iOptron CEM70G "center-balanced" go-to equatorial mount, with IGuider Optical Guider, without tripod

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The iOptron center-balanced CEM70G go-to German equatorial mount has a payload capacity of 70 pounds, yet the mount head (less counterweight) weighs only 27 pounds. Designed to give intermediate and advanced astrophotographers and visual observers both excellent performance and big scope capacity.
Our Product #: CEM70G
iOptron Product #: C70AG
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Product Description

This new iOptron CEM70 center-balanced German equatorial mount has:
70 pound maximum payload capacity
Standard IGuider onboard Optical Guiding System
Unique and very stable center-balanced design
Built-in dual-axis go-to computer drive with 359,000+ object database in Go2Nova Controller
Built-in 32-channel GPS
Permanent periodic error correction <+/-3.5 arcsec and ST-4 autoguider port
Standard Ipolar Electronic Polar Scope
Adjustable counterweight shaft for operation at latitudes from 0° to 70°
Dual Saddle, Losmandy and Vixen Style
Advanced Cable Management
Hard carry case for mount head
Standard Wifi

The iOptron CEM70G mount is a high payload capacity/high accuracy German equatorial mount that is well-suited to serious long-exposure astrophotography. The CEM70G's unique center-balanced design centers the combined weight of the payload and counterweight directly over the mount's center of gravity. This allows for greater natural stability than a conventional German equatorial mount.

The mount is extremely light compared to its payload capacity - a nice benefit when setting up at a remote site. The mount head weighs only 30 pounds (13.6 kg) without counterweight, yet it has a 70 pound (31.8 kg) payload capacity.

The adjustable counterweight shaft prevents the counterweight from getting in the way of the optional tripod or pier when operating at low latitudes (from 10° down to the equator). Polar aligning is quick and accessible at all times since the standard equipment illuminated polar scope is not blocked by the declination shaft.

The CEM70G mount is equipped with iOptron's most advanced go-to technology and a database of 359,000 objects, making the CEM70 one of the most powerful and accurate go-to mounts available. Other mount features include a magnetically-loaded gear system, gear switches on both R.A. and dec axes, a screw/worm type latitude adjuster, and a built-in cable management system.

The biggest news is the built in IGuider.  The iGuider is a built in, onboard, optical guider system.  The iGuider increases tracking accuracy and combines compents making a more portagle imaging platform.  

The CEM70G also comes standard with WiFi and USB 3.0.

With its supplied 100V ~ 240V AC and 12 VDC battery adapters, the iOptron CEM70G is designed for both backyard or observatory imaging, as well as transporting to a dark sky site. It is ideal for visual observing and long exposure astrophotography .

Payload capacity: The CEM70G comes with a 21 pound (9.5 kg) counterweight capable of balancing instrument payloads up to approximately 30-35 pounds (13.6 to 15.2 kg). An optional counterweight will be needed to balance heavier loads up to its rated 70 pound capacity. Most astrophotographers will probably want to limit the instrument payload to a maximum of about 40 pounds, to benefit from the increased stability of having a smaller instrument on an over-sized mount.

Drive system details: The CEM70G has 248-tooth 151mm diameter aluminum drive gears in both right ascension and declination. Brass worms are standard. Periodic error is ~+/-3.5 arc seconds peak to peak. Permanent perriodic error correction is standard. The drive uses a patent-pending non-contact magnetically loaded gear system. Gear switches in both RA and dec disengage the gears for easier load balancing,

The standard equipment dual-axis DC stepper motors with encoders use a temperature-compensated quartz crystal oscillator controller to provide 0.06 arc second per step resolution, assuring an imperceptible stepping motion during visual observing and imaging. User-adjustable backlash compensation is standard.

The DC motors require a 12VDC (9~15VDC) power supply capable of providing a 2A output. The motors draw 0.6A while tracking and 1.1A while slewing. There are nine guiding, centering, and slewing speeds available: sidereal and 2x sidereal for guiding; 8x, 16x, 64x, and 128x sidereal for centering; and 256x (1°/sec), 512x (2°/sec) sidereal, and a maximum speed of ~3.75°/sec for slewing. There are five user-selectable drive speeds: sidereal, solar, lunar, the King rate for imaging near the horizon, and a user-defined speed.

The iOptron CEM70G comes with an appropriately-sized universal 100V ~ 240VAC to 12VDC adapter. It also comes with a standard equipment 12VDC cigarette lighter plug cable for use with optional rechargeable 12VDC battery packs, such as the iOptron 8 amp hour PowerWeight battery/7 pound counterweight combination or the Celestron 17 amp hour Power Tank.

Hand control details: The supplied GoToNova technology computer hand control has a built-in 32-channel GPS for accurate time and location acquisition when aligning on the sky. It has a more than 359,000 object go-to database that includes: 60 named deep sky objects; 9 solar system objects; the 110 object Messier Catalog, the 7,840 object NGC Catalog; the 5,386 object IC Catalog; the 12,921 object UGC Catalog; the 30,642 object MCG Catalog; the 109 object Caldwell Catalog; the 4,076 object Abell Catalog; the 400 object Herschel Catalog; 15 comets; 195 named stars; 210 double stars; 116 asteroids; 38,528 GCVS variable stars; the 88 modern constellations with their names and more; 258,997 SAO catalog stars; plus 60 user-defined objects.

The GoToNova hand controller has an 8 line/21 character LCD display and backlit LED buttons, plus a red LED reading light on the back. It has a built-in heater for good LCD visibility at temperatures as low as -4° Fahrenheit (-20°C). Permanent periodic error correction (PPEC) for astrophotography is built in.

An ST-4 autoguiding port is built in. A serial port in the hand control, and a supplied RS232 to RJ9 serial cable, allows connection to a computer and the internet for firmware upgrades as well as mount control using optional ASCOM-compliant software.

The CEM70G has a pre-wired instrument panel/cable management system that allows you to connect your imaging gear without having wires or cables dragging all over the mount when it is slewing or tracking. The instrument panel has two 12VDC outlets for powering your CCD camera or electric focuser. There are four non-powered USB 2.0 ports with Type A connectors for connecting to accessories. A 6P6C port is included to bridge the guiding port or accessories with a 6P6C/6P4C plug. The input panel next to the polar scope includes a 12VDC power input (5A maximum), a USB 2.0 port with a Type B connector, and a 6P6C port. These USB input and output ports allow you to wire up connections inside the mount head to suit your individual requirements.

Mount details: The CEM70G's innovative center-balanced design mount puts the weight of the payload at the center of gravity, allowing greater natural stability and lighter weight - a nice benefit when setting up at a remote site. The equatorial head, not counting the standard equipment counterweight or tripod, weighs only 30 pounds (13.6 kg) for the highest payload to mount weight ratio in its category.

The mount is designed to operate in both northern and southern hemispheres at latitudes from 0° to 70°. Twin adjustment knobs in the base of the mount let you fine-tune the azimuth alignment on the pole over a +/-8° arc. When using the CEM70G mount at latitudes below 10°, a few simple adjustments of the unique variable position counterweight shaft lets you change the counterweight bar angle so the counterweight does not bump the tripod during use.

Optical tube mounting method: The spring-loaded mount head has an 8" dual saddle that accepts both industry-standard Losmandy "D-Plate" and Vixen-style dovetails.

No tripod or pier supplied: Because of the CEM70G's ability to be used with a variety of scope types in both observatory and in-the-field situations, no tripod is supplied. This allows the purchaser to chose from a variety of tripods and piers that best suits their needs.

If you're looking for a high-precision, high payload capacity German equatorial mount for serious astrophotography and visual observing - yet one that is portable and reasonably priced - take a careful look at the new iOptron CEM70G. It may be just what you are looking for.

  • Mount Type:     CEM (Center balanced EQ Mount).
  • Payload (excl. CW):     31.8 kg(70 lbs).
  • Mount Weight:     13.6 kg (30 lbs).
  • Payload/Mount Weight:     2.33.
  • Latitude Adjustment Range:     0~65°.
  • Azimuth Adjustment Range:     ±4°.
  • Tracking Accuracy (PE):     < ±3.5 arcsec.
  • Period:     348 sec.
  • Right Ascension Worm Wheel:     248 teeth, M=0.6, Ø151 mm.
  • Declination Worm Wheel:     248 teeth, M=0.6, Ø151 mm.
  • Worm:     Ø21.2 mm.
  • Right Ascension Axle:     Ø55 mm steel.
  • Declination Axle:     Ø55 mm. 
  • Right Ascension Bearings:     Ø80 mm. 
  • Declination Bearings:     Ø80 mm,  
  • Counterweight Shaft:     Ø28 x 415 mm (SS, 1.9kg). 
  • Counterweight:     9.5 kg x 1.
  • Mounting Base Diameter:    Ø152 mm.
  • Motor:     1.8° stepper motor w/128 micor-step.
  • Resolution:     0.07 arcsec.
  • Transmission:    Synchronous belt. 
  • Hand Controller:     Go2Nova 8407+;  8 line 21 character LCD.  
  • Power:     DC 12V, 5A. 
  • Power Consumption:     0.6A (tracking), 0.8A (GOTO). 
  • Polar Scope:     Internal electronic polar scope, iPolar. 
  • Meridian treatment:     Stop (0-10° pass), flip. 
  • Zero position:     Automatic zero search.  
  • Park position:     horizontal, vertical, current, alt/az input. 
  • Dovetail saddle:     8-inch L-style D, and V-style.  
  • Level Indicator:     YES. 
  • Slew speed:     3.75°/sec (900x) max. 
  • PEC:     Permanent PEC. 
  • Guiding Port:     ST-4.  
  • GPS:     YES. 
  • Operation temperature range:     -20°C ~ +45°C. 
  • Hard case:     YES.  
  • Pier/Tripod:     Optional LiteRoc tripod or pier.
  • Communication Port:     USB3.0, Wifi.  
  • Cable Management:    2xDC12V (3A),  3xUSB3.0,  1xDC in/2xDC out, iPort.     
  • Guiding scope/camera:     Built-in guiding scope and camera, iGuider.   

Tech Details

Weight 30 lbs.
Warranty 2 years


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