Sky-Watcher has stirred excitement in the astrophotography community with the release of the HAC125DX, a compact, fast f/2 astrograph that’s drawing comparisons to Celestron’s RASA series. Dubbed by some as a “mini RASA,” the HAC125DX is designed for wide-field imaging with speed and portability in mind. But does it live up to the hype?
A New Breed of Astrograph
The Sky-Watcher HAC125DX is a 125mm aperture, 250mm focal length f/2 catadioptric telescope, based on a Honders optical design—a relatively rare configuration that combines refractive and reflective elements to achieve a fast, flat field. With its rear-mounted helical focuser and compact form factor, the HAC125DX is clearly aimed at the EAA (Electronically Assisted Astronomy) and portable astrophotography markets.
Strengths: Speed and Simplicity in a Compact Package
One of the most compelling features of the Sky-Watcher HAC125DX is its blazing-fast f/2 optical speed, which allows it to gather light at a rate nearly six times faster than a typical f/5 refractor. This makes it particularly attractive for astrophotographers looking to capture deep-sky objects in shorter exposures, a major advantage for those working under time constraints or in less-than-ideal sky conditions.
The HAC125DX’s compact and lightweight design also sets it apart. With a 125mm aperture and 250mm focal length, it’s small enough to be considered a “grab-and-go” astrograph, ideal for travel or remote imaging setups. Its portability opens the door for use in mobile observatories or even integration into smart telescope systems.
Affordability is another key selling point. While pricing varies by region, early impressions suggest that the HAC125DX is significantly more accessible than other fast astrographs like the Celestron RASA or Riccardi-Honders systems. This positions it as a potential entry point for amateur astrophotographers eager to explore fast imaging without breaking the bank.
Weaknesses: Sensor Limitations and Compatibility Concerns
Despite its strengths, the HAC125DX is not without its drawbacks. Chief among them is its limited image circle, which measures just 16mm. This restricts its compatibility to smaller sensors such as the IMX533 or IMX585, effectively ruling out use with larger APS-C or full-frame cameras. For many astrophotographers who rely on these larger sensors for higher resolution and wider fields of view, this could be a dealbreaker.
While the DX version improves camera compatibility and cable management, it does not include motorized focusing out of the box, which may be a consideration for users looking to automate their imaging workflow.
Community Reception: Cautious Optimism
Across online astronomy forums like Cloudy Nights, the release of the Sky-Watcher HAC125 has sparked a lively mix of enthusiasm, curiosity, and measured skepticism. While many users are intrigued by the idea of a compact, fast f/2 astrograph at a relatively accessible price point, others are holding back, waiting for more concrete performance data before making a judgment.
Some forum members have praised Sky-Watcher for pushing innovation in a market that has long been dominated by a few key players. The HAC125’s Honders-based design and fast optics have drawn comparisons to the Celestron RASA series, but at a fraction of the cost and size. For astrophotographers using small-sensor cameras, the HAC125DX presents an exciting opportunity to capture wide-field images with short exposures and minimal gear.
However, not everyone is ready to embrace the new design. A recurring concern is the limited 16mm image circle, which restricts the scope’s use to smaller sensors like the IMX533. This has led to disappointment among users who rely on larger APS-C or full-frame sensors for their imaging work. “It’s a shame,” one user noted, “because the concept is great, but the small image circle really limits its potential.”
Others have expressed caution about the lack of real-world imaging results. While the theoretical performance of the HAC125DX is promising, many in the community are waiting for early adopters to share first-light images and long-term usage reports. As one user succinctly put it, “It’s good to have more options, but I’ll wait for real-world results before jumping in.”
Despite the mixed reactions, the overall tone remains one of cautious optimism. The HAC125DX may not be a universal solution, but it represents a bold step forward in making fast, wide-field imaging more accessible. As more users get their hands on the scope and begin sharing results, the community’s verdict will become clearer.
Final Word
The Sky-Watcher HAC125DX is not a one-size-fits-all solution, but it fills a unique niche. For astrophotographers using small-sensor cameras who value speed and portability, it could be a game-changer. However, those seeking full-frame compatibility or high-end performance may find its limitations too restrictive.