iOptron CEM40 Mount

A Center-Balanced Design for a 2.28 Payload-to-Weight Ratio

The core of the CEM40's design is its Center-Balanced Equatorial Mount architecture, which places the payload's center of gravity directly over the tripod or pier's central axis. This gives maximum payload with natural stability, resulting in a payload-to-weight ratio of 2.28.

The structure is all metal, CNC machined, with an anodized red and black finish.

40 lb Capacity on a 17.4 lb Mount Head

The CEM40 supports a maximum payload of 40 lb (18 kg), excluding counterweights, making it a versatile platform for a wide range of optical tubes. The standard mount head weighs just 17.4 lb (7.9 kg), while NUC-ready versions weigh 18 lb (8.2 kg), for a payload-to-weight ratio of 2.2.

Φ110mm Worm Wheels and a 400-Second Worm Period

Both the Right Ascension and Declination axes utilize large Φ110mm worm wheels with 216 teeth, driven by Φ17mm brass worms with a 400-second period.

• Zero Backlash Worm Wheels: Both worm wheels are zero backlash.
• Synchronous Belt Transmission: Power is transferred from the stepper motors (1.8º, 128x micro-step, 0.08 arcsec motor resolution) to the worms via a synchronous belt.
• Solid Shafts and Bearings: Both RA and DEC axes are built on robust Φ45mm steel shafts supported by large Φ68mm bearings,

< ±7.5 arcsec PE or < 0.3 arcsec RMS with RPEC

The CEM40 is available in two performance tiers to match your imaging requirements.

• CEM40 (Standard): Offers a native periodic error of less than ±7.5 arcseconds. It has Permanent Periodic Error Correction (PPEC).
• CEM40EC (High-Resolution Encoder): This version adds a high-resolution optical encoder to the Right Ascension axis. This encoder provides Real-time Periodic Error Correction (RPEC), correcting worm gear errors as they happen to deliver a periodic error of less than 0.3 arcseconds RMS.

Integrated iPolar for Alignment from 0° to 60° Latitude

Every CEM40 has the integrated iPolar electronic polar scope. You connect it to a computer with a USB cable at the rear of the RA axis and follow the iPolar software; it is simple and fast and helps accurate alignment even when the pole star is obscured.

The mount's mechanical design supports a wide latitude adjustment range from 0° to 60°, with a special counterweight shaft mounting below 10°. The azimuth adjustment range is ±6°.

Go2Nova Controller: 212,000+ Objects & 4.5°/sec Slewing

The included Go2Nova hand controller is your command center for navigating the night sky. Its 8-line, 21-character LCD provides detailed information, while the built-in database contains over 212,000 objects, with star identification. Once aligned, the mount can slew between targets at a maximum speed of 4.5° per second (1080x sidereal), quickly centering your next object.

Meridian treatment is stop (0-10° pass) and flip. A built-in heater keeps the LCD working at temperatures as low as -20ºC (-4ºF).

USB, ST-4 Guiding, and NUC-Ready Options

A USB port connects the mount to a computer for control through the iOptron ASCOM driver. Wi-Fi is external and optional (the iStarFi adapter, #7434). A standard ST-4 autoguiding port allows you to connect a guide camera for precise tracking corrections during long exposures.

For a fully integrated setup, the CEM40 NUC-ready versions are designed to carry an Intel NUC mini-PC directly on the mount. These models add DC 19V, LAN and USB pass-throughs for the NUC; a NUC thinner than 38 mm fits.

6-inch Dual Saddle with Integrated Power and Data Ports

The 6-inch long dovetail saddle securely holds your telescope, accepting both Losmandy D-style and Vixen V-style plates without needing adapters. Standard versions have cable management with DC 12V (3A), ST-4 and USB.

NUC versions expand on this with dedicated ports for DC 12V (3A), DC (5A), a GUIDE port, USB, and pass-throughs for DC 19V, LAN, and another USB connection specifically for the NUC.

12V DC Power with 0.6A Tracking Consumption

Designed for efficiency in the field, the CEM40 operates on a standard 12V DC, 5A power supply. Power consumption is 0.6A while tracking and 0.9A during GoTo.

An AC adapter (100V ~ 240V) is included for indoor use or when operating from a mains power source. The mount also features a power-down memory function, so the mount remembers its R.A. and DEC positions if power is lost, even while slewing; after power returns, Select and Slew to the same star and it continues tracking.

Multiple CEM40 Versions for Portable, Pier, and Integrated Setups

The CEM40 is offered in a variety of packages to suit your specific needs for support, transport, and performance. All versions share the same 40 lb payload capacity, integrated iPolar, GPS, and Go2Nova controller.

• Tripod Packages: Choose the 1.75" LiteRoc stainless steel tripod (7 kg) or the 1.5" stainless steel tripod (5 kg). Both packages include a 5 kg (11 lbs) counterweight.
• Case Versions: Case versions add a hard carrying case.
• iGuider Version: This package adds iOptron's iGuider, a guiding scope and camera built into the mount, plus a hard case for the head.
• NUC-Ready Versions: These models are configured to mount an Intel NUC mini-PC directly, with NUC-dedicated cable management.
• Head Only Versions: For users who already own a suitable tripod or plan to mount on a permanent pier, the head-only packages include the mount, iPolar, controller, and hard case, but do not include a tripod or counterweight; the mount uses the #8027 5 kg counterweight.

32-Channel GPS and Automatic Zero Search

Setting up in the field is faster and more accurate thanks to several automated features. A built-in GPS receiver provides your location, date and time to the Go2Nova hand controller.

The mount also features an automatic zero search function. At the start of a session, the mount can find its own mechanical zero position, providing a reliable and repeatable starting point for alignment and tracking.