iOptron CEM120 Mount

CEM Design: A 2:1 Payload Ratio for 52 kg Instruments

The core of the CEM120's capability is its Center-Balanced Equatorial Mount architecture. By positioning the payload's center of gravity directly over the pier's central axis, the design achieves a level of natural stability that allows for a significantly higher payload capacity relative to its own weight. This makes the 26 kg (57 lbs) all-metal mount head capable of securely handling large optical tubes and imaging trains up to 52 kg (115 lbs),.

The mount includes two 10 kg counterweights and a 4.5 kg stainless steel counterweight shaft to balance your payload. The Losmandy D dovetail saddle is spring loaded and individually adjustable, with three sets of mounting holes to move it back and forth.

Precision Drive System: <0.15 arcsec RMS Tracking with Encoders

Massive Φ216mm, 360-tooth zero-backlash worm wheels are paired with Φ26mm worms on both axes, resting on huge Φ125mm bearings. This robust mechanical system is driven by a precision stepper motor with 128 micro-steps, resulting in a fine pointing and tracking resolution of just 0.07 arc seconds.

The standard CEM120 model features Permanent Periodic Error Correction (PPEC) to algorithmically reduce the worm gear's inherent tracking errors over its 240-second period. For the most demanding applications, the high-resolution encoder-equipped versions (CEM120EC and CEM120EC2) use Real-time Periodic Error Correction (RPEC). These encoders correct tracking in real time for a periodic error of less than 0.15 arc seconds RMS. The encoder resolution is 0.035 arc seconds.

Go2Nova 8410 Control: GPS, WiFi, and Remote Observatory Operation

The CEM120 includes the Go2Nova® 8410 controller with an 8 line, 21 character LCD. A built-in 32-channel GPS automatically inputs the date, time, and location for a fast and accurate setup, while the automatic zero search function finds the mount's home position, ensuring repeatable and reliable startup every time. The hand controller's database contains over 212,000 objects, and its integrated heater keeps the LCD working at temperatures as low as -20°C (-4°F).

While the hand controller provides full standalone access, the CEM120 is designed for modern computer control. With built-in WiFi, a dedicated LAN port, and USB and RS232 connections, you can connect directly to the mount for full remote operation. iOptron supplies an ASCOM driver for control from a computer.

Advanced Cable Management: 10+ Integrated Power and Data Ports

The CEM120 has a pre-wired Cable Management System (CMS) so you can connect accessories and imaging equipment without cables tangling or snagging while the mount slews or tracks. The output ports sit at the back and sides of the dovetail saddle and are fed from the CMS input panel.

• Power Outputs: Two 12V 1A sockets (2.1 x 5.5 mm, centre positive) and two DC sockets (one 2.5 x 5.5 mm, one 2.1 x 5.5 mm) with a maximum specified current of 5A; their voltage follows the input voltage.
• Data Ports: Three USB 3.0 ports and two USB 2.0 ports at the saddle.
• Control Ports: An ST-4 guiding port, an AUX (DIN-422) port, an iPORT for iOptron accessories such as an electric focuser, a 6P6C port and a dedicated USB port for the optional iPolar electronic polar scope.

Observatory-Grade Adjustments: 0° to 68° Latitude Range

The latitude can be set anywhere from 0° to 68° (0.5 arcmin division), so the mount can be used from the equator up to 68° latitude. The azimuth adjustment gives ± 5° (3 arcmin division) for fine-tuning your polar alignment.

The CEM120 does not come with an optical polar scope. You can polar align with the hand controller's Polar Iterate Align routine, with alignment software such as TPoint with TheSky, PemPro or Alignmaster, or with the optional internal iPolar electronic polar scope (#3339A-120), which plugs into the mount's built-in iPolar USB port. A pier is optional and not included; the mount base measures 210 x 230 mm for interfacing with a custom pier plate.

CEM120, CEM120EC & CEM120EC2: Choosing Your Encoder Configuration

The CEM120 is available in three distinct versions, which differ in their high-resolution encoders for real-time tracking correction. The core mount mechanics, 52 kg payload, and connectivity are identical across all models, allowing you to choose the level of tracking precision your work requires.

• CEM120: The standard model uses its precision worm gear system and Permanent Periodic Error Correction (PPEC). Its periodic error is rated at less than ±3.5 arc seconds.
• CEM120EC: This version adds a high-resolution encoder on the Right Ascension (RA) axis. With real-time PEC (RPEC) it reduces periodic error to less than 0.15 arc seconds RMS, and the EC versions support push-to operation.
• CEM120EC2: This model has dual high-precision encoders on both the Right Ascension (RA) and Declination (DEC) axes, with the same < 0.15 arcsec RMS periodic error and RPEC as the CEM120EC, and push-to operation.