CelestronC9-1/4CF is 9.25"/235mm Aluminum Schmidt-Cassegrain Telescope Optical Tube Assembly
CelestronC9-1/4C-F Telescope 91026-XLT is the same as #91027 (Celestron C9 1/4 A Telescope) except uses a carbon fiber optical tube.
CelestronC9-1/4 CF 22" long aluminum optical tube weighs only 20 lbs., making it easy to transport. CelestronC-9 1/4CF 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" CF 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 CelestronC9-1/4CF are hand-figured. Hand figuring the
optical system is a complex optical procedure done on a commercial basis only by
C-9 1/4CF Optical Tube comes with a 6 x 30mm straight-through achromatic finderscope and mounting bracket. Also standard C9-1/4-CF 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.
CelestronC-9 1/4 CF Telescopes 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.
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