iOptron GEM28 Go-To German Equatorial Mount With iPolar, Hard Case, And Literoc Tripod
Manufacturer Part # G282A3
Manufacturer Part # G282A3
iOptron's compact next-generation GEM28 mount is a tiny titan with a 28 pound payload capacity.
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 hold the GEM28's maximum payload of 28 pounds (12.7kg). However, most astrophotographers will probably want to limit the instrument payload to a maximum of about 20 pounds, to benefit from the increased stability of having a smaller instrument on an over-sized mount.
Drive system details: The synchonous belt transmission of the GEM28 has a 144-tooth 88mm diameter drive gear in right ascension and a 144-tooth 88mm diameter drive gear in declination. Brass worm gears are standard. Both the right ascension axis and declination shaft are 30mm in diameter.
The standard equipment dual-axis stepper motors with encoders provide 0.17 arc second per step resolution, assuring an imperceptible stepping motion during visual observing and imaging. Available user-selected tracking rates include sidereal, solar, lunar, King, and a user-defined speed. User-adjustable backlash compensation is standard.
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 ~4°/sec for slewing.
The iOptron GEM28 comes with an AC adatper. It also comes with an RS232 cable and port for mount firmware upgrade and ASCOM control using an optional computer. Strain relief power cord cable protection is standard.
The supplied GoToNova technology computer hand control has a more than 212,000 object go-to database that includes: 60 named deep sky 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; 38,528 GCVS variable stars; the SAO catalog; 116 asteroids; the 88 modern constellations with their names and more; plus 60 user-defined objects.
Permanent periodic error correction (PEC) for astrophotography is built in. HBX ports are provided for an optional ST-4 type autoguider, a PC, and auxiliary components. It uses a new command set that is completely open for user-defined control of the mount. The mount also come with WiFi as standard equipment allowing the modern day user a multitude of ways to connect to the mount.
The GoToNova hand controller has the largest LCD screen on the market, with an 8 line/21 character display and backlit LED buttons. A heating mechanism in the hand control provides display visibility at a temperature as low as 4° Fahrenheit (-20°C), the lowest working temperature among commercially-available computer hand controls.
Mount details: The GEM28's mount is built to be strong, yet small and light, to satisfy both stability and portability needs. The equatorial head, not counting the standardequipment 10 pound (4.5kg) counterweight, weighs only 10 pounds (4.5kg) for the highest payload to mount weight ratio in its category (2.80).
The particular unit comes with a hard carrying case for the head as standard equipment.
The mount is designed to operate in both northern and southern hemispheres at latitudes from 10° to 70°. A large adjustment control between the vertical side pieces of the mount and an indicator window in one of the side pieces makes it easy to align the mount on the celestial pole in altitude. Twin adjustment knobs in the base of the mount let you fine-tune the azimuth alignment on the pole over a +/-6° arc.
The GEM28A mount has an integrated electronic polar finder scope known as the iPolar. This tool ensures the accurate alignment of a telescope, even when the pole star is obscured. There is a built-in bubble level for leveling the mount for the most accurate tracking.
Tripod: The supplied LiteRoc adjustable height tripod has 1.75" diameter stainless steel legs. It is very solid and stable, able to support the GEM28 equatorial head and even the heaviest rated payloads with ease.
Optical tube mounting method: The mount head accepts industry-standard Vixen-style dovetails.
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.
Mount | German Equatorial Mount |
Payload * | 28 lbs (12.7kg), exclude counterweight |
Mount weight | 10 lbs (4.5kg) |
Payload/Mount weight | 2.80 |
Structure Material | All metal, Casting + CNC machined |
Exterior Finish | Powder coating |
Periodic error (PE) ** | <±10 arcsec |
PEC | Yes, Permanent PEC |
Worm period | 600 sec |
Right Ascension worm wheel | Φ88mm, 144 teeth aluminum |
Declination worm wheel | Φ88mm, 144 teeth aluminum |
Right Ascension axis shaft | Φ35mm steel |
Declination axis shaft | Φ35mm steel |
Right Ascension bearing | Φ55mm ball bearing |
Declination bearing | Φ55mm ball bearing |
Worm gears | Φ15.2mm, Brass |
Motor drive | 1.8º stepper motor, 128X microdivision |
Resolution | 0.17 arc seconds |
Transmission | Synchronous belt |
Latitude adjustment range | 10º ~ 70º |
Azimuth adjustment range | ± 6º |
Polar Scope | iPolar Electronic polar scope |
Level indicator | Level bubble |
Hand Controller | Go2Nova® 8409 with ~212,000 objects database |
Tracking | Automatic |
Slew speed | 1×,2×,8×,16×,64×,128×,256×,512×,MAX(6º/sec) |
Power consumption | 0.6A(Tracking), 0.9A(GOTO) |
Power requirement | 12V DC, 5A |
AC adapter | 100V ~ 240V (included) |
Power-down memory | Yes |
Wi-Fi | Built-in |
Communication port | Yes (Wi-Fi and USB) |
Autoguide port | Yes (ST-4 compatible) |
Firmware upgrade | Yes |
PC computer control | Yes (ASCOM) |
Counterweight shaft | Φ20X200mm (M16), Stainless Steel |
Shaft extension | Φ20X120mm (M16), Stainless Steel |
Counterweight | 10 lbs (4.5kg) |
Tripod | 1.75" Stainless Steel (5kg) |
Dovetail saddle | 3.8" Vixen-style, center adjustable |
Carrying case | Optional |
GPS | Optional external 32-channel GPS |
Autoguiding | Optional external iGuider 1 |
Operation temperature | -10ºC ~ 40ºC |
Warranty | Two year limited |
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