iOptron CEM70 Mount

A 70 lb Payload on a 30 lb Center-Balanced Frame

The CEM70's center-balanced design places the payload's center of gravity directly over the tripod or pier, which gives maximum payload with natural stability. The all-metal mount supports a 31.8 kg (70 lbs) payload on a head that weighs 13.6 kg (30 lbs).

The mount's rigidity is anchored by Φ55mm steel axles running in oversized Φ80mm bearings on both axes. The spring-loaded 8" Losmandy D & Vixen dual saddle accepts both dovetail standards.

The CEM70 Drive Train: 151mm Worm Wheels and 55mm Axles

Every CEM70 is built around a robust drive train designed for precision and stiffness. Both the Right Ascension and Declination axes use large Φ151mm, 248-tooth worm wheels paired with Φ21.2mm worms. The worm period is 348 seconds.

The worms are driven by precision stepper motors with 128 micro-steps, yielding a GoTo resolution of 0.07 arcseconds. This fine control allows for precise pointing, accurate tracking, and maximum slew speeds of up to 3.75° per second (900x) to quickly move between targets.

From < ±5 Arcsec PPEC to < 0.3 Arcsec RMS with Encoders

The CEM70 family offers distinct levels of tracking accuracy to match your imaging needs. While the core mechanics are identical, the method of error correction defines each version's performance.

• CEM70 (Standard): Utilizes Permanent Periodic Error Correction (PPEC) to keep native periodic error below ±5 arcseconds.
• CEM70EC (RA Encoder): A high-resolution encoder on the Right Ascension axis enables Real-time PEC (RPEC), which measures and corrects worm gear errors as they happen. This reduces periodic error to less than 0.3 arcseconds RMS.
• CEM70EC2 (Dual Encoders): Adds a second high-resolution encoder to the Declination axis, so both axes are monitored and corrected in real time. This is dual-axis real-time PEC; the periodic error figure is the same < 0.3 arcsecond RMS.

Integrated iPolar and 32-Channel GPS for Fast Setup

Every CEM70 has the iPolar electronic polar scope built in. You install the iPolar software, connect a USB cable between the mount's iPolar port and a computer, and follow the on-screen instructions. It is simple and fast, even when the pole star or part of the sky is blocked. The hand controller also offers BrightStar Polar Alignment (Polar Iterate Align) for a coarse alignment when the pole cannot be seen.

The internal 32-channel GPS provides your location, date and time to the GoTo system. The latitude adjustment range is 0° to 65°, and the azimuth range ± 4°.

Go2Nova 8410 Controller with Automated Meridian Flips

The included Go2Nova 8410 hand controller is your command center for alignment, GoTo slewing, and tracking. Its large 8-line, 21-character LCD is easy to read, and the controller's database contains over 212,000 objects. An integrated heater keeps the LCD working at temperatures as low as -20°C (-4°F).

The mount handles meridian treatment: it can stop or pass the meridian by 0-10° and then flip automatically to continue tracking a target across the sky. Other key functions include an automatic zero search to find its home position and an ST-4 autoguiding port for control from your imaging software.

Advanced Cable Management with Options for USB 3.0, WiFi, and NUCs

The CEM70 routes power and data through the mount body to ports on or near the saddle. The port configuration varies by version to suit different imaging setups.

• Standard Versions (CEM70, CEM70EC, CEM70EC2): The saddle hub provides 2x DC12V (3A) outputs and 3x USB 2.0 ports, plus 1x DC in/1x DC out and an iPort.
• W Versions (WiFi & USB 3.0): Add built-in WiFi and a hub with 3x USB 3.0 ports, 1x DC12V (3A), 1x DC in/2x DC out and an iPort.
• iGuider Version: Includes built-in WiFi, 3x USB 3.0 ports, and a more extensive power hub with 2x DC12V (3A) outputs and 2x DC outputs.
• NUC Versions: Feature dedicated DC 19V power, LAN, and USB ports on the saddle to host an Intel NUC on the mount; a NUC chassis thinner than 38 mm fits.

Choose Your CEM70: A Version for Every Imaging Rig

All CEM70 versions share the same 31.8 kg payload, 13.6 kg head weight, iPolar, GPS, Go2Nova controller, 9.5 kg counterweight, and hard case. To choose the right one, first select a tracking family, then the connectivity that matches your workflow.

• CEM70: PPEC with < ±5 arcsec periodic error. Available in standard, WiFi/USB3 (W), iGuider (G), and NUC-Ready (N) configurations.
• CEM70EC: Adds a high-resolution RA encoder with RPEC for < 0.3 arcsec RMS periodic error. Available in standard, WiFi/USB3 (W), and NUC-Ready (N) configurations.
• CEM70EC2: Adds a second high-resolution encoder on the DEC axis for dual-axis RPEC. Available in standard, WiFi/USB3 (W) and NUC-Ready (N) configurations.