Precision Mount Performance in a Travel-Friendly Package
The iOptron GEM28 G282B1 offers serious equatorial mount performance in a surprisingly compact and lightweight system. Designed for portable astrophotography setups and mobile visual observers, this version includes the AccuAlign™ illuminated polar scope, a standard 1.5" stainless steel tripod, and a fitted hard case for the mount head. Its precision belt-drive system, built-in Wi-Fi, and industry-leading Go2Nova hand controller make it a favorite for those upgrading from star trackers or seeking a lightweight GoTo mount that doesn’t compromise on capability.
iOptron's compact next-generation GEM28 mount is a tiny titan with a 28 pound payload capacity.
This iOptron Gem28 German equatorial mount has:
-
German equatorial design, latitude range of 10° ~ 70°
-
Ideal for both visual observation and astrophotography
-
Low periodic error (< ± 12 arc seconds)
-
Payload of 12.7 kg (28 lbs) with the mount-only weight of 4.5 kg (10 lbs)
-
CNC machined and cast metal body
-
Spring loaded gear system
-
Large easy to use quick-lock gear clutches
-
Stepper motor with low power consumption
-
AccuAlign™ calibrated polar scope
-
Polar alignment routine for those who can’t see the Pole Star
-
Go2Nova® 8409 controller with Advanced GOTONOVA® GOTO Technology
-
Integrated ST-4 autoguiding port
-
Built-in Wi-Fi
-
USB port for firmware upgrade and computer control
-
Standard 1.5 inch heavy-duty stainless steel tripod (5kg)
-
Die-cast metal tripod spreader with accessory tray
-
Hard carrying case
-
Optional 32-channel Global Positioning System (GPS)
-
Optional iGuider™ autoguiding system (#3360)
Payload Capacity:
The GEM28 comes with a 10 pound (4.5kg) counterweight, an 8" x 20mm counterweight shaft, and a 5" x 20mm counterweight shaft extension. These can be combined to support up to 28 pounds (12.7kg) of imaging gear. For most field astrophotography applications, we recommend limiting the payload to around 20 pounds for optimal performance.
Drive System Details:
The GEM28’s synchronous belt transmission includes 144-tooth, 88mm aluminum drive gears in both right ascension and declination. Brass worm gears and 30mm steel axis shafts deliver smooth motion and durability for long tracking runs.
Its dual-axis stepper motors with encoders offer 0.17 arcsecond step resolution. Tracking rates include sidereal, solar, lunar, King, and user-defined. Backlash compensation is built in and user-adjustable. The system supports:
-
Guiding speeds: Sidereal and 2x sidereal
-
Centering speeds: 8x to 128x
-
Slewing speeds: 256x to 512x, with a max of ~4°/sec
The GEM28 includes an AC adapter, RS232 cable, and port for firmware updates and ASCOM-compatible control. A strain-relief cable protector is standard to help prevent accidental disconnections in the field.
GoToNova Hand Controller:
The Go2Nova 8409 hand controller features:
-
212,000+ object go-to database
-
8-line, 21-character LCD screen
-
Red LED backlit buttons for night use
-
Integrated heater for cold-weather visibility
-
Built-in Wi-Fi for smartphone/tablet control
-
Support for firmware upgrades and ASCOM/INDI control
Catalogs include Messier, NGC, IC, UGC, MCG, Caldwell, Abell, Herschel, SAO, GCVS, plus solar system objects, named stars, double stars, comets, asteroids, and all 88 constellations.
Mount Details:
The mount head weighs only 10 lbs (4.5kg), making it ideal for transport. It includes a custom-fit hard case for safe storage and travel. With a payload-to-weight ratio of 2.80, it’s one of the most efficient portable equatorial mounts available today.
Altitude adjustment is smooth and precise with a large side-mounted knob, and the dual azimuth knobs allow ±6° of fine-tuning. The included AccuAlign™ LED-illuminated polar scope provides quick and precise polar alignment when Polaris or Sigma Octantis is visible.
Tripod:
The included adjustable-height tripod features:
-
1.5" stainless steel legs
-
Die-cast metal accessory tray with central brace
-
Total weight: 10.6 lbs (4.8kg)
-
Supports the GEM28 and payload securely
This tripod is best suited for users looking to keep their rig light and mobile—perfect for dark-sky trips or backyard setups.
Mounting:
The GEM28 includes a 3.8" Vixen-style dovetail saddle with a center-adjustable clamp, compatible with a wide range of telescope tubes used in entry-level and intermediate astrophotography setups.
If you're looking for a stable, high-precision, mid-capacity German equatorial mount—yet one that is reasonably portable and reasonably priced—take a careful look at the iOptron GEM28. It may be just what you are looking for.
Observing Tip:
Using the 1.5" tripod with the GEM28 is a great way to keep your gear lightweight and manageable—but be sure to fully extend only when needed. For best results, extend the legs only halfway and keep your scope balanced low to the ground. With proper alignment and a small refractor or imaging Newtonian, you can enjoy guided or even short unguided exposures at focal lengths up to 600mm under good seeing conditions.
Final Thoughts:
The GEM28 G282B1 is a serious mount for users who want a step above a star tracker without leaping into the weight and cost of observatory-class gear. Its AccuAlign polar scope, robust GoTo performance, and included 1.5" tripod and hard case make it a practical and powerful choice for grab-and-go setups, outreach events, or building your first dedicated astrophotography rig. Portable, precise, and packed with features—the G282B1 is ready to follow wherever your skies take you.
