Celestron C11-A Schmidt-Cassegrain OTA with CGE Dovetail – 91036-XLT Celestron

Celestron C11 Aluminum Optical Tube with CGE Dovetail

• 11″ Schmidt-Cassegrain Optical Tube Assembly
• Aluminum Optical Tube
• Celestron’s premium StarBright XLT coatings
• 2800 mm focal length (f/10)
• 40 mm eyepiece included (70x)
• Visual back allows for use with 1.25″ accessories
• 9×50 finderscope to help accurately find objects
• Star diagonal provides more comfortable viewing position when observing objects that are high in the sky
• Includes dovetail rail compatible with CGE mount (mount not included)

About Celestron Schmidt-Cassegrain Telescopes

Celestron’s excellent Schmidt-Cassegrain telescopes are compact and portable and represent the best all-purpose design for a wide variety of uses from terrestrial and deep sky viewing to astrophotography.

Catadioptrics use a combination of mirrors and lenses to “fold” (reflect) the light path and form an image. In a Schmidt-Cassegrain, the light enters through a thin aspheric Schmidt correcting lens. It then strikes the spherical primary mirror. It is reflected back up the tube and intercepted by a small secondary mirror which reflects the light out an opening in the rear of the instrument where the image is formed at the eyepiece.

Catadioptrics are the most popular and most modern type of telescope optical design and are marketed throughout the world in 3.5″ and larger apertures. Catadioptric telescopes combine the practical advantages of lenses and mirrors while eliminating their disadvantages. They offer the clarity and contrast of refractors with the low aberration of reflectors. Catadioptrics have an average focal ratio of f/10, which is wide enough for all types of photography. They are also easier to maintain because all optical elements are solidly mounted and rigidly collimated. Catadioptric telescopes provide the best possible combination of light gathering power, long focal length, portability and affordability.

Schmidt-Cassegrain Advantages

• Very versatile, best all-purpose telescope design
• Combines the optical advantages of both lenses and mirrors while eliminating their disadvantages
• Excellent optics and razor sharp images over a wide field
• Excellent for deep sky observing and astrophotography as well as terrestrial viewing
• Very good for lunar, planetary and binary star observing
• Focal ratio generally around f/10, it also has the best near focus capability of any type of telescope
• Closed tube design reduces image-degrading air currents
• Extremely compact and portable
• Easy to use, durable and virtually maintenance free
• Large apertures at reasonable cost and less expensive than equivalent aperture refractors
• More accessories available than with other types of telescopes

Schmidt-Cassegrain Disadvantages

• More expensive than Newtonians of equal aperture
• Slight light loss due to secondary mirror obstruction compared to refractors The Maksutov-Cassegrain is similar to the Schmidt-Cassegrain with essentially the same advantages and disadvantages. It uses a thick meniscus correcting lens with a strong curvature and a secondary mirror that is usually an aluminized spot on the corrector. The Maksutov secondary