Celestron Telescope CGX 800 RASA, f/2.0 Review

One Week with the Celestron Telescope CGX 800 RASA, f/2.0

My quest for a capable, yet reasonably portable deep-sky imaging rig led me to the Celestron Telescope CGX 800 RASA, f/2.0. As an equipment specialist with over a decade of putting gear through its paces in diverse environments, from dusty workshops to frigid field sites, I’m always on the lookout for instruments that blend performance with practicality. The promise of the RASA design – achieving fast focal ratios that significantly cut down on exposure times – combined with Celestron’s robust CGX mount, was compelling. I needed a system that could deliver spectacular wide-field nebula and galaxy shots without the back-breaking weight and complexity of larger setups.

For years, I’d been wrestling with longer focal length telescopes, which, while capable of showing incredible detail, demanded hours of meticulous guiding and processing to yield acceptable results. The RASA 8 offered a tantalizing alternative: a way to capture more photons in less time, ideally simplifying the entire astrophotography workflow. I specifically sought out the Celestron Telescope CGX 800 RASA, f/2.0 combination because it promised to be a complete imaging solution, removing much of the guesswork in pairing a fast optical tube with a suitable mount. It felt like a significant upgrade from my previous setups, aiming to bridge the gap between dedicated astrographs and more general-purpose instruments.

Upon unboxing, the initial impression was one of solid engineering. The optical tube, while compact for its aperture, had a reassuring heft. The CGX mount, in comparison to some older Celestron mounts I’ve handled, felt noticeably more refined and substantial. It’s clear that Celestron put considerable thought into the integration of these two components. My primary considerations before purchasing included the popular Sky-Watcher Esprit 80ED Pro, known for its triplet optics, and a few other smaller aperture fast refractors. However, the f/2.0 speed of the RASA was the ultimate deciding factor, and the CGX mount seemed to be a significant step up from the standard EQ mounts often paired with smaller refractors. My first reaction was a quiet satisfaction; this felt like a serious piece of kit ready for serious work.

Real-World Testing: Putting Celestron Telescope CGX 800 RASA, f/2.0 to the Test

First Use Experience

My initial testing ground was my backyard observatory, a location typically plagued by light pollution, but also the most accessible for rapid setup and testing. The goal was to see how quickly I could get from unboxing to capturing data. Assembling the CGX mount and attaching the RASA 8 was straightforward, thanks to the clear instructions and well-designed dovetail system. I utilized the All-Star Polar Alignment procedure, which, even with imperfect sky conditions due to urban glow, proved surprisingly accurate and remarkably faster than traditional methods I’ve used in the past. Within about 30 minutes of powering up, I was slewing towards the Orion Nebula, eager to see its performance.

The RASA 8 performed admirably even under these less-than-ideal skies. Its f/2.0 aperture gathered enough light to show significant detail in M42 with relatively short exposures—mere seconds rather than minutes. This fast acquisition rate was a revelation, offering an almost real-time observing experience through live stacking software. One minor surprise was the sensitivity to focus adjustments; with such a fast system, precise focusing is paramount. The new Ultra-Stable Focus System is a noticeable improvement, minimizing image shift, but it still requires a delicate touch, especially when coupled with sensitive CMOS cameras. Despite the light pollution, the images produced were surprisingly clean, with stars remaining sharp across the field of view.

Extended Use & Reliability

Over the following weeks, I took the Celestron Telescope CGX 800 RASA, f/2.0 to a truly dark sky site, miles away from any significant light sources. This is where the true potential of the RASA design shines. The absence of coma and significant field curvature, even on my APS-C camera sensor, was evident. The deep blacks of the night sky, coupled with the incredible light-gathering capabilities of the f/2.0 optic, allowed for breathtaking captures of faint nebulae and distant galaxies. I logged several nights of continuous imaging, pushing the mount’s tracking capabilities to their limits.

In terms of durability, the system has held up exceptionally well. The CGX mount’s low cog DC servo motors and belt-and-pulley system proved to be exceptionally smooth and accurate, providing stable tracking even through meridian flips. I have experienced no binding or excessive backlash. The optical tube, despite its lightweight construction, feels robust and well-sealed. Maintenance has been minimal; a gentle wipe-down of the dew shield and occasional cleaning of the lens caps are all that’s required. I have not encountered any significant wear or tear. Compared to some older, bulkier mounts I’ve used, the CGX feels more purpose-built for imaging and significantly easier to manage logistically.

Breaking Down the Features of Celestron Telescope CGX 800 RASA, f/2.0

Specifications

The Celestron Telescope CGX 800 RASA, f/2.0 is an integrated imaging system designed for high-performance deep-sky astrophotography. Its core is the 8-inch (203mm) Rowe-Ackermann Schmidt Astrograph (RASA) optical tube, boasting a 400mm focal length and an incredibly fast f/2.0 focal ratio. This speed is achieved through a complex optical design involving a Schmidt corrector, primary mirror, and a four-element lens group utilizing rare-earth elements. The central obstruction measures 93mm (3.66″), representing about 46% of the aperture diameter.

The RASA’s optical window is designed to be removeable, allowing for the seamless integration of filters like Celestron’s own Light Pollution Imaging Filter. This thoughtful design choice ensures peak optical performance even when a filter or camera window is present in the light path. The optics are multi-coated with StarBright XLT coatings on refractive surfaces and enhanced aluminum coatings on the primary mirror, maximizing light transmission across a wide spectral range from 390-800 nm. The system is optimized for sensors with a 22mm diagonal image circle, but still performs well with larger sensors up to 32mm diagonal, making it suitable for most APS-C and smaller full-frame cameras.

The included CGX mount provides a substantial platform, with a 55 lb. load capacity, easily handling the 17 lb. RASA 8 tube, camera, and accessories. Its German equatorial design is optimized for imaging, featuring low cog DC servo motors with integrated optical encoders for precise tracking. The mount utilizes a belt-and-pulley drive system to minimize backlash, and steel worm gears supported by precision bearings. Its robust tripod features 2-inch diameter steel legs for enhanced stability. Connectivity includes a dedicated autoguider port, USB 2.0 for computer control, and two AUX ports for accessories like StarSense AutoAlign.

Performance & Functionality

The primary job of the Celestron Telescope CGX 800 RASA, f/2.0 is to capture stunning, wide-field deep-sky images with short exposure times, and it excels at this. The f/2.0 focal ratio is the star of the show, enabling the capture of faint details in nebulae and galaxies in fractions of the time required by slower systems. This translates to less time spent guiding and more time collecting data, which is invaluable for those with limited clear observing time. The flat field free of optical aberrations like field curvature, coma, astigmatism, and chromatic aberration across an APS-C sensor is not an exaggeration; star shapes are remarkably clean even at the edges of the frame.

A key strength is the synergy between the RASA’s speed and the CGX mount’s precision. The mount’s Permanent Periodic Error Correction (PPEC) and ability to track through the meridian without immediate flipping are crucial for uninterrupted imaging sessions. The Ultra-Stable Focus System is a significant functional improvement, virtually eliminating image shift. However, the extreme speed of the RASA also means that precise focusing is absolutely critical. Even minute misfocus can lead to noticeably soft stars across the entire field. This is less of a flaw and more of an inherent characteristic of ultra-fast optics. Compared to my experience with f/5 or f/6 Newtonian reflectors, the RASA demands a higher level of focus accuracy.

Design & Ergonomics

The Celestron Telescope CGX 800 RASA, f/2.0 presents a well-thought-out design for astrophotography. The optical tube itself is relatively compact and lightweight, making it manageable for single-person transport. The CGE dovetail mounting bar provides a secure connection to the CGX mount. The mount head is engineered for stability, with a design that keeps the instrument load closer to the R.A. axis, reducing torque. Ergonomic carry handles on the mount head and the tripod legs make setup and transport significantly easier.

The NexStar+ hand controller offers intuitive navigation through menus, and features like the All-Star Polar Alignment are genuinely user-friendly. The internal cabling of the CGX mount is a standout ergonomic feature, preventing snagging and tangling of wires during operation, which is crucial for both manual and remote observing. The included hex key, stored on the mount itself, is a small but appreciated touch for convenience. One minor ergonomic quibble is that while the tripod is stable, extending the 2-inch steel legs to a perfectly level position can sometimes require fine adjustments on all three legs.

Durability & Maintenance

Built for the rigors of astrophotography, the Celestron Telescope CGX 800 RASA, f/2.0 appears to be a durable and reliable system. The optical tube’s construction seems robust, and the coatings on the optics are designed for longevity. The CGX mount’s internal components, protected from the elements, should offer excellent long-term reliability. As a system purely designed for imaging, it avoids the mechanical complexities and wear points associated with visual observing adaptations.

Maintenance is refreshingly simple. The RASA tube requires careful handling and occasional cleaning of the corrector plate and lens group, similar to any sophisticated optical instrument. The CGX mount is largely maintenance-free, with sealed bearings and robust motor systems. The only potential concern I might foresee over many years of heavy use would be the eventual wear on the drive belts, though this is common to many modern equatorial mounts. Overall, this appears to be a system designed for years of dedicated service with minimal fuss, far outperforming more budget-oriented setups I’ve used previously.

Accessories and Customization Options

The Celestron Telescope CGX 800 RASA, f/2.0 kit comes with essential accessories for its primary function. This includes camera adapters for M42 threads and C-mount cameras. The included NexStar+ hand controller is the primary interface for mount control. Celestron also offers optional adapters for popular mirrorless cameras like Canon and Sony, which is a crucial consideration for those using these camera systems.

The integrated internal filter mount is a significant accessory feature, allowing for the addition of filters without impacting optical performance. For those looking to expand capabilities, the CGX mount’s autoguider port is ready for dedicated autoguiding cameras. Furthermore, the two AUX ports offer connectivity for accessories like the StarSense AutoAlign, which can further streamline the alignment process. The compatibility with third-party software via ASCOM drivers also opens up extensive customization for remote imaging control.

Pros and Cons of Celestron Telescope CGX 800 RASA, f/2.0

Who Should Buy Celestron Telescope CGX 800 RASA, f/2.0?

The Celestron Telescope CGX 800 RASA, f/2.0 is an exceptional choice for dedicated deep-sky astrophotographers who prioritize short exposure times and excellent optical quality in a relatively portable package. It’s ideal for those who have outgrown entry-level imaging setups and are looking for a significant upgrade in performance, especially for capturing nebulae and galaxies. Amateur astronomers with an APS-C or smaller sensor camera who want to maximize their imaging time and achieve stunning results with less processing effort will find this system particularly appealing.

Conversely, this telescope is not for the casual observer or someone looking for a dual-purpose visual and imaging instrument; its design is strictly for astrophotography. Those on a very tight budget might find more affordable, albeit slower, options adequate. Beginners might also find the precise focusing requirements and the learning curve of an equatorial mount system a bit steep initially, although the CGX’s features do simplify the process considerably. For those venturing into remote observing, the CGX mount’s robust design and safety features make it a solid contender. A recommended accessory would be Celestron’s optional camera adapters for mirrorless systems, and a high-quality intervalometer or dedicated astro-imaging computer for advanced control.

Conclusion on Celestron Telescope CGX 800 RASA, f/2.0

The Celestron Telescope CGX 800 RASA, f/2.0 is a top-tier imaging system that delivers on its promise of speed and optical excellence. The combination of the f/2.0 RASA optical tube with the stable and feature-rich CGX mount creates a powerful, integrated solution for deep-sky astrophotography. Its ability to capture high-quality, wide-field images with significantly reduced exposure times is a game-changer for serious imagers.

Considering its price, the Celestron Telescope CGX 800 RASA, f/2.0 represents excellent value for the performance it offers, especially when compared to assembling a similar caliber system piece by piece. It’s a system built for serious work, offering reliability, ease of use through its thoughtful design, and outstanding imaging results. I would highly recommend this telescope to any dedicated astrophotographer looking to elevate their imaging capabilities without resorting to prohibitively large or complex equipment. If your passion lies in capturing the cosmos in stunning detail and with remarkable efficiency, this RASA and CGX combination is certainly worth your serious consideration.