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iOptron GEM28 Mount

by iOptron
SKU IOP-G282B3
Original price CA$1,887.00 - Original price CA$4,521.00
Original price
CA$2,449.00
CA$1,887.00 - CA$4,521.00
Current price CA$2,449.00
Price Match Policy!
  • 28 lbs (12.7 kg) instrument payload capacity
  • 10 lbs (4.5 kg) mount head weight
  • Payload-to-weight ratio of 2.80
  • Go2Nova® 8409 controller with ~212,000 object database
  • Integrated Wi-Fi and USB for computer control
  • ST-4 compatible autoguiding port
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty
  • iOptron GEM28 Mount

    The iOptron GEM28 Mount delivers an exceptional payload capacity of 28 lbs on a mount head that weighs a mere 10 lbs, achieving a payload-to-weight ratio of 2.80 for unmatched portability. Its 1.8º stepper motors provide a drive resolution of 0.17 arc-seconds for precise tracking, while the Go2Nova® 8409 hand controller puts a database of ~212,000 celestial objects at your fingertips with a maximum slew speed of 6º per second.

    A 2.80 Payload-to-Weight Ratio: 28 lbs on a 10 lb Frame

    The core design philosophy of the GEM28 is to maximize imaging capability while minimizing weight. The all-metal, CNC-machined structure houses robust Φ35mm steel axis shafts and large Φ55mm ball bearings, providing the rigidity needed to support a 28 lb payload without compromising stability. This class-leading 2.80 payload-to-weight ratio means you can carry a larger optical tube to a dark sky site without being burdened by an excessively heavy mount.

    144-Tooth Worm Gears and PPEC: Tracking Below ±12 Arcseconds

    Accurate tracking is driven by a synchronous belt transmission system connected to large, Φ88mm 144-tooth aluminum worm wheels on both axes. This system delivers smooth motion with a native periodic error of less than ±12 arcseconds. For imagers, the mount's Permanent Periodic Error Correction (PPEC) records and corrects the fundamental error of the worm gear, significantly improving unguided tracking and making autoguiding more precise.

    Integrated Wi-Fi and USB: Full ASCOM Control Out of the Box

    The GEM28 is built for the modern astrophotographer with both built-in Wi-Fi and a standard USB port. This allows for direct connection and control from a PC, laptop, or smart device without requiring extra adapters. Full ASCOM compatibility ensures seamless integration with popular imaging software suites, while a dedicated ST-4 autoguide port provides the connection needed for high-precision, long-exposure deep-sky imaging.

    iOptron GEM28 vs. Celestron Advanced VX: The Portability Advantage

    While the Celestron Advanced VX (AVX) is a respected workhorse with a slightly higher 30 lb payload, the iOptron GEM28 holds a decisive advantage in portability and modern features.

    • Mount Weight: The GEM28's head weighs only 10 lbs, a significant reduction compared to the AVX's 17 lbs. This makes the GEM28 far easier to transport and set up in the field.
    • Payload Ratio: With a 2.80 payload-to-weight ratio, the GEM28 is engineered for efficiency, carrying more instrument weight per pound of mount.
    • Connectivity: The GEM28 includes built-in Wi-Fi as a standard feature, offering wireless control that typically requires an optional accessory on competing mounts.
  • What is the real-world imaging payload of the iOptron GEM28?

    The iOptron GEM28 has a stated payload of 28 lbs (12.7 kg). For astrophotography, a common rule is to stay at 50-60% of the visual payload. However, due to its rigid design, many users successfully image with setups weighing up to 18-20 lbs, provided the telescope is well-balanced and protected from wind.

    Does the iOptron GEM28 have built-in Wi-Fi for control?

    Yes, the iOptron GEM28 features built-in Wi-Fi. This allows you to control the mount wirelessly using software on your smartphone, tablet, or computer, eliminating the need for a separate Wi-Fi dongle.

    What does Permanent PEC (PPEC) do on the iOptron GEM28?

    Permanent Periodic Error Correction (PPEC) is a feature that analyzes and records the inherent mechanical errors in the mount's worm gear. Once recorded, the GEM28's firmware constantly applies corrections to counteract this error, resulting in smoother, more accurate tracking. This is particularly beneficial for unguided imaging or to improve the performance of an autoguider.

    Can the iOptron GEM28 handle an 8" SCT like a Celestron C8 for astrophotography?

    Yes. A typical 8" SCT optical tube weighs around 12-13 lbs, which is well within the 28 lb payload capacity of the iOptron GEM28. However, an SCT has a long focal length, which magnifies any tracking errors. For successful long-exposure imaging of targets like Jupiter or the Orion Nebula (M42), using an autoguider through the mount's ST-4 port is highly recommended for the sharpest results.

    Is the iOptron GEM28 a good choice for a portable setup with a wide-field refractor?

    The iOptron GEM28 is an excellent choice for this application. Its low 10 lb mount head weight and high payload capacity make it ideal for a "grab-and-go" imaging rig. Paired with a compact refractor, you can easily transport the entire setup to a dark sky location to capture large targets like the Andromeda Galaxy (M31) or the North America Nebula (NGC 7000).

    What's the difference between the iPolar and AccuAlign options for the iOptron GEM28?

    These are two different systems for polar alignment available with the iOptron GEM28.

    • AccuAlignTM: This is a traditional optical polar scope built into the mount's RA axis. It features a dark-field illuminated reticle that you align with Polaris (in the Northern Hemisphere) to achieve polar alignment.
    • iPolarTM: This is an integrated electronic polar scope (a small camera) that connects to a PC. It provides a live view of the sky near the pole and guides you through a simple software routine to achieve a highly accurate alignment, even if Polaris is not visible.
  • Mount Type German Equatorial Mount
    Payload Capacity 28 lbs (12.7kg), excluding counterweight
    Mount Weight 10 lbs (4.5kg)
    Payload to Mount Weight Ratio 2.80
    Structure Material All metal, Casting + CNC machined
    Periodic Error (PE) <±12 arcsec
    Periodic Error Correction (PEC) Yes, Permanent PEC
    Worm Wheels (RA & Dec) Φ88mm, 144 teeth, aluminum
    Axis Shafts (RA & Dec) Φ35mm steel
    Bearings (RA & Dec) Φ55mm ball bearing
    Worm Gears Φ15.2mm, Brass
    Motor Drive 1.8º stepper motor, 128X microdivision
    Drive Resolution 0.17 arc seconds
    Transmission Synchronous belt
    Hand Controller Go2Nova® 8409
    Object Database ~212,000 objects
    Slew Speeds 1×, 2×, 8×, 16×, 64×, 128×, 256×, 512×, MAX (6º/sec)
    Latitude Adjustment Range 10º ~ 70º
    Azimuth Adjustment Range ± 6º
    Polar Scope AccuAlign TM optical polar scope (model dependent)
    Dovetail Saddle 3.8" Vixen-style, center adjustable
    Counterweight 10 lbs (4.5kg)
    Counterweight Shaft Φ20 x 200mm, Stainless Steel
    Shaft Extension Φ20 x 120mm, Stainless Steel
    Tripod LiteRoc heavy-duty stainless steel tripod (model dependent)
    Connectivity Built-in Wi-Fi and USB port
    Autoguide Port Yes (ST-4 compatible)
    PC Control Yes (ASCOM)
    Power Requirement 12V DC, 5A
    Power Consumption 0.6A (Tracking), 0.9A (GOTO)
    AC Adapter 100V ~ 240V (included)
    Carrying Case Included (model dependent)
    Operating Temperature -10ºC ~ 40ºC
  • iOptron 2-Year Telescope Mount Warranty