iOptron CEM120EC Goto EQ Mount

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iOptron CEM120EC Goto EQ Mount

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The innovative mount with high precision encoders, for larger telescopes.


Recognizing the growing demand for an accurate and stable equatorial mount with the versatility to carry larger instruments and more complex imaging arrays, iOptron has created the CEM120EC. It offers the benefits of thie “center balance” design: stability, accuracy, and smooth mechanical operation, while being capable of carrying a payload up to 52 kg. The “center balance” design’s natural stability is due to its focusing the mount along with the payload's weight directly over the center of the pier or tripod.

The CEM120EC's performance is demonstrated by its low periodic tracking error of <0.15 arcsec RMS. Along with the stability aspect, the CEM120EC features an advanced cable management system consisting of more ports in more locations preventing tangle ups and reducing the chance of fractured cables. It also adds some new features to the CEM family like Wi-Fi and LAN for remote operation and easy to use, reliable clutches on both axes.


  • A new design, center-balanced equatorial mount (CEM) for maximum payload with natural stability
  • Observatory astrophotography mount ideal for both visual and astro-photographers
  • Payload of 52 kg with the mount weight of 26 kg
  • Easy to use and reliable gear clutches
  • Adjustable counterweight shaft for 0º latitude operation
  • Precision altitude and azimuth adjustment.
  • Precision stepper motor with 0.07 arcsec accuracy for precise GOTO and accurate tracking
  • Polar alignment routine for those who can't see the SCP
  • Go2Nova® 8407 V2 controller with Advanced GOTONOVA® GOTO Technology with built in heater
  • High precision tracking with low periodic error (PE)<0.15 arcsec RMS
  • Real time periodic error correction (RPEC)
  • Built-in 32-channel Global Positioning System (GPS)
  • Built-in WiFi and LAN for remote operation
  • Integrated ST-4 autoguiding port
  • Advanced cable management system with more choices
  • Spring loaded, individual adjustable Losmandy saddle


  • CEM120EC mount head x1
  • Go2Nova 8407 V2 hand controller x1
  • 10 kg counterweight x2
  • Counterweight shaft x1
  • Hand controller cable x1
  • Serial cable (#8412) x1
  • Mount Center-balanced Equatorial Mount (CEM)
    Payload 52kg, excluding counterweight*
    Mount Weight 26kg  
    Payload/Mount weight 2:1 
    Material All Metal 
    Latitude adjustment range 0°~ 68° (0.5 arcmin division)  
    Azimuth adjustment range ± 5° (3 arcmin division)
    Tracking accuracy (PE) < 0.15 arcsec RMS
    Worm Period 240 sec
    PEC Real time PEC (RPEC)
    RA & Dec worm wheel Φ216mm, 360 teeth, zero backlash
    Worm Φ26mm
    RA & Dec Axle Φ80mm, steel
    RA & Dec Bearings Φ125mm
    Counterweight shaft
    Φ38.1x 540 mm (SS, anti-slip, 4.5kg)
    Mount base size
    210 x 230mm
    Motor drive
    Precision stepper motor w/128 micro-step
    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
    Polar Scope
    Not Included
    Meridian treatment
    Stop (0-14° pass), auto flip
    Zero Position Automatic zero search
    Park Position Horizontal, vertical, current, alt/azi input
    Level Indicator Yes
    Dovetail saddle
    Losmandy D, 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
    Optional pier
    Two year limited

    * These are only guidelines. Some telescopes are very long or very big for their weight and may require a larger mount. Remember also that imaging requirements are more rigid than visual observation.

    Item Details
    Optional Items
    Counterweight 10kg (Add $189.00)
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