ZWO EAF knockoff Gemini EAF

The Gemini Electronic Auto Focuser, often abbreviated as Gemini EAF, is a cost-effective motorized focuser designed for astronomical telescopes. Aimed at astrophotographers seeking precision without the premium price tag, it delivers key automation features at a fraction of the cost of brand-name focusers. With a compact motor housing, universal bracket, and software compatibility across popular platforms, the Gemini EAF makes auto focusing accessible for beginners and budget-conscious enthusiasts alike. While it does not integrate with ZWO’s ASIAir control system due to driver limitations, it otherwise offers broad support for telescope control software through ASCOM and INDI.

ZWO EAF knockoff Gemini EAF: Worth it or waste of money?

Manufactured in China and sold through retailers like LittleLightStore on AliExpress, the Gemini EAF is currently listed at $64.05 USD before shipping for the base model. A second version, priced at $71.17, includes a basic infrared remote controller for manual adjustments. This remote may appeal to visual observers or those preferring occasional offline operation, though most astrophotographers will likely use the USB connection and software interface for full automation. Despite its low price, the Gemini EAF includes essential components needed for mounting and setup across a wide range of telescope types.

Constructed with a CNC-machined mounting bracket and featuring three elastic couplers for compatibility with various shaft sizes, the device can be adapted to common focusers on telescopes like the Sky-Watcher, Celestron 6SE and 8SE, and similar OTA designs. The system runs on a 5V USB power supply and connects to control software through a USB 2.0 data line. While users should not expect the refined polish or fit of high-end focusers, early impressions from hobbyists suggest that functionality remains solid, with the core task of consistent, stepper-driven focusing handled effectively.

One caveat to note is the method of software driver delivery. The ASCOM driver is not available from an official manufacturer's website but instead via a QR code printed on the packaging, which links to a Microsoft OneDrive folder. While this may raise eyebrows from users accustomed to more professional distribution channels, the driver itself installs correctly and enables control through supported applications like NINA, KStars, and other major imaging platforms. Once operational, the device offers reliable movement and solid performance at a price that lowers the barrier to entry for many aspiring deep sky imagers.

The Gemini Electronic Auto Focuser (EAF) specifications

• USB 5V power input
• ASCOM and INDI software support
• Windows control software included
• Three-gear precision control motor
• Maximum handle control range: 5 meters
• Handle control data recording function
• 3840 motor steps per rotation
• Maximum travel range: 2 million steps
• Software compatibility: NINA, KStars, MDL, etc.
• Telescope compatibility: Sky-Watcher, Sky Rover, Celestron C8, 6SE, 8SE, CYCK, 2047, and others
• Not compatible with ZWO ASIAir control, though it can be powered via the ZWO box for manual remote control use
   

Included in the package

• Focusing body ×1
• CNC mounting bracket ×1
• USB 2.0 data cable (1.5 meters) ×1
• Elastic linkers ×3 (sizes: 5-4, 5-5, 5-6)
• M4 screws ×4
• M5 screws ×2
• Temperature probe ×1
   

The value proposition of the Gemini EAF becomes especially clear when considering what’s included in the box for such a low cost. The essentials are all there, bracket, couplers, screws, cable, and a working temperature sensor, which gives users everything needed for installation on a wide variety of telescope setups. Whether the user is outfitting a Newtonian reflector or a Schmidt-Cassegrain, the range of mechanical adaptors included ensures flexibility in deployment. Although some of the materials may lack the refined finish of premium focusers, nothing critical is omitted.

In practice, the Gemini EAF behaves much like its more expensive competitors once properly installed and configured. Its 3840-step motor resolution offers sufficient precision for fine focusing adjustments, and software like NINA can easily leverage those small increments to perform automated focus routines. The temperature probe adds an additional layer of utility for users needing to compensate for ambient thermal drift during long exposures, a crucial factor in maintaining image sharpness across changing night conditions.

Overall, the Gemini EAF delivers core auto-focus functionality without frills. It’s clearly manufactured with cost-efficiency in mind, but not at the expense of basic performance. For those willing to navigate around a few setup quirks, such as manual driver downloads or slightly rough mechanical finishes, the Gemini EAF represents an excellent entry point into automated focusing. Its affordability opens up possibilities for beginners to experiment with advanced imaging techniques that would otherwise require a far larger investment.

Download the driver

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What AstroOnBudget had to say about the Gemini Electronic Auto Focuser (EAF)

The Gemini Electronic Auto Focuser, or Gemini EAF, stands out as a compelling choice for astrophotographers seeking a high-quality, budget-friendly alternative to the more expensive electronic focusing systems on the market. Presented by AstroOnBudget, this review offers a thorough hands-on assessment of the Gemini EAF, highlighting both its practical benefits and a few shortcomings. The creator’s main goal was to evaluate whether this affordable focuser can deliver the kind of precision and reliability that deep space imaging demands, and the result is a compelling argument in its favor for most hobbyists and amateur astrophotographers.

From the outset, the video stresses the crucial role of precise focus in astrophotography. Achieving pinpoint focus is fundamental when capturing celestial objects, especially for long-exposure deep space imaging. Manual focusing can be frustrating and imprecise, particularly as temperature changes cause shifts in focus throughout an imaging session. This is where motorized electronic focusers come into play. They allow for precise, repeatable adjustments and integrate seamlessly with software automation tools like NINA or KStars. The Gemini EAF fits this role admirably, doing so at a fraction of the cost of high-end alternatives like the ZWO EAF.

AstroOnBudget reveals that the Gemini EAF was sourced through AliExpress for approximately 70 US dollars. Despite its low price point, the unit arrived well-packaged in a simple brown box and included all the necessary parts to fit most commonly used telescopes. The only notable omission was a screwdriver for the grub screws, which, while not a major issue, could be inconvenient for users expecting a fully self-contained package. Nevertheless, the inclusion of mounting brackets and screws for different telescope models demonstrates thoughtful design, especially at this price.

Build quality was another focal point in the review. The Gemini EAF appears to be robust and durable, though the reviewer acknowledges that the bracket from ZWO might be slightly higher in quality. Still, AstroOnBudget expresses no real concerns about this difference. The core performance of the Gemini EAF, the ability to accurately and consistently control the focus, remains uncompromised. The body feels sturdy, and more importantly, it performs reliably during astrophotography sessions, which is ultimately the benchmark that matters.

In terms of connectivity and operation, the Gemini EAF uses a single USB cable that doubles as its power supply. It operates at 5 volts and offers broad compatibility with software platforms via ASCOM and INDI drivers. AstroOnBudget has primarily used the device with NINA, a popular astrophotography planning and automation tool, and reports seamless integration. The focuser never missed a beat, even during extended imaging sessions, which underscores its reliability when paired with modern astrophotography software.

A more technical breakdown of the Gemini EAF’s capabilities reveals some impressive specifications for such a low-cost device. It features a three-gear precision control mechanism, which contributes to its fine adjustment capabilities. With 3840 steps per revolution and a maximum movement range of up to 2 million steps, the device offers granular control over the focus position, essential for dialing in that perfect point of sharpness in deep space targets. Its control range extends up to five meters, accommodating a wide variety of telescope setups and mount configurations.

The unit also includes a temperature sensor, which plays a critical role in compensating for thermal shifts. As ambient temperatures drop during the night, materials in the telescope contract slightly, affecting focus. The ability to account for and adjust to these shifts automatically is a major asset. AstroOnBudget found the temperature readings to be reasonably accurate, adding yet another layer of usefulness to the product.

However, the review is not without a few criticisms. One of the more unusual aspects is how the driver software is distributed. Instead of being available from a centralized and professional-looking download site, the drivers are shared via a private Google Drive link. While the drivers work as intended, this method of distribution may raise eyebrows for users who are more cautious about software provenance. It doesn't affect the performance of the device, but it could be improved with a more transparent and official hosting solution to build confidence among first-time users.

Another minor downside is the presence of slight backlash in the focusing mechanism. Backlash, essentially a small lag in movement when the direction of focus is reversed, is a common issue with many motorized focusers. While not ideal, AstroOnBudget notes that the backlash is within acceptable levels and comparable to what’s found in significantly more expensive models. It’s a manageable issue and doesn’t significantly detract from the overall user experience, particularly if software compensation is enabled.

Taken together, these elements contribute to a favorable overall impression of the Gemini EAF. AstroOnBudget emphasizes that the focuser performs on par with the more premium ZWO EAF in terms of basic functionality. While it may lack some polish or branding sophistication, it delivers where it counts, offering reliable, precise focusing control for a fraction of the cost. For astrophotographers on a budget, especially those just getting started or looking to automate their workflow without heavy investment, this device hits a sweet spot.

The review closes with a reaffirmation of value. At around 70 dollars, the Gemini EAF is significantly cheaper than many of its competitors but holds its own in practical performance. Its strong compatibility with major astrophotography platforms, solid build quality, and sufficient precision make it a highly attractive entry point into the world of automated focusing. AstroOnBudget encourages viewers with any additional questions to leave comments, promising to respond and provide guidance where needed.

In sum, the Gemini Electronic Auto Focuser stands out as a thoughtfully designed, accessible tool for anyone looking to improve their astrophotography without breaking the bank. It offers the key benefits of electronic focusing, automation, precision, and stability, at a cost that is hard to ignore. While a few areas could be improved, such as packaging completeness and software distribution, these issues are minor when weighed against the focuser’s performance and affordability. AstroOnBudget’s review offers a clear endorsement for the Gemini EAF as the ultimate budget-friendly focuser for deep space imaging.

Gemini EAF: The Ultimate Budget Electronic Focuser for Astrophotography!

What Cuiv the Lazy Geek had to say about the Gemini Electronic Auto Focuser (EAF)

Cuiv the Lazy Geek’s review of the Gemini Electronic Auto Focuser (EAF) presents a critical yet ultimately positive look at what is quickly becoming one of the most popular budget-friendly electronic focusers in the astrophotography community. Priced at a mere $70 USD, this focuser costs less than half of its closest major competitor, the ZWO EAF, and yet aims to provide the same core functionality. Cuiv, known for his honest and hands-on gear assessments, approaches this device with a mix of curiosity, skepticism, and technical precision. By the end of his comprehensive test, the Gemini EAF proves itself to be a viable and surprisingly capable option for astrophotographers looking to automate their focusing process without breaking the bank.

The initial presentation of the Gemini EAF doesn’t exactly inspire confidence. The device arrives in a generic box labeled differently than the product itself, with the box reading “Gemini Electronic Automatic Focuser” and the device labeled “Automatic Star Focuser Pro.” Cuiv jokingly notes the inconsistency, suggesting that the manufacturer hasn’t quite finalized its branding. Still, he pushes forward to see if the functionality will redeem the lack of polish. As he explores the product, he finds it supports both ASCOM and INDI, two of the most widely used standards for telescope accessory control. His first test is with StellarMate Pro using INDI, and the device connects immediately and works without issue. This initial success sets a positive tone, especially for users who prefer open-source platforms.

However, issues arise when attempting to install the ASCOM driver. The QR code on the packaging leads to a Microsoft OneDrive link, which fails to deliver the required file. A secondary link to a private Facebook group is also problematic, requiring approval to join. Eventually, Cuiv finds a working driver copy from another site, but the experience is far from smooth. He recommends that the manufacturer establish a reliable, official download portal for drivers, something essential for maintaining user trust and professionalism. Still, Cuiv’s persistence pays off, and he gets the software working on his Windows system.

Opening the box reveals a complete, albeit slightly disorganized, set of accessories. These include a working temperature sensor, a USB cable with an angled adapter, and a metal bracket that appears to be a direct clone of the ZWO EAF bracket. The device also comes with three couplers instead of the four ZWO includes, offering different shaft diameter options for compatibility with various telescope focusers. Some minor complaints follow, such as screws and washers being loosely tossed in the box instead of packed properly, and an empty plastic bag included for no apparent reason. Cuiv shrugs these off as part of the budget experience, annoying but ultimately inconsequential if the product delivers solid performance.

On physical inspection, the focuser appears slightly larger than the ZWO unit, with a noticeably bulkier profile. However, it is significantly lighter, weighing in at 191 grams compared to the ZWO’s 277 grams. This weight difference makes it feel a bit “cheap” in hand, according to Cuiv, but he emphasizes that performance is what truly matters. One odd design choice he notes is that the shaft of the focuser has two flat surfaces for gripping instead of one. While this would imply a matched coupler design with dual screws aligned to these flats, the included couplers instead have screws offset at 120 degrees, defeating the supposed benefit. Again, Cuiv is unfazed, as long as the system holds together during operation.

He installs the Gemini EAF onto his carbon Newtonian telescope with minimal difficulty. The process mirrors that of the ZWO EAF, taking about five minutes with a few screws and hex wrenches. Users should note that unlike ZWO, which typically includes tools, the Gemini requires you to bring your own. Cuiv confirms the screws use a 3 mm hex key and suggests this isn’t a problem for seasoned users who already have a set of tools.

Before getting into the full field test, Cuiv does a manual visual inspection of the focuser’s backlash by observing the movement of the shaft. He estimates it at about 10 to 15 steps, a relatively small amount. However, when later tested under real astrophotography conditions, the effective backlash measured closer to 30 steps. This discrepancy, he explains, is likely due to torque differences and play in the coupler when the focuser is installed on an actual telescope. Importantly, he demonstrates how to mitigate this by configuring backlash compensation in the popular software NINA. By enabling overshoot backlash correction and setting it to a value higher than the observed backlash, he uses 100 steps just to be safe, he’s able to get clean, repeatable autofocus results.

The temperature sensor also performs reasonably well in Cuiv’s indoor tests. When compared to a room thermometer, the readings from the Gemini EAF were within a few degrees Celsius. He also observes the temperature rising quickly when held in hand, indicating a working and responsive sensor. While others have reported issues with the sensor not functioning, Cuiv’s unit seems fine. He also mentions a heating feature that could theoretically warm the focuser in cold conditions using its own electronics, though he hasn’t tested it due to warm summer weather.

During actual nighttime imaging sessions, the Gemini EAF continues to prove its worth. Cuiv tests the device using his Newtonian telescope and confirms that it integrates well with his system. Without backlash correction, the focus was slightly off, leading to visible double diffraction spikes in the star images. However, once backlash correction was implemented in software, the focuser delivered sharp, well-focused images. Cuiv checks the final results with a Bahtinov mask, a tool for assessing focus accuracy, and finds that the focus is indeed spot-on.

In conclusion, Cuiv acknowledges the jankiness of the Gemini EAF. The packaging is sloppy, the software distribution is unprofessional, and the build quality feels cheap. But functionally, the device punches far above its weight. It performs well, integrates easily with both INDI and ASCOM systems, and supports temperature monitoring and backlash compensation. The fact that it doesn’t work with ZWO’s ASIAIR ecosystem is a limitation, but this is not the fault of the Gemini EAF itself, ASIAIR is a closed platform that only supports certain hardware. For users who aren’t locked into that ecosystem, this focuser represents an incredible value.

What really stands out in Cuiv’s review is the careful balance he strikes between criticism and praise. He doesn’t ignore the Gemini EAF’s flaws, but he frames them in the context of its remarkably low price. It may be rough around the edges, but it gets the job done. Cuiv’s final word is one of endorsement. If you’ve been eyeing a motorized focuser but balked at the $200 price tag of more premium options, the Gemini EAF offers a functional, if slightly clunky, alternative for a fraction of the cost. For budget-conscious astrophotographers, that makes it a worthwhile addition to the toolkit.

This BUDGET Electronic Focuser SURPRISED me! Gemini EAF

What Ollies Space had to say about the Gemini Electronic Auto Focuser (EAF)

In a first-look review posted to his YouTube channel, Ollies Space shares his initial impressions of the Gemini Automatic Star Focuser Pro, a budget electronic focuser that he discovered on AliExpress while seeking an alternative to the ZWO EAF. As a user already invested in three ZWO units, Ollie found himself needing a fourth but didn’t want to spend another premium amount. That’s when he came across the Gemini EAF, which, including shipping to Australia, cost him only around 150 AUD, roughly half the price of a standard ZWO EAF. With a mix of cautious optimism and practical curiosity, Ollie walks viewers through what they can expect from this cost-effective option and how it compares to its more expensive counterpart.

Upon unboxing the Gemini focuser, Ollie immediately notes the lack of presentation or branding. The unit comes packed in a plain Styrofoam insert with no outer retail box, no flashy branding, and only basic labeling. While this may seem underwhelming, especially when compared to the more polished packaging from ZWO, it quickly becomes apparent that the manufacturer has cut costs in areas that don’t impact the product’s function. The device itself has a squarish form factor, slightly bulkier than the rectangular ZWO model, and is equipped with the basic expected ports: a temperature sensor port, a USB 2.0 port, and a plug for the included hand controller.

Ollie takes a closer look at the bundled accessories. Along with the focuser unit, users receive a simple hand controller, a temperature probe, three flexible shaft couplers in different sizes, a metal mounting bracket, and a small wireless infrared receiver for the remote. The hand controller appears extremely basic and somewhat plasticky, but it works. Once powered, it can control the motor’s movement in both directions and at different speeds. There are four directional buttons, two for continuous movement and two for smaller step-wise adjustments. A couple of labeled buttons, such as “S” and “M4,” remain a bit of a mystery to Ollie, who speculates on their functions but notes a manual is likely available online.

Despite the no-frills approach, Ollie finds that the remote works surprisingly well, albeit with limited range and the requirement of a direct line of sight to the sensor. For visual astronomy setups, the remote might offer some convenience, but Ollie doubts he will use it often in practice, preferring software control.

In terms of build quality, Ollie gives a fair assessment. The device feels and looks a little cheaper than the ZWO EAF. The couplers, in particular, appear shinier and less refined, lacking the anodized aluminum feel of their ZWO equivalents. However, functionally, everything seems to fit and align properly. He tests mounting the Gemini focuser on an SVBONY telescope where he had previously installed a ZWO EAF, and finds the compatibility almost perfect. The mounting bracket aligns with the existing screw holes, and the spacing of the shaft is spot on. This suggests that the Gemini is more or less a clone of the ZWO design, which may actually work in the buyer’s favor in terms of compatibility with existing rigs.

When Ollie powers up the device and uses the remote to operate it, he observes a slight internal rattle. He speculates this may be the result of backlash or a bit of play in the shaft, which is to be expected from a budget device. However, the focuser responds smoothly to commands, rotating the shaft cleanly in both directions. His early impression is that while it doesn't have the smooth, high-end polish of premium focusers, it does the job, and that’s what counts.

As Ollie puts the Gemini EAF through these initial paces, his tone remains realistic. He doesn't attempt to oversell its virtues, nor does he prematurely dismiss its shortcomings. He admits to being unsure about the long-term durability or the internal engineering quality, and he hasn't yet measured the backlash or tested it under load on a telescope during an actual imaging session. Nevertheless, for the price point, especially considering it includes a temperature probe and wireless remote, the device seems like a remarkable value.

He emphasizes that even if the materials are lower quality or if the unit has minor quirks, the fact that a fully functional electronic focuser is available at this price is worth attention. Ollie reflects on the broader trend in astronomy gear becoming more accessible and affordable, observing how remarkable it is that a device like this can be offered for about 75 USD. He’s cautiously optimistic about the Gemini EAF and expresses excitement about trying it out for solar imaging or future deep sky sessions.

Ultimately, Ollie concludes the video by reiterating that the Gemini EAF “obviously works,” at least on a basic level, and that he looks forward to seeing how it performs in the field. While he doesn't yet have data on its performance with software like NINA or test results from under the stars, his hands-on setup experience is largely positive. The fact that the unit fits ZWO mounting brackets and accessories so well suggests thoughtful design mimicry, if not originality.

For astrophotographers looking to automate their focus without the investment required for a ZWO or similar brand-name solution, Ollie’s first impressions of the Gemini EAF are encouraging. While there are trade-offs in build quality, finish, and packaging, the essential function, the motorized control of a telescope’s focuser, appears to be intact and reliable. He encourages viewers to stay tuned for future videos once he has had a chance to fully test the focuser during an actual imaging session. His pragmatic approach and honest commentary offer a grounded and useful perspective for any amateur astronomer thinking about upgrading their setup on a budget.

In summary, Ollie provides a level-headed and practical first look at the Gemini Automatic Star Focuser Pro. He doesn’t hype the product beyond its real-world presentation but gives it credit where it’s due. For about half the price of a ZWO EAF, the Gemini unit offers a compelling option for those wanting to explore motorized focusing without a heavy investment. While more thorough testing is still pending, the device passes the all-important initial functionality check and shows enough promise to justify a closer look.

First Look - GEMINI Automatic Focuser - Half the cost of ZWO EAF What !!

Buy the Gemini EAF