The RB Focus Gaius-S2 might just be the all-in-one controller that replaces your ASIAIR, Stellarmate, and every other piece of kit astrophotographers have been juggling. Compact yet powerful, this sleek control unit is designed to centralize the management of your entire astrophotography setup—right from your telescope. It merges robust hardware control with the flexibility of a full Windows 11 Pro computer, all housed in a tidy enclosure that mounts directly on your rig.
At its heart is an Intel Celeron N5105 processor running at up to 2.9GHz across four cores, backed by configurable RAM (4GB, 8GB, or 16GB) and storage options (64GB, 128GB, or 256GB). It comes preloaded with essential astrophotography software like N.I.N.A., ASCOM, EQMOD, PHD2, ASTAP, Plate Solve 2, and Stellarium—ready to go from the moment you power it on.
While the Gaius-S2 promises to simplify and streamline astrophotography workflows like never before, it's worth keeping in mind that no system is perfect. There could be limitations or edge cases where it may not fully replace more specialized tools. Still, for many users, this might be the long-awaited single-box solution that brings it all together.
Connectivity is straightforward, with six USB ports, two USB 3.0 and four USB 2.0, suitable for cameras, filter wheels, mounts, and focusers. It includes a 2.5 Gbit LAN port for wired networking and Wi-Fi 6 support with dual antennas for wireless control. There's also a microSD slot and an internal M.2 slot for adding extra storage. It connects via a 12V DC XT30 power input and supports up to 10 amps. For output, it provides five 12V DC ports and two PWM-controlled ports, which are ideal for dew heaters. These outputs can be turned on or off through software, and power data is monitored and displayed.
The included temperature and humidity sensor helps the system manage dew heaters by tracking ambient conditions and calculating the dew point. The software can automatically power the heaters only when needed, helping reduce unnecessary power use and heat.
The unit measures 12 cm x 8.5 cm x 3.2 cm and weighs just 250 grams, so it doesn’t add much bulk to a telescope setup. It includes a small OLED screen that shows live system info such as voltage, amperage, and environmental data, so users can quickly check the system without logging in.
Setup is simple. Once plugged in, users can control the device remotely using Windows Remote Desktop or a phone or tablet through apps like Touch and Stars. The built-in Wi-Fi hotspot allows control from anywhere—even without internet access. If your gear works with ASCOM drivers, it only takes a few minutes to get everything up and running with full control from N.I.N.A.
As of now, the base model of the Gaius-S2 costs €430, which is around $460 USD. The recommended version with 8GB RAM and 128GB storage is €565 (about $600 USD), and the top-end model with 16GB RAM and 256GB storage goes for €665 (roughly $705 USD). Compared to other devices with similar features, especially the Primaluce Lab Eagle 6, the Gaius-S2 delivers similar or better control and performance at a significantly lower price.
The Gaius-S2 is built for users who want a no-nonsense, integrated way to control imaging sessions, manage connected gear, and reduce the clutter of cables and separate devices. It’s not tied to any one brand’s system and supports a wide variety of equipment. With everything pre-installed and ready to go, it’s a practical choice for astrophotographers who are already comfortable working within the Windows ecosystem.
The RB Focus Gaius S2 emerges as a standout among modern control centers for astrophotography, offering a seamless combination of automation, Windows-based flexibility, and affordability. This device was thoroughly reviewed by the creator of the "Lazy Astrophotographer" channel, who is known for his deep dive into gear that reduces manual effort while enhancing imaging efficiency. Over the years, he has tried numerous options, from ZWO’s ASIAir and smart cameras to StellarMate Pro and Touptek’s StellaVita. Despite appreciating those systems, he always finds himself returning to Windows setups, specifically because of their compatibility with software like N.I.N.A., an open-source powerhouse for imaging automation. His prior go-to was the Mele Quieter 4C, a general-purpose mini PC. While competent, it lacked features tailored for astrophotography. The Gaius S2, by contrast, is a dedicated solution that closes this gap beautifully.
The Gaius S2 is a compact, lightweight mini PC, tipping the scale at just 250 grams. It's offered in several configurations ranging from an entry-level version with 4 GB RAM and 64 GB storage to a high-end version boasting 16 GB RAM and 256 GB storage. The reviewer strongly advises against the base model, considering its limitations in future-proofing and performance. The recommended configuration, with 8 GB RAM and 128 GB storage, offers the best balance of cost and capability. Internally, the system is powered by an Intel Celeron N5105 processor. While not the most powerful chip available, it outperforms the processor in the more expensive Eagle 6 and proves adequate for imaging tasks with sensors like the IMX571.
One of the defining advantages of the Gaius S2 is its power distribution system. It supports an XT30 power input and includes five 12V DC output ports that can be individually controlled. Two additional power outputs are designed with variable intensity control, ideal for dew heaters, and can be automated based on temperature and humidity readings. This eliminates the need for manual dew management, a major convenience for remote or unattended sessions. The unit also integrates four USB 2.0 and two USB 3.0 ports, ample for most rigs.
Wi-Fi performance is another area where the Gaius S2 shines. Unlike other mini PCs that often struggle to create stable hotspots, the Gaius S2 features a robust antenna capable of maintaining a connection across multiple floors, even in isolated environments. Upon booting, it automatically starts a custom Windows hotspot, letting users connect from phones, tablets, or PCs using standard remote desktop tools. This capability ensures remote operability even when no external network is present. Additionally, the device includes a microSD card slot for extended storage and a built-in display to show status indicators, such as power and hotspot activity.
Where this device really sets itself apart is in its integration with N.I.N.A., the imaging suite that the reviewer depends on for complete automation. The Gaius S2 comes preloaded with N.I.N.A., PHD2 for guiding, ASCOM drivers, and other essential utilities. The reviewer, who has personally contributed code to N.I.N.A., notes that it only took him about five minutes to have the entire rig up and running, thanks to the pre-installed software and drivers. The system's Windows environment is also optimized out-of-the-box for performance, with visual effects and background services minimized.
One of the core features of the Gaius S2 is its ASCOM-compliant switch control system. Within N.I.N.A., this allows for granular control of each power port during imaging sequences. For example, users can automatically power up the camera at the start of a session, wait for the device to stabilize, and then proceed with equipment connection, filter switching, and flat panel operations, all without manual intervention. These actions are defined in the advanced sequencer of N.I.N.A., making full automation a reality. At the session's end, the same software can be configured to shut everything down, including disconnecting devices and powering off individual components to reduce wear and save energy.
This level of control extends to smartphone use through the "Touch and Stars" interface, which requires the installation of several plugins within N.I.N.A., such as Advanced API and Three Point Polar Alignment. Once configured, this system enables full access to the Gaius S2’s functions from any device with a browser or a dedicated Android app. Users can toggle power ports, start image captures, and view results directly from their phones. The reviewer notes that this makes the Gaius S2 a serious contender to the ZWO ASIAir and even surpasses it in some areas, especially given the Windows ecosystem’s broader hardware compatibility.
Even with such a strong showing, the reviewer is candid about a few shortcomings. The LCD screen is quite bright, which might be problematic during imaging. A firmware update is expected to address this, allowing the screen to be turned off. The XT30 power input, while efficient, can be difficult to source adapters for. He had to use an XT60 to XT30 converter to integrate it smoothly into his setup. The included power cable was also short, requiring further modification. Despite these minor inconveniences, the Gaius S2’s overall utility and flexibility more than make up for them.
He contrasts the Gaius S2 with both the Eagle 6 and other DIY solutions. While it’s possible to replicate the S2’s functionality using a cheaper mini PC like the Mele Quieter 4C and an external power management device such as the Pegasus Astro Power Box, the integration and simplicity of the Gaius S2 provide a more elegant and time-saving solution. Additionally, pre-configuration, ease of setup, and Wi-Fi reliability are areas where the S2 clearly outperforms.
When comparing the S2 to other control centers like the ASIAir or StellaMate Pro, the reviewer draws clear lines between platforms. The ASIAir is known for its ease of use but remains locked into ZWO’s ecosystem. The StellaMate Pro, which uses Linux and INDI drivers, provides flexibility but has a steeper learning curve. The Gaius S2 offers the best of both worlds, broad hardware support with user-friendly operation, especially once the learning curve of N.I.N.A. is overcome.
Despite praising the S2, the reviewer acknowledges that it comes at a price. The recommended model costs €565 before tax, and the top model goes for €665. For those who only need a basic setup, this can seem steep. Still, when stacked against the Eagle 6’s €1,000+ price tag and lower specs, the Gaius S2 starts to look like a bargain. He admits it’s not cheap if you’re comparing raw specs alone, but in the context of astrophotography needs, especially integration and automation, it is more than justified.
After using the Gaius S2 extensively in Tokyo, even under challenging weather conditions, he reports successful imaging sessions that required minimal oversight. In one case, he captured three hours of clean data on the M51 galaxy using the MiniCam 8, fully automated through the Gaius S2 and N.I.N.A. From startup to shut down, every part of the process was handled through pre-set scripts, turning his rig into a near-autonomous imaging machine.
Cuiv wraps up his review with a strong endorsement of the Gaius S2, calling it a standout choice for serious astrophotographers. He’s already integrated it into his main setup and is seriously considering a second unit for his secondary rig. While he acknowledges the appeal of DIY options and other lower-cost alternatives, he believes the Gaius S2 strikes the ideal balance between smart integration, reliable automation, and practical usability.
Rather than just positioning itself as a budget version of the Eagle 6, Cuiv sees the Gaius S2 as a more thoughtful, accessible solution—one that meets the real-world needs of most astrophotographers in 2025. For those who prioritize efficiency and simplicity without sacrificing capability, it’s a compelling control hub that delivers where it counts.
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