iOptron CEM40 — 18 kg centre-balanced equatorial mount The iOptron CEM40 uses iOptron's centre-balanced equatorial (CEM) design, which places the mount's and payload's weight directly over the centre of the tripod or pier. The result is a mount weighing only 7.9 kg that carries up to 18 kg, excluding counterweights, making it a portable choice for both…
Manufacturer model: iOptron CEM40 (standard, current production) · Specifications checked against manufacturer data on 2026-11-03
The iOptron CEM40 uses iOptron's centre-balanced equatorial (CEM) design, which places the mount's and payload's weight directly over the centre of the tripod or pier. The result is a mount weighing only 7.9 kg that carries up to 18 kg, excluding counterweights, making it a portable choice for both visual observing and astrophotography.
An integrated iPolar electronic polar scope gives accurate polar alignment, even when Polaris is hidden. Large quick-lock levers engage the gears easily, even with gloves on.
The standard CEM40 uses a brass worm on 216-tooth, 110 mm worm wheels with zero backlash, driven by precision stepper motors through a synchronous belt. iOptron specifies periodic error under ±7.5 arcseconds over the 400-second worm period, with permanent periodic error correction (PPEC). The encoder-equipped CEM40EC, sold separately, achieves under 0.3 arcseconds RMS.
The Go2Nova 8410 hand controller has a 212,000+ object database with star identification and a built-in heater. The mount supports ASCOM computer control over USB, has an ST-4 autoguiding port and GPS, and accepts optional Wi-Fi. Integrated cable management carries 12 V, ST-4 and USB through the mount.
| Design | Centre-balanced equatorial (CEM) |
|---|---|
| Payload | 18 kg, excluding counterweight (OTA size dependent) |
| Mount weight | 7.9 kg |
| Latitude range | 0–60° (special counterweight-shaft mounting below 10°) |
| Azimuth adjustment | ±6° |
| Periodic error | Under ±7.5 arcsec (encoder-measured, 400 s); PPEC |
| Worm gears | 216 teeth, 110 mm, zero backlash; 17 mm brass worm |
| Axes | 45 mm steel shafts; 68 mm bearings |
| Motor resolution | 0.08 arcsec |
| Maximum slew | 4.5°/s (1080×) |
| Saddle | 6-inch Losmandy D and Vixen dual saddle |
| Counterweight shaft | 28 × 280 mm stainless steel |
| Mount base | 120 mm diameter |
| Hand controller | Go2Nova 8410, 212,000+ objects |
|---|---|
| Polar scope | Internal iPolar electronic polar scope |
| Ports | USB, ST-4; GPS; optional external Wi-Fi |
| Cable management | DC 12 V (3 A), ST-4, USB |
| Power | 12 V DC, 5 A (5.5/2.5 mm plug); 100–240 V AC adapter included, indoor use only |
| Consumption | 0.6 A tracking; 0.9 A GoTo |
| Computer control | ASCOM |
| Operating temperature | −10 to +40 °C |
| Warranty | Two-year limited |
iOptron CEM40 specifications · CEM40 instruction manual
Standard CEM40 (PPEC), not CEM40EC (encoder) or CEM40G (iGuider). Current-production spec used: 7.9 kg, 28 mm CW shaft, 6-inch dual saddle, Go2Nova 8410. Earlier production (7400 series) was 7.2 kg with 20 mm shaft and universal saddle; confirm supplied generation and package (head only / tripod / counterweight) before sale. Shop product has no SKU.
| Latitude range (°) | 0–60 |
|---|---|
| Azimuth adjustment (°) | ±6 |
| Periodic error | <±7.5 arcsec, PPEC |
| Worm period (s) | 400 |
| Axis shafts bearings | 45 mm steel; 68 mm bearings |
| Motor resolution (arcsec) | 0.08 |
| Max slew | 4.5 deg/s (1080x) |
| Cw shaft | 28 x 280 mm SS |
| Mount base (mm) | 120 |
| Hand controller | Go2Nova 8410, 212,000+ objects |
| Polar scope | Internal iPolar |
| Consumption | 0.6 A tracking; 0.9 A GoTo |
| Operating temperature (°C) | -10 to 40 |
| Warranty | Two-year limited |
Data sheet
iOptron CEM40 — 18 kg centre-balanced equatorial mount The iOptron CEM40 uses iOptron's centre-balanced equatorial (CEM) design, which places the mount's and payload's weight directly over the centre of the tripod or pier. The result is a mount weighing only 7.9 kg that carries up to 18 kg, excluding counterweights, making it a portable choice for both…
Manufacturer model: iOptron CEM40 (standard, current production) · Specifications checked against manufacturer data on 2026-11-03
