The CEM70EC2W takes the CEM70 platform about as far as you can go without moving into a larger mount class. It carries up to 70 lb (31.8 kg) of telescope and imaging equipment on a mount head that weighs 30 lb (13.6 kg), then adds high-resolution encoders on both axes, dual-axis Real-Time Periodic Error Correction, built-in Wi-Fi, and USB 3.0 through the mount.
That combination makes it especially interesting for larger and more demanding imaging systems. The encoders give the mount direct positional feedback on both RA and DEC, while the USB 3.0 hub moves camera and accessory connections up to the saddle instead of forcing a bundle of data cables across the moving axes. Built-in Wi-Fi provides another way to communicate with and control the mount.
Internal iPolar handles camera-based polar alignment, GPS supplies time and location information, automatic zero-position sensing gives the mount a repeatable mechanical reference, and the 8-inch spring-loaded saddle accepts both Losmandy D and Vixen-style dovetails.
It is still a CEM70 at heart: serious imaging capacity on a 30 lb head that can live on a pier without being permanently tied to one.
Key Features
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70 lb payload capacity. iOptron rates the CEM70EC2W for up to 31.8 kg (70 lb) of telescope and imaging equipment, excluding counterweights.
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30 lb mount head. A relatively manageable head for a mount in this payload class.
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High-resolution encoders on both axes. Direct encoder feedback is provided on both RA and DEC.
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Dual-axis Real-Time Periodic Error Correction. iOptron uses the encoder system for real-time correction rather than a conventional trained PPEC curve.
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Encoder-corrected PE below 0.3 arcsecond RMS. iOptron specifies this measurement over the mount's 348-second worm period under bench testing.
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Built-in Wi-Fi. Provides wireless communication and mount control from compatible software and devices.
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USB 3.0 through the mount. One USB 3.0 input at the RA axis feeds the mount, internal iPolar, and three USB 3.0 ports near the saddle.
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Internal iPolar electronic polar scope. The polar-alignment camera is installed inside the RA axis and uses plate solving rather than requiring you to position Polaris on a traditional reticle.
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Center-Balanced Equatorial design. iOptron's CEM layout places more of the combined mount and payload mass directly over the tripod or pier.
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151mm worm wheels on both axes. RA and DEC each use a 248-tooth worm wheel driven by a 21.2mm worm.
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55mm steel axles and 80mm bearings. Substantial mechanical components support the CEM70's larger payload class.
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Precision stepper motors. 128 micro-steps provide a specified motor resolution of 0.07 arcsecond.
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Up to 3.75°/sec slewing. Maximum GoTo speed is approximately 900× sidereal.
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Go2Nova 8410 hand controller. Provides an 8-line × 21-character display and built-in heater.
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Built-in 32-channel GPS. Supplies UTC time and location information to the mount.
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Automatic zero-position search. The mount can electronically locate its mechanical reference position.
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Configurable meridian treatment. The mount can stop or automatically flip, with settings allowing up to 10° of travel past the meridian when clearance permits.
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8-inch spring-loaded dual saddle. Accepts both Losmandy D and Vixen-style dovetail plates.
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Through-mount power distribution. DC connections near the saddle help reduce the number of accessory cables crossing the moving axes.
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Hard carrying case included. Protects the 30 lb mount head during storage and transport.
- Two-year limited warranty.
Why Two Encoders?
A worm-driven equatorial mount has repeating mechanical errors associated with the worm and wheel. On the standard CEM70, Permanent Periodic Error Correction and conventional guiding are used to reduce that repeating component.
The CEM70EC2W adds high-resolution encoder feedback on both axes.
On RA, the encoder allows the mount to monitor and correct the repeating tracking error produced by the worm drive in real time. iOptron specifies encoder-corrected periodic error below 0.3 arcsecond RMS over the 348-second worm period.
The second high-resolution encoder provides equivalent positional feedback on the declination axis. iOptron describes the EC2 system as providing dual-axis Real-Time Periodic Error Correction.
That is the fundamental difference between the EC2W and the single-encoder CEM70ECW.
What the Encoders Don't Do
The encoder system improves the mount's knowledge and control of its own axes. It does not directly measure every source of motion seen by the imaging camera.
Polar-alignment error, atmospheric refraction, seeing, wind, differential flexure, and movement elsewhere in the optical system remain outside the encoder itself.
For demanding long-exposure astrophotography, especially at longer focal lengths and smaller image scales, guiding can therefore remain useful.
The reason to choose the EC2W is not that guiding becomes unnecessary. It is that the mount has high-resolution positional feedback on both axes and handles more of its own tracking behavior internally before the guider has to respond.
USB 3.0 Through the Mount
A large imaging system can accumulate almost as many cables as pounds. The CEM70EC2W moves much of that connection point up to the telescope.
A USB 3.0 input at the RA axis connects the imaging computer to the mount's internal USB system. Three USB 3.0 ports near the saddle provide connection points for compatible cameras, guide cameras, focusers, filter wheels, and other USB devices.
Instead of running several long USB cables from the telescope down past the RA and DEC axes, those devices can connect near the saddle and share the through-mount USB path.
The saddle area also provides a 12V DC output rated to 3A and additional DC pass-through connections for accessory power.
The result is not a cable-free telescope, but it can make a complex imaging train considerably cleaner and easier to route through large slews and meridian flips.
What the Built-In Wi-Fi Does
The CEM70EC2W also includes built-in Wi-Fi for wireless communication with the mount.
That is separate from the USB 3.0 imaging path.
Wi-Fi provides wireless mount communication and control. Devices connected to the saddle-side USB 3.0 hub communicate through the physical USB 3.0 input at the RA axis.
In other words, the built-in Wi-Fi does not make a cooled camera or other USB accessory wireless. If your imaging equipment is connected through the mount's USB 3.0 hub, that hub still needs its USB connection to the imaging computer.
Actual wireless range depends on distance, walls, interference, and the surrounding network environment.
Room for the Complete Imaging System
The usefulness of a 70 lb payload rating is not necessarily putting a 70 lb optical tube on the saddle. It is having room for the complete system.
A C11, large refractor, Ritchey-Chrétien, or similar telescope can gain substantial weight once you add rings, dovetails, a cooled camera, filter wheel, electronic focuser, rotator, reducer or corrector, off-axis guider, dew equipment, and cabling.
The CEM70EC2W gives those systems room to grow without immediately moving into the much larger CEM120 class.
Total weight is still only part of mount selection. Tube length, diameter, center of gravity, wind exposure, focal length, and image scale all affect how demanding a telescope will be on the mount.
iPolar Built Into the RA Axis
The CEM70EC2W includes iOptron's iPolar electronic polar scope inside the RA axis.
Instead of looking through a traditional optical polar scope, you connect the iPolar to a supported computer and let the software plate-solve the surrounding polar star field. It determines where the RA axis is pointing relative to the true celestial pole and shows you how to adjust the mount's altitude and azimuth controls.
The pole star itself does not have to be visible. Enough surrounding polar sky still needs to be available for the camera to solve successfully, but you do not have to identify Polaris or Sigma Octantis and place it manually on a reticle.
Transportable Without Being a Small Mount
A 30 lb mount head is not grab-and-go, particularly once a large telescope and counterweights are added. But it remains much easier to move than an observatory-class head approaching 60 pounds by itself.
The CEM70EC2W can live on a backyard or observatory pier and still be transported when you want to take a larger imaging system somewhere darker. The included hard case protects the head during storage and transportation, while the support, counterweights, and telescope travel separately.
We would describe it as transportable rather than lightweight. The important point is that choosing dual encoders and a 70 lb payload does not automatically commit the mount to one permanent installation.
Tripod or Pier
The tripod or pier is sold separately.
iOptron lists the LiteRoc #8023ACC as a matched tripod for the CEM70 family. An appropriate Tri-Pier or permanent pier is also an option, particularly for heavier or permanent imaging systems.
With a mount capable of carrying 70 lb of telescope equipment, the support underneath it becomes part of the imaging system. Choose the tripod or pier for the complete installed telescope rather than the mount head alone.
Counterweights
The CEM70EC2W includes one 20 lb (9.5 kg) counterweight and a 28mm × 415mm stainless-steel counterweight shaft.
One counterweight is sufficient for many moderate telescope configurations, but heavier systems can require additional counterweight to achieve proper RA balance. The amount needed depends on the complete payload and its center of gravity.
Additional compatible 28mm counterweights are sold separately.
What's Included
- 1x iOptron CEM70EC2W Center-Balanced Equatorial mount head
- High-resolution encoders on RA and DEC
- Dual-axis Real-Time Periodic Error Correction
- 1x Internal iPolar electronic polar scope
- Built-in Wi-Fi
- USB 3.0 through-mount connection with three saddle-side USB 3.0 ports
- 1x 8-inch spring-loaded Losmandy D / Vixen dual saddle
- 1x Go2Nova 8410 hand controller with built-in heater
- 1x 28mm × 415mm stainless-steel counterweight shaft
- 1x 20 lb (9.5 kg) counterweight
- 1x Hard carrying case
- 1x 12V/5A AC adapter for indoor use
- Mount connection accessories
Not included: tripod or pier, additional counterweights.
Frequently Asked Questions
How much can the CEM70EC2W carry?
iOptron rates it for up to 70 lb (31.8 kg) of payload, excluding counterweights. Telescope length, diameter, center of gravity, focal length, and imaging requirements should be considered along with total weight.
How much does the mount head weigh?
The CEM70EC2W mount head weighs 30 lb (13.6 kg).
Does it really have encoders on both axes?
Yes. The CEM70EC2W uses high-resolution encoders on both RA and DEC, and iOptron specifies dual-axis Real-Time Periodic Error Correction.
What is the periodic-error specification?
iOptron specifies encoder-corrected periodic error below 0.3 arcsecond RMS, measured on the bench over the 348-second RA worm period.
CEM70ECW versus CEM70EC2W — what's the difference?
Both share the 70 lb CEM70 platform, RA encoder, Wi-Fi, USB 3.0, and internal iPolar. The EC2W adds a second high-resolution encoder on DEC and dual-axis encoder feedback.
Can I image unguided?
The dual-encoder system can make unguided operation more practical in some combinations of focal length, exposure time, image scale, and polar alignment, but it does not correct every source of image motion. For demanding long-exposure imaging, especially at longer focal lengths, guiding can remain useful.
Does the CEM70EC2W include iPolar?
Yes. iOptron's internal iPolar electronic polar scope is installed in the RA axis.
Does iPolar require Polaris to be visible?
No. Polaris itself does not have to be visible. Enough surrounding polar sky still needs to be available for the camera to plate-solve successfully.
What does the built-in Wi-Fi control?
Wi-Fi provides wireless communication with the mount for GoTo, tracking, and compatible control software. It does not wirelessly carry data from cameras attached to the USB 3.0 hub.
What does the USB 3.0 connection handle?
The USB 3.0 input at the RA axis connects the imaging computer to the mount's internal USB system and three USB 3.0 ports near the saddle.
Can my camera send images over the mount's Wi-Fi?
No. USB devices connected to the saddle-side hub communicate through the physical USB 3.0 input on the RA axis. Wi-Fi and the USB imaging hub are separate systems.
CEM70EC2W versus CEM70EC2-NUC — which should I choose?
Both use the CEM70 platform and high-resolution encoders on both axes. The EC2W emphasizes built-in Wi-Fi and USB 3.0 through the mount. The EC2-NUC is designed around mounting a compatible mini PC directly at the saddle with dedicated power, Ethernet, and USB pass-through. Choose according to where you want the imaging computer to live.
How many counterweights are included?
One 20 lb (9.5 kg) counterweight is included. Heavier telescope systems may require one or more additional counterweights.
What dovetail plates fit the saddle?
The 8-inch spring-loaded dual saddle accepts both Losmandy D and Vixen-style dovetail plates.
What power does the CEM70EC2W require?
The mount uses 12V DC at up to 5A with a 5.5mm/2.5mm connector. iOptron lists typical consumption at approximately 0.6A while tracking and 0.8A during GoTo. A 12V/5A AC adapter intended for indoor use is included.
What tripod should I use?
iOptron lists the LiteRoc #8023ACC as a matched tripod for the CEM70 family. An appropriate Tri-Pier or permanent pier is also an option for heavier or permanent installations.
Final Thoughts
The CEM70EC2W combines the CEM70 features that matter most to a demanding imaging system in one mount.
High-resolution encoders on both axes and dual-axis RPEC address the tracking system itself. USB 3.0 through the mount gives cameras and accessories a cleaner data path near the saddle. Built-in Wi-Fi provides wireless mount control, while internal iPolar, GPS, automatic zero search, and the dual saddle handle the rest of the setup.
Underneath all of that is still the part that makes the CEM70 family unusual: 70 lb of payload capacity on a 30 lb head that can live on a permanent pier and still go into a hard case when you want to take it somewhere else.
If you want dual high-resolution encoders together with Wi-Fi and USB 3.0 in the transportable CEM70 platform, that is the reason to choose the CEM70EC2W.
