Celestron C6-A-XLT Optical Tube Assembly OTA Telescope w/ StarBright XLT Coatings for CG-5 Mount. 0"/150mm Aluminum Schmidt-Cassegrain Telescope Optical Tube Assembly. The Celestron C6-A XLT OTA Telescope has a 16" long aluminum optical tube that weighs only 10 lbs. making it easy to transport. CelestronC6A Telescope features a 6" aperture a 1500 mm focal length and a focal ratio of f/10. StarBright XLT coatings are standard for Celestron C6-A. These include high reflectivity 5-layer enhanced aluminum mirror coatings plus magnesium fluoride antireflection coatings on both sides of the Schmidt corrector lens. These telescopes feature multicoatings that visibly increase contrast on subtle lunar planetary and nebula details when compared with a scope with standard coatings. They also give you higher light transmission for brighter deep space images and shorter exposure times during photography. The C-6A 's optics are hand-figured. Hand figuring the optical system is a complex optical procedure done on a commercial basis only by Celestron. Celestron C-6-A Telescopes come with a 6 x 30mm straight-through achromatic finderscope and mounting bracket. Also standard equipment for Celestron Telescopes 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 Pl ssl eyepiece. C6-A Telescopes are equipped with a dovetail slide bar for mounting on a Celestron CG 5 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 for this OTA Telescopes. 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. Specifications for Celestron C6A XLT Optical Tube Assembly OTA Telescope w/ StarBright XLT Coatings 91010 XLT: OPTICAL DESIGN: Schmidt-Cassegrain APERTURE: 150 mm (5.91 in) FOCAL LENGTH: 1500 mm (59.06 in) FOCAL RATIO: 10 EYEPIECE 1: 25 mm (0.98 in) MAGNIFICATION 1: 60 x FINDERSCOPE: 6x30 STAR DIAGONAL: 1.25 OPTICAL TUBE: Aluminum - black FASTAR COMPATIBLE: No HIGHEST USEFUL MAGNIFICATION: 354 x LOWEST USEFUL MAGNIFICATION: 21 x LIMITING STELLAR MAGNITUDE: 13.4 RESOLUTION (RAYLEIGH): 0.93 arcsec RESOLUTION (DAWES): 0.77 arcsec LIGHT GATHERING POWER: 459 x ANGULAR FIELD OF VIEW: .83 LINEAR FIELD OF VIEW (at1000 YDS): 44 ft (13.41 m) SECONDARY MIRROR OBSTRUCTION: 2.2 in (55.88 mm) SECONDARY MIRROR OBSTRUCTION BY DIAMETER: 37.3 percent SECONDARY MIRROR OBSTRUCTION BY AREA: 13.9 percent OPTICAL COATINGS: StarBright XLT OPTICAL TUBE LENGTH: 16 in (406.4 mm) OPTICAL TUBE WEIGHT: 10 lb (4.54 kg) DOVETAIL COMPATIBILITY: CG-5 Mount Features of Celestron C6-A XLT Optical Tube Assembly OTA Telescope w/ StarBright XLT Coatings 91010XLT: 6in Schmidt-Cassegrain Optical Tube Assembly Aluminum Optical Tube Celestron's premium StarBright XLT coatings 1500 mm focal length (f/10) 25 mm eyepiece included (60x) Visual back allows for use with 1.25" accessories 6x30 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 CG-5 Advanced Series mount Package Contents: Celestron C6-A-XLT 6" Schmidt-Cassegrain Optical Tube Assembly 91010-XLT 25 mm eyepiece (60x) 6x30 finderscope Star diagonal Dovetail rail for CG-5