Celestron C9.25 Optical Tube Assembly (CGE Dovetail)

Celestron C9.25 Optical Tube Assembly (CGE Dovetail)

The Celestron C9.25 stands out with its distinctive 9.25” aperture and 2350 mm focal length, a combination many astronomers regard as the “Goldilocks” size–neither too small nor too large. Constructed from durable aluminum, the optical tube measures just 22 inches in length and weighs only 20 pounds, making setup and transport surprisingly easy. Despite its compact build, it delivers breathtaking views with a focal ratio of f/10, along with the added flexibility of Fastar compatibility.

This optical tube is enhanced with Celestron’s exclusive StarBright® XLT optical coatings, which significantly boost light transmission and image contrast. The result is brighter, sharper deep-sky images and shorter exposure times for astrophotography. With the C9.25, you can detect delicate details while observing the Moon, planets, galaxies, and nebulae.

Thanks to its CGEM-style dovetail bar, the Celestron C9.25 can be mounted on a wide range of computerized telescope mounts. This versatile and iconic OTA strikes the ideal balance between portability, ease of use, light-gathering capability, and price–making it a favorite among amateur astronomers.

Fastar Technology

Back in 1997, when CCD cameras were beginning to revolutionize astrophotography, Celestron collaborated with the Santa Barbara Instruments Group (SBIG) to introduce Fastar, a breakthrough upgrade to the Schmidt-Cassegrain design.

With Fastar, the telescope’s secondary mirror can be removed and replaced with a field-flattener lens assembly (sold separately by third-party manufacturers), allowing a CCD camera to be mounted at the front of the scope at the f/2 focal ratio of the primary mirror. This innovation made exposure times up to 25× faster compared to imaging at the native f/10 focus. Imagers can capture galaxies and nebulae in as little as 30 seconds.

StarBright XLT Coatings

Celestron’s StarBright XLT coating system is one of the most advanced in the telescope industry, outperforming competing systems with its superior light throughput. It consists of three key components:

   ➜  Enhanced multi-layer mirror coatings, using precision layers of aluminum, quartz (SiO₂), titanium dioxide (TiO₂), and additional quartz for consistent reflectivity across the spectrum–optimized for both visual and photographic use.

   ➜  Multi-layer anti-reflective coatings, made with magnesium fluoride (MgF₂) and hafnium dioxide (HfO₂). Hafnium, a rare and costly element, provides a wider bandpass than coatings based on titanium.

   ➜  High-transmission water-white glass corrector lens, which allows ~90.5% light transmission before coatings–3.5% higher than standard soda-lime glass. Combined with the XLT system, the average transmission reaches an impressive 97.4%, ensuring maximum image brightness and clarity.