The CEM70ECW combines the three things that make the CEM70 platform especially interesting for a serious imaging system: substantial payload capacity, encoder-corrected RA tracking, and a more capable through-mount connection system.
It carries up to 70 lb (31.8 kg) of telescope and imaging equipment, excluding counterweights, on a mount head that weighs 30 lb (13.6 kg). That gives it enough capacity for larger SCTs, substantial refractors, Ritchey-Chrétiens, and complex imaging trains without moving all the way to the size and weight of the CEM120 observatory platform.
The ECW version adds a high-precision encoder on the right-ascension axis and uses iOptron's Real-Time Periodic Error Correction to continuously correct the repeating error of the RA worm drive. iOptron specifies encoder-corrected periodic error below 0.3 arcsecond RMS, measured on the bench over the mount's 348-second worm period.
It then adds built-in Wi-Fi and USB 3.0 through the mount. A USB 3.0 input at the rear of the RA axis connects the computer to the mount, internal iPolar, and three powered USB 3.0 ports near the saddle. Built-in Wi-Fi provides another option for communicating with and controlling the mount. If you want the RA encoder of the CEM70EC together with the more capable connection system of the CEM70W, this is the version that combines them.
Key Features
-
70 lb payload capacity. iOptron rates the CEM70ECW for up to 31.8 kg (70 lb) of telescope and imaging equipment, excluding counterweights.
-
30 lb mount head. A relatively manageable head for a mount in this payload class.
-
Center-Balanced Equatorial design. iOptron's CEM layout places more of the combined mount and payload mass directly over the tripod or pier.
-
High-precision RA encoder. Encoder feedback monitors the right-ascension axis while the mount tracks.
-
Real-Time Periodic Error Correction. The ECW continuously corrects the repeating RA worm error rather than relying on a conventional trained PPEC curve.
-
Encoder-corrected PE below 0.3 arcsecond RMS. iOptron specifies this performance over the mount's 348-second worm period under bench measurement.
-
Built-in Wi-Fi. Provides a wireless communication option for controlling the mount.
-
USB 3.0 through the mount. A single USB 3.0 computer connection serves the mount, internal iPolar, and three powered USB 3.0 ports at the saddle.
-
Internal iPolar electronic polar scope. The polar-alignment camera is built into the RA axis and uses plate solving rather than requiring you to position Polaris on a traditional reticle.
-
151mm worm wheels on both axes. RA and DEC each use a 248-tooth worm wheel driven by a 21.2mm worm.
-
55mm steel axles and 80mm bearings. Substantial mechanical components support the CEM70's larger payload class.
-
Precision stepper motors. 128 micro-steps provide a specified motor resolution of 0.07 arcsecond.
-
Up to 3.75°/sec slewing. Maximum GoTo speed is approximately 900× sidereal.
-
Go2Nova 8410 hand controller. Provides an 8-line × 21-character display and iOptron's extensive GoTo database.
-
Built-in 32-channel GPS. Supplies UTC time and location information to the mount.
-
Automatic zero-position search. The mount can electronically locate its mechanical reference position.
-
Configurable meridian treatment. The mount can stop or automatically flip, with settings allowing up to 10° of travel past the meridian when clearance permits.
-
8-inch spring-loaded dual saddle. Accepts both Losmandy D and Vixen-style dovetail plates.
-
Through-mount power distribution. Multiple DC connections near the saddle help keep accessory wiring off the moving axes.
-
Hard carrying case included. Protects the 30 lb mount head during storage and transport.
- Two-year limited warranty.
What the RA Encoder Changes
A conventional worm-driven equatorial mount has periodic error because small variations in the worm and wheel repeat as the worm turns. The standard CEM70 can reduce that repeating component with Permanent Periodic Error Correction and conventional autoguiding.
The CEM70ECW handles the RA drive differently.
A high-precision encoder monitors the right-ascension axis while the mount is tracking. The control system uses that feedback for Real-Time Periodic Error Correction, continuously correcting the repeating RA worm error as it occurs.
iOptron specifies the result as less than 0.3 arcsecond RMS periodic error, measured with the encoder over one 348-second worm period.
That figure describes the performance of the encoder-corrected RA drive itself. It is not a promise that every imaging system will produce 0.3-arcsecond stars or 0.3-arcsecond guiding. Seeing, polar alignment, atmospheric refraction, telescope flexure, wind, and the rest of the imaging system remain outside the encoder's correction loop.
What the encoder does is remove much of the predictable repeating RA worm error before the rest of the system has to deal with it.
Do You Still Guide the CEM70ECW?
For demanding long-exposure astrophotography, particularly at longer focal lengths and smaller image scales, guiding remains a normal part of the imaging system.
The RA encoder is not intended to correct every possible source of image motion. Its job is to improve the tracking of the right-ascension axis and correct the periodic component of the worm drive.
A guider can still respond to movement caused by the complete telescope system and the sky above it.
We would not choose the CEM70ECW simply because you want to eliminate guiding. We would choose it because you want the mount itself to provide very tight RA tracking before guiding and the rest of the imaging system are taken into account.
RA Encoder, Not Dual Encoders
The CEM70ECW has a high-precision encoder on the right-ascension axis.
The published sub-0.3-arcsecond RMS periodic-error specification refers to encoder-corrected RA tracking. The CEM70ECW does not have an equivalent high-precision tracking encoder on the declination axis.
If your application specifically calls for high-resolution encoder feedback on both RA and DEC, the CEM70EC2W is the model designed for that role.
USB 3.0 Through the Mount
A larger imaging system can accumulate almost as many cables as pounds, and that is where the ECW connection system earns its place.
At the rear of the RA axis is a USB 3.0 input for the computer. That connection serves the mount itself, the internal iPolar camera, and the three-port powered USB 3.0 hub located near the saddle.
Cameras, guide cameras, filter wheels, focusers, and other compatible USB devices can therefore connect near the telescope rather than each requiring a separate long data cable running down across the moving axes.
The saddle area also provides a 12V DC output rated to 3A, along with two additional DC outputs supplied through the separate DC input at the rear of the RA axis. That allows both data and accessory power to be distributed much closer to the imaging equipment.
The result is not a completely cable-free system, but it can substantially reduce the number of cables that have to move with the telescope during slews and meridian flips.
What the Built-In Wi-Fi Does
The CEM70ECW also includes built-in Wi-Fi for wireless communication with the mount.
That is separate from the USB 3.0 imaging hub. The Wi-Fi connection provides wireless mount communication and control; the saddle-side USB 3.0 ports are connected through the physical USB 3.0 input at the RA axis.
In other words, Wi-Fi does not automatically turn the mount's USB hub into a wireless connection for a cooled camera or other high-speed USB device. If those devices are connected through the CEM70ECW's USB 3.0 hub, the hub still needs its USB 3.0 connection to the computer.
Actual Wi-Fi range will also depend on distance, walls, interference, and the surrounding network environment. For many setups it is a useful additional control option; a permanent remote observatory may still use its own dedicated wired or wireless network infrastructure.
Room for the Complete Imaging System
The advantage of a 70 lb payload rating is not necessarily putting a 70 lb optical tube on the saddle. It is having room for everything that turns a telescope into an imaging system.
A C11, large refractor, Ritchey-Chrétien, or similar telescope can gain considerable weight once the camera, filter wheel, focuser, rotator, reducer or corrector, off-axis guider, dew equipment, rings, dovetails, and cabling are installed. A side-by-side configuration adds still more.
The CEM70ECW gives those systems room to grow without treating every accessory as the last few pounds the mount can tolerate.
Payload weight is still only one part of choosing a mount. A compact telescope and a long telescope at the same weight do not place the same mechanical load on the axes. Tube length, diameter, center of gravity, wind exposure, focal length, and image scale all matter along with total weight.
iPolar Built Into the RA Axis
The CEM70ECW includes iOptron's iPolar electronic polar scope inside the mount.
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 then shows you how to adjust the mount's altitude and azimuth controls.
The pole star itself does not have to be visible. The camera still needs enough of the surrounding polar sky to solve successfully, but you do not have to identify Polaris or Sigma Octantis and position it on a reticle manually.
On the ECW, iPolar is accessed through the same USB 3.0 computer connection that serves the mount and saddle-side USB hub.
Transportable Without Being a Small Mount
A 30 lb mount head is not grab-and-go, but it remains very different from an observatory-class mount head approaching 60 pounds before counterweights or telescope are added.
The CEM70ECW can live on a backyard or observatory pier and still be moved when you want to take a larger imaging system somewhere darker. The included hard case protects the head during storage and transportation, while the tripod and counterweights remain separate pieces.
A complete CEM70ECW system carrying a large telescope can still become substantial equipment. We would describe it as transportable rather than lightweight. The important point is that choosing encoder-corrected tracking, USB 3.0, Wi-Fi, 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. The CEM70 can also be installed on an appropriate Tri-Pier or permanent pier.
With a mount capable of carrying 70 lb of telescope equipment, the structure underneath it is part of the imaging system. Choose the support for the complete installed telescope rather than the mount head alone.
Counterweights
The CEM70ECW includes one 20 lb (9.5 kg) counterweight and a 28mm × 415mm stainless-steel counterweight shaft.
One counterweight is enough 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 CEM70ECW Center-Balanced Equatorial mount head
- High-precision RA encoder with Real-Time Periodic Error Correction
- 1x Internal iPolar electronic polar scope
- Built-in Wi-Fi
- USB 3.0 through-mount connection and three-port saddle-side USB 3.0 hub
- 1x 8-inch spring-loaded Losmandy D / Vixen dual saddle
- 1x Go2Nova 8410 hand controller
- 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 CEM70ECW 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 CEM70ECW mount head weighs 30 lb (13.6 kg).
What is the difference between the CEM70EC and CEM70ECW?
They share the same basic CEM70 mechanical platform, 70 lb payload rating, high-precision RA encoder, and Real-Time Periodic Error Correction. The ECW adds built-in Wi-Fi and USB 3.0 through the mount with three powered USB 3.0 ports near the saddle.
What is the difference between the CEM70W and CEM70ECW?
Both include Wi-Fi and USB 3.0 through the mount. The CEM70ECW additionally includes the high-precision RA encoder and Real-Time Periodic Error Correction. The CEM70W uses the standard non-encoder CEM70 tracking system.
What is the periodic-error specification?
iOptron specifies encoder-corrected periodic error below 0.3 arcsecond RMS, measured on the bench over the mount's 348-second RA worm period.
Does the CEM70ECW use PEC?
It uses iOptron's Real-Time Periodic Error Correction, or RPEC, in conjunction with the high-precision RA encoder rather than the conventional trained PPEC system used by the standard non-encoder CEM70.
Can I image unguided with the CEM70ECW?
The RA encoder can make unguided imaging more practical in some combinations of focal length, image scale, exposure time, and polar alignment, but it does not correct every source of image motion. For demanding long-exposure imaging, particularly at longer focal lengths, guiding remains a normal part of the system.
Does the RA encoder correct polar-alignment error?
No. It corrects the behavior of the RA tracking drive. It does not physically correct a misaligned polar axis, atmospheric refraction, telescope flexure, seeing, or wind.
Does the CEM70ECW have an encoder on DEC?
No. Its high-precision tracking encoder is on the RA axis. The CEM70EC2W is the version with high-precision encoders on both RA and DEC.
Does the CEM70ECW 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. The camera still requires enough of the surrounding polar sky for its plate solve to succeed.
What does the USB 3.0 connection handle?
The USB 3.0 input at the RA axis provides the computer connection for the mount, internal iPolar, and three powered USB 3.0 ports near the saddle.
Can the USB 3.0 hub send my camera images over the mount's Wi-Fi?
No. The Wi-Fi and USB 3.0 systems serve different purposes. Wi-Fi provides wireless mount communication. Devices connected to the saddle-side USB 3.0 hub communicate through the physical USB 3.0 input on the RA axis.
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 CEM70ECW 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 imaging installations.
CEM70ECW or CEM70EC2W?
The CEM70ECW provides the high-precision encoder on RA, where periodic worm error occurs during tracking. The CEM70EC2W adds high-precision encoder feedback on DEC as well. Choose the EC2W when your application specifically benefits from encoder feedback on both axes.
Final Thoughts
The CEM70ECW takes the CEM70 platform in two directions at once.
The high-precision RA encoder and Real-Time Periodic Error Correction improve the tracking system itself, reducing the repeating RA worm error to less than 0.3 arcsecond RMS under iOptron's bench measurement. At the same time, USB 3.0 through the mount and built-in Wi-Fi make a complex imaging system easier to connect and control.
Underneath those features is still the reason the CEM70 family exists: 70 lb of payload capacity on a 30 lb head that can live on a pier without becoming permanently tied to it.
If you want the RA encoder of the CEM70EC and the USB 3.0/Wi-Fi connection package in the same transportable CEM70 platform, that is the reason to choose the CEM70ECW.
