CelestronC9-1/4A 22" long aluminum optical tube weighs only 20 lbs., making it easy to transport. CelestronC-9 1/4A has a 9.25 " aperture, a 2350mm focal length, and a focal ratio of f/10. Starbright multicoatings are standard equipment for Celestron-C 9.25" A Telescopes . These include high reflectivity 5-layer enhanced aluminum mirror coatings, plus magnesium fluoride antireflection coatings on both sides of the Schmidt corrector lens. The optics of CelestronC9-1/4A are hand-figured. Hand figuring the optical system is a complex optical procedure done on a commercial basis only by Celestron . C-9 1/4A Optical Tube comes with a 6 x 30mm straight-through achromatic finderscope and mounting bracket. Also standard C9-1/4-A equipment is a removable 1.25" visual back that holds visual accessories such as a star diagonal, tele-extender, etc. A 1.25" prism type star diagonal is also standard, as is a 1.25" 25mm Plössl eyepiece. Celestron C9 1/4 A Telescope are equipped with a dovetail slide bar for mounting on a Celestron CG5 or CG5 Computerized German equatorial mount. Optional split mounting rings are also available to put the tube on another mount of the buyer's choosing. Dust covers for the optics complete the supplied accessories. Celestron C9 1/4 A Telescopes with SarBright XLT coating : (models 91027XLT and 91025XLT)With StarBright XLT Optical System Design you'll see the light.One of the most important factors in the evaluation of a Schmidt-Cassegrain telescope 's optical system performance is its transmission - the percentage of incoming light that reaches the focal plane. The design of the XLT System accomplishes two crucial objectives: Develop a coating system that is optimized for visual use and for CCD/Photographic imaging.There are three major components that make up Celestron StarBrightXLT high transmission optical system design:1. Unique enhanced multi-layer mirror coatings:Celestron mirror coatings are made from precise layers of Al (Aluminum), SiO2 (quartz) and TiO2 (Titanium Dioxide). Reflectivity is fairly flat across the spectrum, optimizing it for both CCD imaging and visual use. 2. Multi-layer anti-reflective coatings:Coatings are made from precise layers of MgF2 (Magnesium Fluoride), and HfO2 (Hafnium Dioxide). Hafnium gives a wider band pass than Titanium, used in comparable coatings.3. High Transmission Water White glass :Celestron Schmidt-Cassegrain optical systems with optional StarBright XLT coatings use Water White glass instead of Soda Lime glass for the corrector lens. Water White glass transmits about 90.5% of light without anti-reflective coatings. That is 3.5% better transmission than uncoated Soda Lime glass. When Water White glass is used in conjunction with StarBright - XLT 's anti-reflective coatings, the average light transmission reaches 97.4% - an 8% improvement!These three components of Celestron StarBright XLT coatings result in one of the finest coatings available. The peak light transmission for the systems is 89% at 520 nm. The overall system transmission is 83.5% averaged over the spectrum from 400 to 750 nm.

Specifications for Celestron-C-9-1/4-A Telescopes:

Optical Design:		Schmidt-Cassegrain
Optical Diameter:		9.2" (203mm)
Focal Length:		92.5" (2350mm)
Focal Ratio:		f/10
Maximum Useful Magnification:		555x
Resolving Power (arc seconds):		0.59
Optical Coatings:		Starbright or StarBright-XLT coatings
Optical Tube Dimensions:		22.0" (55.9 cm) Long
Eyepiece Barrel Diameter:		1.25"
Finderscope:		9x50mm
Weight:		20.00 lb (9.07 kg)

Features of Celestron C9 1/4 A Telescopes:

• Limiting stellar magnitude of 14.4
• Focus as close as 60' (18 m) for terrestial viewing
• Secondary mirror obstruction of 13.0%(by area)
• Aluminum tube materials

Package Contents:

• Celestron C9 1/4-A Telescope
• 6x30mm Finderscope
• 25mm (94x) Plossl Eyepiece (1.25")
• Star Diagonal and Visual Back
• Dovetail Slide Bar