The Celestron C8-A Optical Tube Assembly (OTA) can be seen as an enhanced version of Celestron's pioneering C8 model, which significantly influenced amateur astronomy when it was introduced in 1970. Despite its portable design — weighing in at only 13 pounds and measuring 17 inches long — this aluminum tube offers surprisingly powerful views. It has a focal length of 2032 mm and an f/10 focal ratio. Additionally, it features the option for Fastar technology (more on that below).

Coated with Celestron's proprietary StarBright® XLT optical coatings, the tube excels in increasing contrast and light transmission. This means you'll capture vibrant and highly detailed images of celestial objects like the Moon, planets, and even elusive galaxies and nebulae.

Mounting the C8-A is a breeze, thanks to its CGEM-style dovetail bar, making it compatible with a wide range of computerized telescope mounts. Overall, this OTA offers an unbeatable combination of portability, ease of use, light-gathering capacity, and affordability for amateur astronomers.

Fastar Technology Explained

In 1997, when CCD cameras were revolutionizing astrophotography, Celestron collaborated with the Santa Barbara Instruments Group (SBIG) to introduce Fastar. This add-on to Celestron's Schmidt-Cassegrain Telescopes (SCTs) transforms your optical system by allowing the removal of the secondary mirror. It can be replaced with a field-flattening lens assembly (available separately from third-party manufacturers), permitting a CCD camera to operate at the f/2 focus of the primary mirror. The result is a drastic reduction in exposure time — up to 25 times shorter than using the native f/10 focus. This allows for quick 30-second captures of galaxies and nebulae.

The Scoop on StarBright XLT Coatings

StarBright XLT sets a high bar in the telescope industry, outclassing other available coatings. It comprises three main elements:

Multi-layer Mirror Coatings: Composed of precision-layered aluminum, SiO2 (quartz), TiO2 (titanium dioxide), and SiO2 (silicon dioxide), these coatings offer uniform reflectivity across the light spectrum, perfect for both imaging and visual observation.
Anti-Reflective Coatings: Made from layers of MgF2 (magnesium fluoride) and HfO2 (hafnium dioxide), this element offers a broader band pass, thanks to hafnium—a rare and expensive material.
Water White Glass: For the corrector lens, high-transmission water white glass is used, which lets through about 90.5% of light without any coatings. That's an improvement of 3.5% over traditional uncoated soda lime glass. Paired with StarBright XLT coatings, the average light transmission astonishingly reaches 97.4%.

For more information on StarBright XLT, you can visit Celestron's dedicated web page.

Specifications

Optical Design:	Schmidt-Cassegrain
Aperture:	203.2mm (8")
Focal Length:	2032mm (80")
Focal Ratio:	f/10
Focal Length of Eyepiece 1:	25mm (0.98")
Magnification of Eyepiece 1:	81x
Finderscope:	6x30
Star Diagonal:	1.25" Star Diagonal
Optical Tube:	Aluminum
Highest Useful Magnification:	480x
Lowest Useful Magnification:	29x
Limiting Stellar Magnitude:	14
Resolution (Rayleigh):	0.69 arc seconds
Resolution (Dawes):	0.57 arc seconds
Light Gathering Power (Compared to human eye):	843x
Secondary Mirror Obstruction:	64mm (2.5")
Secondary Mirror Obstruction by Diameter:	31%
Secondary Mirror Obstruction by Area:	9.77%
Optical Coatings:	StarBright XLT
Optical Tube Length:	432mm (17")
Optical Tube Diameter:	238mm (9.37")
Optical Tube Weight:	12.5 lbs (5.67 kg)
Dovetail:	CGE Dovetail Bar
Solar Warning	Never look directly at the Sun with the naked eye or with an optic (unless you have the proper solar filter). Permanent and irreversible eye damage may result. Never use your optic to project an image of the Sun onto any surface. Internal heat build-up can damage the optic and any accessories attached to it. Never leave your optic unsupervised. Make sure an adult who is familiar with the correct operating procedures is with your optic at all times, especially when children are present.
California Residents	View Proposition 65 Warning

Software and Documentation

8" Schmidt-Cassegrain Optical Tube Assembly Dimensional Drawing

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Celestron C8 SCT OTA - CGE

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