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iOptron CEM120 Center Balanced EQ Mount

SKU : IO-7300

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  • 115 lbs payload capacity
  • Tracking accuracy of less than 0.15 arcsec RMS
  • 12 port cable management saddle
  • LAN, RS232, USB and Wifi Control options for remote observatory setups
  • Built-in 32 Channel GPS 
  • Note: If you are going to mount this atop an already purchased Tri-Pier (8034) you will need an adapter plate #IO-8036-120. (You can find this below in the Recommended Products card.) Otherwise we advise to get the IO-8037 Tri-pier which already had the adapter plate attached.

    Product Details

    • Mount Specs:
      • Mount: Center-balanced Equatorial Mount (CEM)
      • Payload: 52kg (115 lbs), excludes counterweight
      • Mount Weight: 26kg (57 lbs)
      • Payload/Mount weight ratio: 2/1
      • Material: All metal
      • Latitude Adjustment Range: 0- 68 deg (0.5 arcmin division)
      • Azimuth Adjustment Range: (+/-) 5 deg (3 arcmin division)
      • Tracking accuracy (PE): < (+/-)3.5 arcsec
      • Worm Period: 240 sec
      • PEC: Permanent PEC
      • Right Ascension Worm Wheel: 216mm, 360 teeth, zero backlash
      • Declination Worm Wheel: 216mm, 360 teeth, zero backlash
      • Worm: 26mm
      • Right Ascension Axle:80mm, steel
      • Declination Axle: 80mm, steel
      • Right Ascension Bearings: 125mm
      • Declination Bearings: 125mm
      • Counterweight shaft: 38.1x 540 mm (SS, anti-slip, 4.5kg)
      • Counterweight: 10 kg (22 lbs)
      • Mount Base Size: 210 x 230 mm
      • Motor Drive: Precision stepper motor w/128 micro-step
      • Resolution: 0.07 arc seconds
      • Slew speed: 4°/sec (960x) max.
      • Hand Controller: Go2Nova 8407 V2, 8 line 21 character LCD
      • Power Requirement: DC 12V, 5A
      • Power Consumption: 0.7A (Tracking), 1.8A (GOTO)
      • Polar Scope: Optional electronic polar scope
      • Meridian Treatment: Stop (0-14 deg pass), auto flip
      • Zero Position: Automatic zero search
      • Park Position: Horizontal, vertical, current, alt/azi input
      • Level Indicator: Yes
      • Dovetail Saddle: Losmandy D, 17.2" (437mm)
      • GPS: Yes
      • Guiding Port:ST-4
      • Communication Port: RS232, USB, LAN, WiFi
      • Cable Management: 2xDC12V (1A), DC5V(1A), 2xDC (5A), ST4, 6P6C, 4xUSB2.0, USB3.0 (powered), USB for PS, AUX
      • Pier/Tripod: Optional pier
      • Warranty: Two year limited


      With the growing demand for accuracy, heavy capacity, stability, and versatility in an equatorial mount, iOptron created the CEM120 to meet all these needs. The CEM 120 like all center balance designs are naturally stable is due to putting the weight of the telescopes directly over the center of the pier or tripod.

      The mount’s performance is demonstrated by its low periodic tracking error that is +/- 3.5 arc seconds RMS. The CEM120 features an advanced cable management system consisting that prevents tangle ups and reduces the chance of fractured cables. It also adds some new features to the CEM family like Wi-Fi and LAN for remote operation.

      • specifications

        Azimuth Range Plus or minus 5 degrees
        Dec Worm Wheel216mm/360 teeth
        Free ShippingYes
        Head DesignEquatorial
        Instrument Capacity115 lb
        Latitude Range 65 degrees
        Mount Head Weight52.6lb
        RA Worm Wheel216mm/360 teeth
        Saddle WidthD Series
        Telescope ConnectionLosmandy Style
        Tracking ModesEQ North & EQ South
        Tracking RatesLunar & Sidereal & Solar
        Warranty2 Year Warranty
        weight57 lb
        Worm Period240 seconds
      • included items

        • CEM120 mount head x1
        • Go2Nova 8407 V2 hand controller x1
        • 10 kg counterweight x2
        • Counterweight shaft x1
        • Hand controller cable x1
        • Serial cable (#8412) x1

      Product Reviews

      Customer Reviews
      4.6 Based on 9 Reviews
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      Michael P.
      United States

      I worked with some fine people who helped me get all I needed from this fine equipment!

      The OPT team is always my go to and I will be back for my next purchase!

      United States United States

      I now own two. A beautifully engineered machine.

      Mike B.
      Canada Canada

      Solid Mount

      CEM120 are a great value. Very sturdy construction, no plastics. Absolutely love the built in thru cabling, the best on the market. Guiding is excellent even with my 12" sct. The no backlash design really works well.

      Wade D.
      United States United States

      Now THIS is a Mount!!!

      I've been using a CGEMII for over a year. I decided it was time to upgrade. Boy did I ever! Last night, I got 14min subs in Ha and they not only stacked flawlessly, but I was able to produce the most incredible Narrowband image of the Crescent Nebula I've yet achieved. Captured with my new Celestron 9.25 Edge HD no less (not exactly a light weight OTA). Guiding results were incredible, best I've ever scene especially compared to my last mount. Its very high quality, with solid construction and incredible features. I love that everything routes through the saddle, from my USB to my camera, to the cooling of said camera, everything. Word to the wise, wire up some of your own custom harnesses to take advantage of this incredible feature (zip-tied USB cable, custom harnesses for the power to both the mount itself and the aux power for the accessories on the scope itself). Delivery was fast and efficient and arrived in pristine condition. Finally, as an added note, the service was exemplary. I had a chat with a salesman concerning the quality of this mount. I had read some horror stories. He gave me an honest opinion, sighting quality issues had been addressed, and an alternative I had been holding out for for this mount may have quality issues of its own. I may have just gotten lucky, but I still feel like I was dealt with honestly and openly. If your looking for an imaging mount and am ready to trade up to a truly "big boy" mount, look no further. I couldn't be happier.

      Dave B.
      United States United States

      Nice Mount

      I've only had it out twice due to the poor weather, but it performs nicely. Tracking is very good. I was able to go unguided for 240 seconds with my 10" RC @2,000mm focal length without PEC training. Not all images are keepers, but @ 120 seconds I was able to use all images. Looking forward to some clear nights to fine tune everything. I'm running it as an ASCOM mount with The Sky X Pro. I really like the way the gears engage. I upgraded from the CEM60 and don't miss the magnetic locks.

      A OPT Telescopes Customer
      Mark R.
      United States

      Well designed mount!

      I've had enough time to properly explore enough of this mount to say it performs as expected. It's well built with an awesome payload rating. I guide no matter what, but for being the non-ec version, it performed well during a few unguided tests. I do recommend this for anyone looking for a higher payload capacity mount but doesn't want to spend double, if not triple, on other mounts in it's weight range. And of course, as always, OPT has substantial customer service. They always have an answer or solution to my inquiries/questions that I have for them, plus the shipping is fast and cheap.