The iOptron HEM27 with iPolar takes one of the lightest serious imaging mounts in its class and solves another part of portable setup at the same time: polar alignment.
The mount head weighs just 8.15 lb (3.7 kg) with the saddle installed, yet iOptron rates it to carry 29.7 lb (13.5 kg) without a counterweight. Built into the right-ascension axis is iOptron's iPolar electronic polar scope, which uses a camera and plate-solving software to show you exactly how to adjust the mount toward the celestial pole.
That combination makes the HEM27 particularly attractive for travel and backyard astrophotography. You carry far less mount than a traditional equatorial system with comparable useful payload, and you do not have to kneel behind a conventional polar-scope reticle or rely on Polaris itself being visible.
The HEM27 uses a hybrid drive system: strain-wave gearing on right ascension for high torque in a compact package, and a backlash-free worm-and-belt drive on declination. The result is a mount designed around portability while still providing the guiding, GoTo, computer control, and cable management expected from a modern imaging system.
Features
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Built-in iPolar electronic polar scope. The camera and iPolar software plate solve the polar-region star field and provide on-screen guidance for adjusting the mount's altitude and azimuth.
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Approximately 30-arcsecond polar-alignment precision. iOptron specifies iPolar alignment accuracy at approximately 30 arcseconds.
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Polaris does not have to be visible. iPolar solves the surrounding star field rather than requiring you to place Polaris on a reticle. The same system works in the Southern Hemisphere without requiring Sigma Octantis itself to be visible.
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29.7 lb counterweight-free payload. Carry up to 13.5 kg without a conventional counterweight shaft and stack of weights.
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Only 8.15 lb with the saddle installed. The payload-to-mount-weight ratio is approximately 3.65:1.
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Up to 44 lb with a counterweight. Add the optional shaft and counterweight when a heavier or more demanding telescope configuration calls for additional capacity.
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Hybrid drive system. The RA axis uses a strain-wave drive while DEC uses iOptron's backlash-free worm-and-belt system.
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360-second RA gear period. The standard HEM27 does not include the high-precision RA encoder of the HEM27EC, so long-exposure imagers should plan on guiding when their image scale requires it.
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Go2Nova 8409 hand controller included. Standalone GoTo control with an approximately 212,000-object database and nine slew speeds up to 6° per second.
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Wi-Fi through the hand controller. The 8409 provides wireless connectivity for compatible applications such as iOptron Commander Lite and SkySafari.
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Integrated ST-4 autoguider port. Traditional autoguiding is supported in addition to software-based pulse guiding.
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Power and USB pass-through at the saddle. Two 12V outputs with a combined 4A maximum and a USB 2.0 connection help keep camera and accessory wiring close to the telescope.
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Electronic friction brake. Designed to stop the mount safely during a planned or unexpected interruption in power.
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Automatic zero-position search. Built-in sensing allows the mount to locate its reference position electronically.
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Vixen/Losmandy-D convertible saddle. The same saddle accepts either standard, although changing between them requires reconfiguring the saddle hardware.
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Soft carrying case included. Appropriate for a mount designed around portability.
iPolar Is the Difference
The standard HEM27 has no polar scope at all. The H272A adds iPolar directly to the mount.
Instead of looking through a small optical reticle and placing Polaris at a calculated position, iPolar photographs the sky around the celestial pole and plate solves the field. The software then shows the relationship between the mount's RA axis and the true celestial pole.
You make the altitude and azimuth adjustments while watching the result on screen. Bring the mount-axis indicator onto the pole indicator and the alignment is complete.
Polaris itself does not need to be visible. That can be genuinely useful in a backyard where a tree branch or roofline blocks the star even though enough of the surrounding polar-region sky remains open for the software to identify the field.
The same principle applies in the Southern Hemisphere. You do not have to identify Sigma Octantis or change to a different reticle pattern.
30-Arcsecond Polar Alignment
iOptron specifies iPolar alignment precision at approximately 30 arcseconds.
That level of accuracy is far beyond what is needed simply for GoTo pointing. For astrophotography, however, good polar alignment reduces declination drift, helps limit field rotation, and gives the guider less unnecessary work to do over a long imaging session.
It is important to separate polar alignment from tracking performance. iPolar accurately aligns the mount's RA axis with the celestial pole; it does not remove periodic error from the drive. The standard HEM27 is still a non-encoder strain-wave mount, so demanding long-exposure imaging should normally be guided.
Why iOptron Calls It a Hybrid
The HEM27 is not a conventional German equatorial mount and it is not a dual-strain-wave mount either.
Right ascension uses a strain-wave drive. That is the axis doing the continuous tracking work, and the compact, high-torque design is what lets the mount carry a substantial payload without requiring an equally substantial counterweight on the other side.
Declination uses a different solution: iOptron's backlash-free worm-and-belt system. The DEC axis includes a gear switch so it can be released for balancing.
No RA balancing is required. That is one of the biggest practical differences between setting up the HEM27 and setting up a traditional German equatorial mount.
29.7 Pounds Without a Counterweight
The published payload is 29.7 lb, but telescope geometry matters along with scale weight.
iOptron bases the rating on the payload's center of gravity being approximately 200mm from the RA rotation axis, or an OTA roughly 220mm in diameter. A compact 25-pound imaging system and a long 25-pound refractor do not place the same load on the mount.
That makes the HEM27 particularly natural under compact refractors and astrographs where the mass remains relatively close to the RA axis. Longer tubes, large rear-mounted imaging trains, and wind-sensitive systems deserve more margin below the published payload rating.
If the system needs more capacity, the optional counterweight shaft and weight raise the published rating to 44 lb.
Built to Be Guided
The standard HEM27 does not include the high-precision RA encoder found in the HEM27EC.
For long-exposure deep-sky imaging, guiding is the sensible approach. The mount provides an ST-4 autoguider port and also supports software-based guiding through compatible computer-control systems.
Strain-wave mounts can behave differently from conventional worm-drive mounts because their tracking rate can change relatively quickly through portions of the gear cycle. That often makes relatively frequent guide corrections useful, but there is no single exposure time or aggressiveness setting that belongs on every HEM27.
Seeing, guide-camera sensitivity, focal length, image scale, wind, and tripod rigidity all affect the result. Tune the guider from the actual stars in your exposures rather than trying to reproduce somebody else's RMS number.
Clean Cabling at the Telescope
A portable mount loses some of its appeal if every setup involves rebuilding a web of cables.
The HEM27 routes its main wiring internally and provides two 12V outputs plus USB 2.0 pass-through near the saddle. Cameras and accessories can therefore use short cables at the telescope instead of having every connection hang across the moving axes.
The two 12V outputs provide up to 4A combined. That does not replace a full power-management system for every imaging rig, but it can substantially simplify a typical portable setup.
Go2Nova Control and Wi-Fi
The included Go2Nova 8409 hand controller gives the HEM27 standalone GoTo control with an approximately 212,000-object database and nine slew speeds up to 6° per second.
Wi-Fi is provided through the hand controller, so keep the handset connected when you want to operate the mount wirelessly through iOptron Commander Lite, SkySafari, or another compatible application.
Computer control is also available through USB. Windows users can work through iOptron Commander and ASCOM, while third-party INDI support provides additional options on macOS, Linux, and Raspberry Pi systems.
From the Cloudy Nights Community
HEM27 owners on Cloudy Nights repeatedly come back to the same benefit: the low mount weight makes the system much easier to actually use.
One longtime owner who also uses an HEQ5 described the HEM27's altitude and azimuth locking bolts as an annoyance, but considered them a small price to pay for a mount he could simply pick up and carry outside instead of keeping on wheeled bars in the garage.
That complaint is worth knowing before the first night out. The altitude and azimuth locks use socket-head hardware rather than large hand knobs, so keeping the correct hex tool with the mount makes setup much easier.
Owners also point out that the Vixen/Losmandy saddle is convertible rather than instantly dual-width. Switching between the two standards requires moving and flipping parts of the saddle, so it is a job best done indoors before heading to the field.
iPolar itself has a strong following among iOptron users. Experienced owners report that it is quick and repeatable once properly calibrated, and some verify the finished alignment afterward with PHD2 Guiding Assistant. That is useful context: iPolar is primarily about making a good polar alignment fast and repeatable, not about replacing guiding or solving every tracking issue downstream.
A Few Setup Details Worth Knowing
The HEM27 has two normal latitude ranges: 15–41° and 39–65°. Switching between them requires relocating hardware inside the latitude adjustment assembly, so it is something to do at home rather than discovering after dark at a distant observing site.
The saddle also ships configured for Vixen dovetails. If your telescope uses a Losmandy-D plate, convert the saddle before the first observing session and leave it set for the dovetail standard you normally use.
With a longer refractor or deep imaging train, a MiniPier can also be useful for keeping the camera and focuser clear of the tripod legs near the meridian and zenith.
What's Included
- iOptron HEM27 hybrid strain-wave equatorial mount head
- Factory-installed iPolar electronic polar scope
- Vixen/Losmandy-D convertible dovetail saddle
- Go2Nova 8409 hand controller
- 6P6C coiled hand-controller cable
- 12V/5A AC adapter for indoor use
- USB cable for mount control
- Mini-USB cable for iPolar
- Soft EVA carrying case
Not included: tripod, counterweight shaft, or counterweight.
Frequently Asked Questions
What is the difference between this HEM27 and the standard HEM27?
The H272A includes iOptron's iPolar electronic polar scope built into the mount. The H272 uses the same basic hybrid drive and has the same payload rating but does not include a polar scope.
Do I need to see Polaris to use iPolar?
No. iPolar plate solves the surrounding polar-region star field, so Polaris itself does not need to be visible. Enough surrounding sky still needs to be visible for the camera and software to identify the field.
How accurately can iPolar align the mount?
iOptron specifies maximum polar-alignment precision of approximately 30 arcseconds.
Does iPolar require a computer?
Yes. iOptron's official iPolar software runs on a Windows computer. The iPolar camera connects through its Mini-USB port during polar alignment. Once alignment is complete, the iPolar computer connection is no longer required simply for the mount to track.
How much can the HEM27 carry without a counterweight?
iOptron rates it for 29.7 lb (13.5 kg) without a counterweight. The rating assumes the payload center of gravity is approximately 200mm from the RA axis, so telescope geometry matters along with total weight.
How much can it carry with a counterweight?
With the optional counterweight shaft and weight, iOptron raises the published payload rating to 44 lb (20 kg), subject to the same payload-geometry considerations.
Should I guide the standard HEM27?
For typical long-exposure deep-sky imaging, yes. This HEM27 does not include the high-precision RA encoder of the HEM27EC. The mount supports both ST-4 and software-based guiding.
Does iPolar replace guiding?
No. iPolar handles polar alignment. Guiding corrects tracking errors while the mount is operating. They solve different problems.
Does the mount work with ASIAIR?
HEM27 owners use the mount successfully with ASIAIR systems, although connection methods can vary with ASIAIR and mount firmware revisions. The mount's Wi-Fi is provided through the 8409 hand controller.
Does it work with NINA?
Yes. On Windows, the HEM27 can be controlled through iOptron Commander and ASCOM, allowing compatible applications such as NINA and PHD2 to communicate with the mount.
Is the saddle really Vixen and Losmandy compatible?
Yes, but it is convertible rather than instantly dual-width. The saddle ships configured for Vixen plates. Changing it to Losmandy-D requires repositioning and flipping parts of the saddle assembly.
What tripod fits it?
The HEM27 is compatible with iOptron's LiteRoc tripod for the CEM26/HEM27/GEM28/HAE29 family as well as compatible carbon-fiber tripod options. A matching MiniPier is useful when additional telescope-to-tripod clearance is needed.
Final Thoughts
The HEM27 with iPolar is for the imager who wants to remove two common excuses for leaving the telescope inside: a heavy mount and an awkward polar-alignment routine.
The mount head weighs just 8.15 pounds, carries 29.7 pounds without a counterweight, and fits into a soft case small enough to travel easily. The built-in iPolar camera replaces the traditional polar-scope reticle with plate solving and on-screen adjustment guidance, without requiring Polaris itself to be visible.
Underneath that convenience is still a capable imaging mount: strain-wave RA, backlash-free worm-and-belt DEC, Go2Nova control, Wi-Fi, guiding support, saddle-mounted power and USB, an electronic brake, and automatic zero-position search.
Plan to guide it for serious long-exposure work, keep the telescope geometry sensible, and the HEM27 with iPolar gives you a portable imaging system that is quick enough to set up that a clear weeknight can actually become an imaging night.
