 lb (7.2 kg)
Payload/Mount weight ratio 2.5
Structure Material     All metal, CNC machined, red/black anodised
Latitude adjustment range 0º ~ 60º(special CW shaft mounting if <10° )
Azimuth adjustment range ± 6º
Tracking accuracy (PE)** <±7 arcsec
Period 400 sec
Worm diameter     Φ 17mm, Brass
Right Ascension worm wheel     Φ 110mm, 216 teeth, zero backlash
Declination worm wheel Φ 110mm, 216 teeth, zero backlash
Right Ascension axis shaft Φ 45mm steel
Declination axis shaft     Φ 45mm steel
Right Ascension bearings Φ 68mm
Declination bearings Φ 68mm
Counterweight shaft     Φ 28x410 mm, Stainless Steel (1.2 kg)
Counterweight 1x 5kg (11lbs) 
Motor Precision stepper motor, 1.8º/128x micro-step
Motor resolution 0.08 arcsec (200 PPS)
Transmission Synchronous belt
Hand Controller     Go2Nova® 8410+, 8 line 21 character LCD
Star Database 359,000+, star identification
Power DC 12V, 5A
AC adapter 100V ~ 240V (included)
Power consumption 0.6A (Tracking), 0.9A (GOTO)
Power-down memory Yes
Polar scope Internal iPolar electronic polar scope
Meridian treatment Stop (0-10° pass), flip
Operation temperature -20°C ~ +45°C
Zero position Automatic zero search
Dovetail saddle 8" Losmandy D & Vixen
Max slew speed 4.5°/sec (1080x)
Guiding port ST-4
Communication port USB
WiFi External (optional)
Cable Management DC12V (3A), ST4,USB
Tripod Optional 1.5" or 1.75" Stainless Steel tripod or tri-pier
Hard Case Optional
Operation Temperature -10ºC ~ 40ºC
Warranty Two-year limited

* This is only a guideline. Some telescopes are unusually long or large for their weight, so they may require a larger mount. Also, max payloads for astrophotography are typically 1/3 less than for visual astronomy.
** Measured with encoder, 400 seconds

Downloads / Manuals


iOptron CEM40 Instruction Manual


Coming soon

iOptron Telescope ASCOM Driver:

Coming soon

Customer reviews

Average Rating (5 Reviews):  
Write a Review and share your opinions!

Rating (max 5):  
Fantastic Mount
04 April 2024  | 

Full disclosure - due to the interminable cloud cover over the winter and spring I have not had a chance to use this mount for more than a couple of very short test sessions.

I decided to move from my Skywatcher HEQ5 (Rowan) because I wasn't happy with the guiding accuracy I was getting. Originally I was thinking along the lines of the Skywatcher EQ6-R Pro which would give me significantly greater load capacity; however, I was fortunate enough to find the iOptron CEM40 in a deal from FLO. I was concerned that the iOptron mount might not give me enough additional capacity but had some really helpful guidance from FLO (thanks Chris) and realised that the CEM40 would be an ideal mount for my 11kg imaging rig (I'm also not expecting to increase the weight of my kit so no need to future-proof).

On the couple of occasions I tested the mount it performed extremely well. The iPolar function seems to work well after calibration (PA error of 0 according to PHD2); and I was getting good guiding for the few minutes after set up and before the cloud rolled in.

I'm looking forward to being able to have a proper AP session!

Rating (max 5):  
Great mount for the money
18 November 2023  | 

As usual FLO service & shipment are peerless. The mount is probably at the max size I would consider portable or ďthrow and goĒ. If youíre small it might be a little heavy. Anyway, works great with both 4Ē & 5Ē APO refractors, very stable and ultra precise goto once itís polar aligned. Even handles my StellaLyra 10Ē Newt. Not used for imaging just yet, but will be giving it a go for this on the next decent long cold clear night.

Rating (max 5):  
Overall and excellent mount
09 August 2021  | 

The mechanics and build are excellent - it is a beautiful piece of machinery. Updating the firmware is a real pain in the a*se, even when you know itís a possible issue in advance, and updating the hand controller firmware requires you to buy a RJ9 to RS232 lead plus a RS232 to USB converter if you bought your PC anytime after the 1900s. Neither are included and there is no *modern* alternative. Theyíre not expensive - itís just annoying that after spending the best part of £2k on a mount, there is no way to update the firmware with the leads provided. The included instructions were for the wrong mount too, but theyíre all online of course. IOptron email support are distinctly failing to help on this either - though of course FLO have helped as much as they could.
Once you surmount these teething issues, itís a great mount and I would recommend it - especially if you need portability with 18kg visual or ~10kg imaging payload capacity.

Rating (max 5):  
Changes to CEM40 mount
01 May 2021  | 

We have had a recent disappointing experience with a CEM40 we ordered. In the end we sent the mount back and asked for a refund which we received no problem from FLO. We just want to make anyone contemplating buying this mount aware of a few things. It is likely that the mounts port configurations might change so please consult the iOptron website to be fully aware of any changes, also ask the guys at FLO to be sure that any current changes to the mountís connectivity suits your requirements. We didnít test out the mount so we assume its functionality with the handset is OK but we did have problems with a loose USB connection which is now the only one to the mount that handles all of the usb inputs and is the connection to the iPolar. Anyone also buying the case at the same time should note that iOptron will transport the mount in the case and so the it will not necessarily arrive in pristine order. We have given the mount one star to get people to look at this review it isnít a reflection on how good it performs as we didnít get to test that.

Rating (max 5):  
CEM 40
30 July 2019  | 

Received this mount last week, FLO were excellent service. I been out a few times under limited clear skies. The Ipolar works a treat, my first attempt getting 3.5 arc minutes within the NCP.
The tracking seems very good as is the goto's . Also only had a limited time guiding using ST4, but PHD2 was giving excellent results.
The 2 inch tripod is very nice and extremely stable.
all in all im a very happy man


Please fill in the form below to ask a question.

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Q1. Does the CEM40 mount fit the iOptron tri-pier?

Yes - the CEM40 fits directly to the tri-pier, no additional adapters are required.

Q2. Does the CEM40 mount head only package include tripod alignment pegs

We have checked and the mount head only does include AZ alignment pegs to use with iOptron's tripod or Tri Pier.