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iOptron HEM27 Mount
iOptron HEM27 Mount - HEM27EC Mount
iOptron HEM27 Mount - HEM27EC Mount

iOptron HEM27 Mount

by iOptron
SKU IOP-H272
CA$2,797.00 - CA$4,983.00
CA$2,855.00
CA$2,797.00 - CA$4,983.00
CA$2,855.00
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  • Hybrid Drive: StrainWave 17 RA gear (480:1) with backlash-free worm/belt DEC
  • 29.74 lbs (13.5 kg) payload without counterweights, 44 lbs (20 kg) with optional counterweight
  • 8.15 lbs (3.7 kg) mount head for a 3.65 payload-to-weight ratio
  • Go2Nova® 8409 controller with ~212,000 objects and built-in Wi-Fi
  • High-precision RA encoder with Realtime PEC (EC versions)
  • Available with internal iPolar electronic polar scope (~30 arcsec precision)
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • iOptron HEM27 Mount

    The iOptron HEM27 Mount uses a StrainWave 17 gear on its right ascension axis to carry a 29.74 lbs payload without a counterweight, all from a mount head that weighs just 8.15 lbs. That is a 3.65 payload-to-weight ratio. The mount has a Go2Nova® 8409 hand controller with a ~212,000-object database and a 6º/sec maximum slew speed. It has built-in Wi-Fi and an electronic friction brake, and is offered in standard and EC versions (the EC adds a high-precision RA encoder for Realtime PEC), each with or without the internal iPolar electronic polar scope.

    A Hybrid StrainWave 17 RA and Worm/Belt DEC System

    The core of the HEM27 is its hybrid drive system, which combines a StrainWave 17 gear on the right ascension axis (480:1 reduction) with a backlash-free worm/belt system for declination.

    The drive is a stepper motor, and the period is 360 seconds.

    3.65 Payload-to-Weight Ratio: 29.74 lbs from an 8.15 lb Head

    Weighing only 8.15 lbs (3.7 kg) with its dual Vixen & Losmandy saddle, the HEM27 mount head can carry up to 29.74 lbs (13.5 kg) of equipment without a counterweight. The mount head weighs 7.49 lbs (3.4 kg) without the saddle, and the payload-to-mount weight ratio is 3.65.

    With the optional counterweight shaft (stainless steel, Φ20 x 200 mm, M16 thread) and the optional 10 lbs (4.5 kg) counterweight, the rated payload is 44 lbs (20 kg).

    Tracking Precision: 360s Period and Realtime PEC on EC Models

    The HEM27EC version integrates a high-precision encoder directly into the RA drive axis. It enables Realtime PEC.

    PEC is available only on the EC versions (Realtime PEC), and no periodic error figure is published for the HEM27, so none is stated here.

    GoToNova® Controller: 212,000 Objects and 6°/sec Slewing

    The included Go2Nova® 8409 hand controller has a database of approximately 212,000 objects, and tracking is automatic. The mount can slew to targets at a maximum speed of 6º/sec.

    The control system is GOTONOVA/Commander, and the firmware is upgradeable. The hand controller operates from -10ºC to 40ºC; the mount from -20ºC to 40ºC.

    Integrated Connectivity: Wi-Fi, USB, ST-4, and 2 x 12V DC Outputs

    Every HEM27 version has built-in Wi-Fi, and the control system is GOTONOVA/Commander. A USB port provides a wired connection, and there is an ST-4 compatible autoguide port.

    Cable management provides two 12V outputs (4A max.) and one USB 2.0 port, and the cables do not move or wrap.

    Polar Alignment with iPolar: ~30 Arcsecond Precision via Software

    The HEM27 has no optical polar scope. The "w/ iPolar" versions include iOptron's internal iPolar electronic polar scope, listed at about 30 arcsec precision.

    The mount's base provides a latitude adjustment range of 15º to 65º and an azimuth adjustment range of ± 5º for fine-tuning the alignment.

    Choosing Your HEM27: A Guide to the EC and iPolar Versions

    All HEM27 models share the same core mechanics, 29.74 lbs counterweight-free payload, Go2Nova® controller, and built-in Wi-Fi. The differences are the RA encoder, the iPolar and the latitude range.

    • HEM27 Mount: The base model, without a polar scope.
    • HEM27 Mount w/ iPolar: Adds the internal iPolar electronic polar scope.
    • HEM27EC Mount: Adds the high-precision RA encoder for Realtime PEC, without a polar scope.
    • HEM27EC Mount w/ iPolar: Combines the RA encoder for Realtime PEC with the internal iPolar.
    • HEM27 Mount Low-Latitude (0-22°): A version of the base HEM27 with a 0° to 22° latitude range. It is not in the current site copy; low-latitude HEM27 mounts are a special order.

    Note: The exact mount head model (standard or EC) and inclusion of the iPolar electronic polar scope depends on the version selected.

  • What are the main differences between the iOptron HEM27 versions?

    All versions share the same StrainWave hybrid drive, 29.74 lbs (13.5 kg) payload capacity without counterweights, and Go2Nova® 8409 controller. The key differences are:

    • HEM27EC versions include a high-precision RA encoder that enables Realtime Periodic Error Correction (PEC).
    • "w/ iPolar" versions include the internal iPolar electronic polar scope (about 30 arcsec precision).
    • The Low-Latitude version (special order) covers latitudes from 0º to 22º, while standard versions support 15º to 65º.

    Does the iOptron HEM27 mount require counterweights?

    Not up to its counterweight-free rating. The iOptron HEM27 carries a payload of up to 29.74 lbs (13.5 kg) without any counterweights. If your telescope and imaging gear exceed this weight, you can add the optional counterweight shaft and a 10 lbs counterweight to increase the total capacity to 44 lbs (20 kg).

    What is a StrainWave gear and why does the iOptron HEM27 use it?

    A strain wave (harmonic) gear uses a flexible gear element to reach a high reduction ratio in a compact unit; the HEM27 uses a StrainWave 17 gear with a 480:1 ratio on its RA axis. No backlash or accuracy figures are stated for it, and the DEC axis uses a backlash-free worm/belt system.

    How do I polar align the iOptron HEM27 for astrophotography?

    The HEM27 mount does not have a traditional optical polar scope. Versions with the integrated iPolar electronic polar scope use it for polar alignment (listed at about 30 arcsec precision). Versions without it need another polar alignment method; none is specified for the HEM27.

    Can I control the iOptron HEM27 mount from a computer or smartphone?

    Yes. Every HEM27 version has built-in Wi-Fi, and the control system is GOTONOVA/Commander. A USB port is also available for a wired connection.

    What does the HEM27's electronic friction brake do?

    The power-off brake is an electronic friction brake, so the axes are held when the mount is not powered.

    What power supply do I need for the iOptron HEM27?

    The mount requires a DC 12V, 5A power source with a 5.5mm/2.5mm plug. It consumes about 0.5A while tracking and 1A during GoTo. A 100V ~ 240V AC adapter is included, for indoor use only.

    Can I use a Losmandy-style dovetail plate with the HEM27?

    Yes. The iOptron HEM27 comes standard with a Vixen & Losmandy dual dovetail saddle. It accepts both Vixen-style and Losmandy-style dovetail bars.

  • Mount Type Hybrid Equatorial Mount
    RA Gear System StrainWave 17
    DEC Gear System Backlash-free worm/belt system
    RA Reduction Ratio 480:1
    Payload (No Counterweight) 29.74 lbs (13.5 kg)
    Payload (With Counterweight) 44 lbs (20 kg)
    Mount Weight 7.49 lbs (3.4 kg) w/o saddle, 8.15 lbs (3.7 kg) with saddle
    Payload to Mount Weight Ratio 3.65
    Drive Motor Stepper motor
    Native Period 360 seconds
    High Precision Encoder Yes, RA axis (EC versions); none (non-EC versions)
    Periodic Error Correction (PEC) Realtime PEC (EC versions)
    Structure Material All metal, CNC machined
    Exterior Finish Anodized black
    Dovetail Saddle Vixen & Losmandy dual saddle
    Latitude Adjustment Range 15º ~ 65º (all other versions); 0º ~ 22º (Low-Latitude version)
    Azimuth Adjustment Range ± 5º
    Control System GoToNova® / Commander
    Hand Controller Go2Nova® 8409 with ~212,000 objects database
    Maximum Slew Speed 6º/sec
    Power Requirement DC 12V, 5A (5.5mm/2.5mm plug)
    Power Consumption 0.5A (Tracking), 1A (GoTo)
    Power Off Brake Electronic friction brake
    Built-in Wi-Fi Yes
    Communication Ports Wi-Fi and USB
    Autoguide Port Yes (ST-4 compatible)
    Cable Management 2 x 12V DC Out (4A max), 1 x USB 2.0 Port
    Optical Polar Scope No
    Electronic Polar Scope Internal iPolar, ~30 arcsec precision (iPolar versions)
    Level Indicator Level bubble
    Firmware Upgradeable Yes
    Tripod Optional
    Counterweight & Shaft Optional
    Operating Temperature -20ºC ~ 40ºC
    Counterweight 10 lbs (4.5 kg) (optional)

    • HEM27 Mount Head (non-EC versions)

      × 1

    • HEM27EC Mount Head with RA Encoder (EC versions)

      × 1

    • Vixen & Losmandy Dual Dovetail Saddle

      × 1

    • Go2Nova® 8409 Hand Controller

      × 1

    • Internal iPolar Electronic Polar Scope (iPolar versions)

      × 1

    • 100V ~ 240V AC adapter

      × 1

  • iOptron 2-Year Limited Warranty