iOptron CEM120EC mount with encoder on RA axis

iOptron CEM120EC mount with encoder on RA axis

DESCRIPTION
The iOptron CEM120EC is a center-balanced equatorial mount (CEM) built for demanding astrophotography and observatory use. Its innovative central balance design places the combined weight of the mount and payload directly over the tripod or pier, providing exceptional mechanical stability — even with large telescopes or complex imaging setups up to 52 kg.

Equipped with a high-resolution encoder on the Right Ascension (RA) axis, the CEM120EC delivers ultra-precise tracking with a periodic error of less than 0.15 arcseconds RMS. This is corrected in real time using RPEC technology. The high-precision stepper motors with 128 microsteps and 0.07 arcsecond motor resolution enable smooth and accurate GOTO movements, up to 4°/sec.

The mount features precision polar alignment adjustments (latitude 0°–68°, azimuth ±5°), easy-to-use spring-loaded axis clutches, and an advanced cable management system with a wide variety of integrated ports, including USB 2.0/3.0, 12V power, ST-4 guiding, RS232, LAN, and Wi-Fi.

Designed for automated remote observatories, it includes a 32-channel GPS, built-in Wi-Fi and LAN, Go2Nova® 8410 controller with heater, and full meridian treatment control (stop or auto flip). The mount supports automatic zero-position search and multiple park positions (horizontal, vertical, current, or user-defined alt/az).

The adjustable Losmandy D-style saddle is spring-loaded for secure and precise mounting. Optional support includes the Tri-Pier 360 and permanent piers. The package includes the mount head, hand controller, 2 × 10 kg counterweights, and a 540 mm stainless steel counterweight shaft.

TECHNICAL SHEET

• Mount type: Center-balanced Equatorial Mount (CEM)

• Payload capacity: 52 kg (excluding counterweights)

• Mount weight: 26 kg

• Payload-to-mount weight ratio: 2:1

• Material: All-metal construction

• Latitude adjustment: 0° to 68° (0.5 arcmin increments)

• Azimuth adjustment: ±5° (3 arcmin increments)

• Periodic error (RA, with encoder): < 0.15 arcsec RMS

• PEC: Real-time periodic error correction (RPEC)

• Worm period: 240 seconds

• RA/DEC worm wheels: Ø216 mm, 360 teeth, zero backlash

• RA/DEC axles: Ø80 mm, steel

• RA/DEC bearings: Ø125 mm

• Worm diameter: Ø26 mm

• Counterweight shaft: Ø38.1 mm × 540 mm, stainless steel, anti-slip, 4.5 kg

• Counterweights included: 2 × 10 kg

• Mount base dimensions: 210 × 230 mm

• Motor type: Precision stepper with 128 microsteps

• Encoder resolution (RA): 0.035 arcsec

• Motor resolution: 0.07 arcsec

• Slew speed: up to 4°/sec (960×)

• Hand controller: Go2Nova® 8410, 8-line LCD (21 characters/line)

• Power input: 12 V DC, 5 A

• Power consumption: 0.7 A (tracking), 1.8 A (GOTO)

• Polar alignment: Optional iPolar electronic polar scope

• Meridian treatment: Stop (0°–14°), auto flip

• Zero position: Automatic search

• Park positions: horizontal, vertical, current, alt/az input

• Level indicator: Yes

• Dovetail saddle: Losmandy D-style, spring-loaded, individually adjustable

• GPS: Integrated, 32-channel

• Guiding port: ST-4

• Communication ports: RS232, USB, LAN, Wi-Fi

• Cable management:

  • 2 × DC 12V (1 A)

  • 2 × DC (5 A)

  • ST-4

  • 6P6C

  • 2 × USB 2.0

  • 3 × USB 3.0

  • USB for iPolar

  • AUX

• Operating temperature: -10°C to +40°C

• Tripod/pier: Optional pier or Tri-Pier 360

• Warranty: 2-year limited

PACKAGE CONTENTS

• CEM120EC mount head (#7320-EC)

• Go2Nova® 8410 hand controller

• Hand controller cable

• Stainless steel counterweight shaft

• 2 × 10 kg counterweights (#7325)