As an imaging system grows, the mount usually reaches its limit before the telescope does. A larger optical tube may be only the beginning; add rings, dovetails, a camera, filter wheel, electronic focuser, off-axis guider, reducer or corrector, dew equipment, and perhaps a second telescope, and a system that started comfortably on a mid-size mount can become a very different load.
The iOptron CEM70 is built for that next step. 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 considerably more capacity than a typical mid-size imaging mount without moving all the way to the size and weight of the CEM120 observatory platform.
The CEM70 is also designed around astrophotography rather than simply payload capacity. An internal iPolar electronic polar scope handles camera-based polar alignment, Permanent Periodic Error Correction helps reduce the repeating component of RA tracking error, through-mount power and USB connections simplify the imaging train, and automatic zero-position sensing gives the mount a repeatable mechanical reference at startup.
This is the standard CEM70 with internal iPolar and USB 2.0 connectivity. It does not use the high-resolution tracking encoder found on the EC versions, and it does not include the Wi-Fi and USB 3.0 features found on other CEM70 configurations. If you plan to guide your imaging system and want the mechanical capacity of the CEM70 platform without paying for features you may not need, this is the straightforward version.
Key Features
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70 lb payload capacity. iOptron rates the CEM70 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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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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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.
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Periodic error below ±5 arcseconds. iOptron specifies native PE below ±5 arcseconds, measured on the bench over the 348-second RA worm period.
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Permanent Periodic Error Correction. A trained PEC curve can be stored in the mount and replayed to reduce the repeatable component of RA tracking error.
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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 iOptron's extensive GoTo database.
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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 cable management. Power and USB connections are available near the saddle so fewer cables have to cross 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.
Room for the Complete Imaging System
The real advantage of a 70 lb mount is not necessarily putting a 70 lb optical tube on it. It is having room for everything that turns a telescope into an imaging system.
A C11, large refractor, Ritchey-Chrétien, or similar telescope can pick up a surprising amount of weight once the camera, filter wheel, focuser, rotator, guider, corrector, dew equipment, dovetails, and other hardware are installed. A side-by-side system adds even more.
The CEM70 gives you space to build that complete system 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.
Tracking and Guiding
The standard CEM70 is a precision worm-driven equatorial mount rather than an encoder-corrected mount.
Both axes use 151mm diameter, 248-tooth worm wheels, while the RA drive has a 348-second worm period. iOptron specifies native periodic error below ±5 arcseconds for the standard CEM70.
Permanent Periodic Error Correction lets the mount store a correction for the repeating component of the RA worm error. For demanding long-exposure imaging, particularly as focal length and image scale increase, conventional autoguiding remains the normal approach.
That makes the standard CEM70 a sensible choice for imagers who already expect to guide. PPEC can reduce the predictable mechanical error while the guider responds to the remaining movement of the complete telescope, atmosphere, and imaging system.
If you want high-resolution encoder feedback and Real-Time Periodic Error Correction inside the mount, the encoder-equipped CEM70 versions are the step up from this model.
iPolar Built Into the RA Axis
The CEM70 includes iOptron's iPolar electronic polar scope inside the mount.
Instead of looking through an 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 place it on a reticle manually.
For a mount that travels, having the polar-alignment camera already inside the RA axis is especially convenient. There is no additional polar-scope camera to install or align each time you set up.
Built for an Imaging Train
As imaging systems get larger, cable management becomes part of the mount rather than an afterthought.
The standard CEM70 routes useful power and data connections through the mount to the telescope side. The cable-management system includes two 12V DC outputs rated to 3A, three USB 2.0 ports, DC input and output, iOptron's iPort connection, and a USB input that serves both the mount and internal USB hub.
That gives cameras and accessories connection points near the saddle instead of requiring every cable to hang from the telescope and cross the moving RA and DEC axes.
This C70A version uses USB 2.0 and does not have built-in Wi-Fi. Other CEM70 configurations are available if USB 3.0 or wireless mount control is important to your imaging system.
Transportable Without Being a Small Mount
A 30 lb mount head is not grab-and-go, but it is a very different proposition from an observatory mount that weighs close to 60 pounds before the counterweights or telescope are added.
The CEM70 can live on a backyard pier and still be moved when the occasion calls for darker skies. The included hard case protects the head during storage and transportation, and the mount separates from the tripod and counterweights in manageable pieces.
A complete CEM70 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 70 lb of mount capacity does not automatically commit the telescope to one permanent observatory.
Under the Night Sky
The CEM70 begins to earn its place when the telescope has enough aperture or focal length that the mount becomes part of image quality.
A C11 or other long-focal-length telescope can work smaller galaxies, planetary nebulae, globular clusters, and fine structures that remain tiny through a short refractor. A substantial refractor can carry a large-format camera and full imaging train while leaving useful mechanical margin. A side-by-side configuration can use the same clear night at two very different image scales.
Those systems also make proper polar alignment, balance, guiding, and a rigid support more important. The CEM70 gives you the mechanical capacity and tracking platform; the telescope and imaging train still have to be set up carefully enough to take advantage of it.
Tripod or Pier
The tripod or pier is sold separately.
iOptron pairs the CEM70 with its LiteRoc #8023ACC tripod for a transportable setup. A permanent or more substantial pier is also a natural choice for heavier telescopes, long focal lengths, or an imaging system that does not need to travel.
With a mount capable of carrying 70 lb of telescope equipment, the structure underneath it matters. Choose the support for the complete installed system rather than the mount head alone.
Counterweights
The CEM70 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 CEM70 Center-Balanced Equatorial mount head
- 1x Internal iPolar electronic polar scope
- 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 CEM70 carry?
iOptron rates the CEM70 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 CEM70 mount head weighs 30 lb (13.6 kg).
Is the CEM70 portable?
It is transportable rather than grab-and-go. The 30 lb head and included hard case make it practical to move between sites, but a complete setup with tripod, counterweights, telescope, and imaging equipment can still be substantial.
Does this CEM70 include iPolar?
Yes. This version includes iOptron's internal iPolar electronic polar scope.
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 is the periodic error?
iOptron specifies native periodic error below ±5 arcseconds, measured on the bench over the mount's 348-second RA worm period.
Does the CEM70 have PEC?
Yes. The standard CEM70 supports Permanent Periodic Error Correction.
Does the CEM70 need guiding?
For demanding long-exposure astrophotography, especially at longer focal lengths, guiding is the normal approach. The standard CEM70 does not have the high-resolution tracking encoder found on the EC versions.
Does this version have Wi-Fi?
No. This version uses USB 2.0 for computer communication. Other CEM70 configurations are available with Wi-Fi and USB 3.0.
Does this version have USB 3.0?
No. Its through-mount USB hub is USB 2.0. Choose one of the USB 3.0 CEM70 configurations if higher-speed through-mount USB is important to your equipment.
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 CEM70 require?
The mount uses 12V DC at up to 5A. iOptron lists typical mount 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. A pier is also an excellent choice for a heavier or permanent imaging installation.
CEM40, CEM70, or CEM120?
Choose around the complete imaging system, not just the bare optical tube. The CEM70 is the step up when you need substantially more capacity than a mid-size mount but still want a 30 lb head that can reasonably be transported. The CEM120 moves into a 115 lb payload class and is more naturally suited to a permanent installation.
Accessories
iOptron LiteRoc Tripod #8023ACC (sold separately): iOptron's matched transportable tripod option for the CEM70 family.
Additional 28mm Counterweight (sold separately): heavier telescope and imaging systems may require more counterweight than the included 20 lb weight provides.
Off-Axis Guider and Guide Camera (sold separately): particularly useful with longer-focal-length telescopes because the guider sees motion through the main optical system rather than through a separate guide scope.
Final Thoughts
The CEM70 fills the space between a mid-size imaging mount and a full observatory-class system.
Its 70 lb payload gives larger telescopes and more complex imaging trains room to grow, while the 30 lb head and included hard case preserve the option of taking that capacity somewhere else. Internal iPolar, Permanent PEC, automatic zero-position sensing, GPS, through-mount cabling, and the dual saddle make it a mount designed around the realities of astrophotography rather than payload capacity alone.
If your imaging system has outgrown the mount underneath it but you are not ready to make the telescope a permanent fixture on one pier, that is where the CEM70 makes sense.
